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Prevalence and correlates of alcohol and tobacco use among key populations in Togo in 2017: a cross-sectional study

Objectives The aim of this study was to estimate alcohol and tobacco use prevalence and their correlates among female sex workers (FSW), men who have sex with men (MSM) and drug users (DU) in Togo. Design, setting and participants A cross-sectional bio-behavioural study was conducted among 2115 MSM, FSW and DU in 2017 using a respondent-driven sampling method, in the eight biggest towns of Togo. Selection criteria for the MSM were being male and having had oral or anal intercourse with a man in the previous 12 months; for FSW, being a female and having exchanged sex for money in the previous 12 months; and for DU, consuming heroin, cocaine or hashish for MSM, FSW and DU, respectively. All participants had to be at least 18 years old and residing in the territory for the past 3 months. Results The prevalence of alcohol consumption, hazardous/harmful consumption and binge drinking was 64.8%, 38.4% and 45.5%, respectively. Current tobacco use was reported by 30.6% of participants and HIV prevalence was estimated at 12.5%. DU were more likely to engage in binge drinking compared with other key populations (adjusted odds ratio (aOR)=2.0; 95% CI 1.4 to 2.8; p=0.001). Participants who were identified as having hazardous/harmful alcohol consumption had almost three times the odds of tobacco consumption than those with no risky consumption (aOR=2.6; 95% CI 2.0 to 3.4; p=0.001). Hazardous/harmful alcohol consumption was three times more likely among participants with severe psychological distress compared with those with no psychological distress (aOR=3.3, 95% CI 2.2 to 5.1; p=0.001). Conclusion Findings from this study demonstrate the need for the integration of mental health and substance abuse reduction interventions into HIV prevention programme, particularly those geared towards key populations.

. In West and Central Africa, the HIV epidemic is described as generalized and driven by heterosexual sex with an estimated prevalence of 2.2% (2).
However, in key populations, populations at higher risk of HIV such as sex workers, men who have sex with men (MSM) and injection drug users, the reported prevalence rates are disproportionally high compared to those of the general population (3,4). In Togo, HIV prevalence among key populations ranges from 11% to 13% compared to 2.1% in the general population (5). Several biological, behavioral and structural risk factors are associated with this high HIV rate among key populations: unprotected sex, presence of other Sexually Transmitted Infections (STIs), lack of access to condoms, multiple concurrent sex partners (males and females for MSM), lack of access to health care and prevention services, physical and sexual violence, challenging legal and sociopolitical environment, poverty, sociopolitical stigma and discrimination (3,4).
Other risk factors associated with sexual risk behaviors and thus contributing to HIV transmission include alcohol and tobacco consumption. Alcohol, a psychoactive substance with dependenceproducing properties, has been an integral part of many cultures for several centuries (6). The harmful use of alcohol and its consequences make its consumption a public health problem. More than 200 disease and injury conditions including alcohol dependence, liver cirrhosis, cancers and injuries are the consequences of the harmful use of alcohol (6). In 2012, it was reported that 5.9% of all global deaths and 5.1% of the global burden of disease and injury were the consequences of harmful alcohol consumption (6). Recent research studies have also uncovered a causal relationship between the harmful use of alcohol and infectious diseases, including HIV (6)(7)(8). This relation could be attributed to the fact that alcohol influences cognitive abilities and decision making, and affects condom negotiation and correct condom use (9). Among key populations, particularly sex workers, alcohol consumption is seen as a sexual enhancer and work requirement which in many cases leads to an increased likelihood of unprotected sex, economic loss, interference with family responsibilities and sexual violence (8,10,11).
Tobacco consumption is also one of the biggest public health challenges of the 21 st century, with a clear, causal link between tobacco use and health. It is estimated that tobacco use kills half of its users and is responsible for the death of more than 7 million people a year. Approximately 80% of tobacco users live in low and middle income countries (12). Tobacco use is one the main risk factors for lung cancer, disability and death from non-communicable chronic diseases, and also an increased risk of death from communicable diseases (13,14). For people living with HIV, tobacco use is a risk factor for HIV-related comorbidities and premature death (15). Estimates in Togo put the prevalence of alcohol and tobacco consumption at 53.7% and 8.5% respectively, in the general population (16).

Patient and Public Involvement
Members of key populations were involved during the study design and data collection phases of the study. They were consulted prior to the study for their input on the best method to reach out to key populations and they were actively involved in the recruitment process.

Socio-demographic characteristics
A total of 641 MSM, 537 DU and 937 FSW, with a median age of 25 years, interquartile range (IQR) [21-32 years] participated in the study. The majority of the sample (n=1,443; 54.0%) had a secondary school education level and 76.7% were Christians (n=1,621). Approximately two-thirds of the sample (n=1,278; 60.4%) were likely to not have any psychological distress and 6.5% (n=136) were identified as having severe psychological distress, the highest among female-DU (n=9; 33.4%). The HIV prevalence was 12.5% across the three populations, with the highest prevalence among MSM (20.4%).
Other socio-demographic characteristics are summarized in Table 1.

Alcohol and tobacco consumption
Alcohol and tobacco consumption patterns are presented in Table 2. Overall, the prevalence of alcohol consumption among the three groups was 64.8%. Most participants were identified as having a hazardous/harmful alcohol consumption (n=813; 38.4%), with the highest proportion among DU (74.1% among female-DU and 61.7% among male-DU; 36.7% among FSW; and 20.9% among MSM; p <0.001). More than a quarter of FSW (n=275; 29.4%) were moderate drinkers. The MSM subgroup had the highest proportion of non-drinkers (n=338; 52.7%), followed by FSW (n=318; 33.9%). The overall prevalence of binge drinking was 45.5% (n=962) and was the highest among DU: 80.0 % among female-DU (n=20) and 80.2% among male-DU (n=340) ( Table 2).
The prevalence of tobacco consumption was 30.6% among the three groups. DU had the highest proportion of smokers with 85.2% of female-DU (n=23) and 80.6% of male-DU (n=411). The highest proportion of non-smokers were FSW (n=821; 87.6%), followed by MSM (n=544, 84.9%). Of the people who smoked, 63.1% were smoking every day, including 79.1% of DU (female-DU: n=16; 69.6%, male-DU: n=327; 79.6%), 42.2% of FSW and 16.5% of MSM. Table 3 summarizes the association between the independent variables and the hazardous/harmful consumption of alcohol and binge drinking. The odds of hazardous/harmful alcohol consumption were

Tobacco use risk factors
Living in cities other than Lomé (the capital city) (aOR=0.6; 95%CI 0.5-0.8), hazardous/harmful alcohol consumption (aOR=2.6; 95% CI 2.0-3.4), having mild (aOR=1.5; 95% CI 1.1-2.1) or moderate (aOR=2.0; 95% CI 1.3-2.8) psychological distress, being a FSW (aOR=0.6; 95% 0.4-0.9), a female-DU (aOR=17.2; 95% CI 5.9-62.8) or a male-DU (aOR=18.2; 95%CI: 12.4-26.6) were associated with tobacco use (  The aim of this study was to assess the prevalence of hazardous/harmful, binge alcohol consumption as well as tobacco consumption, and explore correlates of heavy alcohol consumption and tobacco use in three key populations in Togo. We observed a high prevalence of hazardous/harmful alcohol consumption and binge drinking. Alcohol consumption is frequent among FSW and much more among DU, specifically female-DU. In addition, there was a dose-response effect relationship between alcohol consumption and psychological distress across all three populations. Tobacco use was highly prevalent among DU and among people who had a hazardous/harmful alcohol consumption. Alcohol consumption is highly prevalent among key populations groups: more than half of the sample were categorized as moderate or hazardous drinkers. This has been corroborated in the literature among key population groups. In a recent study in Kenya, among 1,476 MSM, 44% of the sample had a hazardous alcohol consumption, and, no relationship was found between alcohol and tobacco consumption and HIV infection (25). In another study among 3,588 MSM in China, alcohol prevalence was 56.1% with 16.8% of them being binge drinkers and 14.4% being recent hazardous drinkers, using the WHO AUDIT-C scale (26). Recent alcohol misuse was associated with increased sexual and HIV/syphilis risks as well as sexual risk behaviors including alcohol use before sex, sex without condoms and multiple concurrent partnerships. A prospective cohort study among 1,027 FSW in Uganda found that 78% of the sample reported using alcohol with 71% admitting to using alcohol at least once a week, with a reduced prevalence of 54% after two years of intervention (27). This emphasizes the need for alcohol risk reduction programs and programs specifically focused on the adoption of safer drinking practices integrated into HIV prevention packages and geared towards highly exposed groups (26,27).
Alcohol and tobacco consumption are particularly relevant to people living with HIV (PLHIV). Studies have demonstrated a negative impact of alcohol, tobacco and drug use on life expectancy for HIVpositive patients (28). Alcohol and tobacco use have also been associated with poor adherence to antiretroviral therapy (ART) and the interaction between all those substances leading to a higher susceptibility to co-morbidities, opportunistic infections such as tuberculosis (TB) (29,30). In this study, hazardous/harmful alcohol consumption and binge drinking were both significantly associated with tobacco use. This indicates the need for targeted prevention actions such as smoking cessation treatment and alcohol reducing counseling, among key populations, particularly among key populations living with HIV. A systematic review of interventions to reduce alcohol use among MSM indicated that although interventions such as motivational interviewing (MI) appear to be effective among MSM, they are scarce (31).
Psychological distress was found to have a dose-response relationship with alcohol consumption. Severe psychological distress was at least twice higher among people with a hazardous/harmful alcohol F o r p e e r r e v i e w o n l y 11 consumption and people who were binge drinking. This is consistent with other studies that found a relationship between alcohol and drug abuse and psychological symptoms such as depression, anxiety and suicidal ideation among key populations (32,33) . Consistent with our findings, a study conducted in Cambodia among MSM found that 38.8% had severe psychological distress and that severe psychological distress was associated with alcohol and drug use, poor self-reported quality of life and reduced condom use at last sex (32). Another study among PLHIV in Uganda found that psychological distress was significantly associated with non-adherence to ART (34). This has implication for HIV prevention and further demonstrates the need for integrated services of mental health interventions, psychological support as well as substance abuse reduction program into HIV prevention programs. This would also imply that health care workers be sufficiently armed through training to screen and refer KP in need of those interventions.
Very few studies have explored alcohol and tobacco consumption patterns among the three main key populations. This study found quite different patterns of consumption among the three groups, with MSM in this sample being the lowest at-risk group for hazardous/harmful alcohol consumption, binge drinking and tobacco use. DU on the other hand, particularly female-DU appear to be most vulnerable to hazardous/harmful alcohol consumption, binge drinking and tobacco use, as well as the group with the highest prevalence of severe psychological distress. This could potentially indicate that there is a difference in coping strategies for key populations and that, behavioral interventions specifically geared towards MSM have elements that perhaps have successfully enhanced their capacity to cope with the stress among the most marginalized groups. For example, studies have demonstrated the effectiveness of community-based organizations (CBOs), peer-led interventions and community engagement in HIV prevention among MSM (35)(36)(37). With the feminization of the HIV epidemic in SSA, it would be essential that female-DU be particularly taken into account as one of the most vulnerable and at risk group for HIV and that, targeted interventions be geared toward generating an interest for community building.
Strengths of this study include the large sample size of the three main types of key populations. In addition, to our knowledge, this is the first study in Togo comparing alcohol and tobacco consumption in these key populations using standardized tools (AUDIT, Tobacco Questions for Surveys, and Kessler psychological distress scale). Finally, this study was completed in eight main cities of Togo, which could indicate that it is nationally representative.
However, there were few limitations including the fact that some variables such as childhood abuse, stigma, or recent trauma which could influence alcohol and tobacco consumption, have not been collected. Furthermore, self-reported data used in this study, are prone to social desirability and recall bias. Despite these limitations, the results presented in this study make a unique contribution to the literature on hazardous/harmful and binge alcohol consumption among key populations in West Africa. Alcohol and tobacco use and abuse are highly prevalent among key populations. There is a need for mental health and substance abuse screening, referral and treatment fully integrated into HIV prevention services for key populations.  1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36  37  38  39  40  41  42  43  44  45  46  47  48  49  50  51  52  53  54  55  56  57  58  59  ABA and FGK contributed equally to this paper. ABA, FGK, PAC and DKE conceived and designed the study with inputs from AJ. PJ, EKS, CAD, MS and TJB facilitated data collection and contributed to analysis of the data. ABA and FGK analyzed, interpreted the data and drafted the manuscript. PAC, AJ and DKE revised the manuscript for important intellectual content. All authors participated in the revision process and have approved the final version of the manuscript.

Objectives
The aim of this study was to estimate alcohol and tobacco use prevalence and their correlates among female sex workers (FSW), males who have sex with males (MSM) and drug users (DU) in Togo.

Design, setting and participants
A cross-sectional bio-behavioral study was conducted among 2,115 MSM, FSW and DU in 2017 using a respondent-driven sampling (RDS) method, in the eight biggest towns of Togo. Selection criteria for the MSM were being male and having had oral or anal intercourse with a man in the previous 12 months; for FSW, being a female and having exchanged sex for money in the previous 12 months; and for DU, consuming heroin, cocaine or hashish for MSM, FSW and DU, respectively. All participants had be to at least 18 years old and residing in the territory for the past three months.

Results
The

Conclusion
Findings from this study demonstrate the need for the integration of mental health and substance abuse reduction interventions into HIV prevention programs, particularly those geared toward key populations.

Strengths and limitations of this study
 This study is among the first in sub-Saharan Africa exploring the patterns of alcohol and tobacco consumption among the three main groups of key populations  This study had a consistent sample size  The use of internationally validated instruments to assess alcohol and tobacco consumption, as well as psychological distress minimized bias  The main limitation of our study is that it was based on self-reported data which could be a potential source of recall bias or social desirability bias  (1). In West and Central Africa, the HIV epidemic is described as generalized and driven by heterosexual sex with an estimated prevalence of 2.2% (1).
However, in key populations, populations at higher risk of HIV such as sex workers, men who have sex with men (MSM) and injection drug users, the reported prevalence rates are disproportionally high compared to those of the general population (2,3). In Togo, HIV prevalence among key populations ranges from 11% to 13% compared to 2.1% in the general population (4). Several biological, behavioral and structural risk factors are associated with this high HIV rate among key populations: unprotected sex, presence of other Sexually Transmitted Infections (STIs), lack of access to condoms, multiple concurrent sex partners (males and females for MSM), lack of access to health care and prevention services, physical and sexual violence, challenging legal and sociopolitical environment, poverty, sociopolitical stigma and discrimination (2,3).
Other risk factors associated with sexual risk behaviors and thus contributing to HIV transmission include alcohol and tobacco consumption. Alcohol, a psychoactive substance with dependenceproducing properties, has been an integral part of many cultures for several centuries (5). The harmful use of alcohol and its consequences make its consumption a public health problem. More than 200 disease and injury conditions including alcohol dependence, liver cirrhosis, cancers and injuries are the consequences of the harmful use of alcohol (5). In 2012, it was reported that 5.9% of all global deaths and 5.1% of the global burden of disease and injury were the consequences of harmful alcohol consumption (5). Recent research studies have also uncovered a causal relationship between the harmful use of alcohol and infectious diseases, including HIV (5)(6)(7). This relation could be attributed to the fact that alcohol influences cognitive abilities and decision making, and affects condom negotiation and correct condom use (8). Among key populations, particularly sex workers, alcohol consumption is seen as a sexual enhancer and work requirement which in many cases leads to an increased likelihood of unprotected sex, economic loss, interference with family responsibilities and sexual violence (7,9,10).
Tobacco consumption is also one of the biggest public health challenges of the 21 st century, with a clear, causal link between tobacco use and health. It is estimated that tobacco use kills half of its users and is responsible for the death of more than 7 million people a year. Approximately 80% of tobacco users live in low and middle income countries (11). Tobacco use is one the main risk factors for lung cancer, disability and death from non-communicable chronic diseases, and also an increased risk of death from communicable diseases (12,13). For people living with HIV, tobacco use is a risk factor for HIV-related comorbidities and premature death (14). Estimates in Togo put the prevalence of alcohol and tobacco consumption at 53.7% and 8.5% respectively, in the general population (15).

Study design, sampling and recruitment
This study was a bio-behavioral cross-sectional study conducted from August to September 2017 in Togo. Togo is a country of West Africa, with a population of 7.6 million inhabitants in 2018, covering 57,000 square kilometres with an average density of 133 inhabitants per square kilometres, an infant mortality of 45.2/ 1,000 and an estimated life expectancy of 64.5 years old. The HIV prevalence in Togo is estimated at 2.1%, with a high prevalence among key population groups (4). Togo is divided into five regions and in each region, based on the mapping and size estimation studies previously carried out in Togo (16), towns with the highest number of key populations were selected: Dapaong in the Savanes region; Kara in Kara region; Sokodé in the Centrale region; Atakpamé and Kpalimé in the Plateaux region and Tsévié, Aného and Lomé, the capital city in the Maritime region. Prior to the study, locations (associations and hot spots) specific to each group of key population were identified during preliminary visits with the help of leaders from these communities. DU and FSW were recruited in drugdealing/consumption locations and brothels (licensed or not), respectively. MSM were recruited using a Respondent Driven Sampling (RDS) method (17,18). MSM community leaders were the first "seeds".
A total of 28 seeds were identified at first based on their roles in their community and on their representativeness. Each seed from the first wave selected had to represent at least one MSM sub-group, based on how MSM self-identify as bisexuals or gays (19,20). Each participant was then given three coupons with a unique identification code to recruit three other seeds in their network until the required sample size for each group was reached. Inclusion criteria for the three groups were being 18 years or older, living/working/studying in Togo for a minimum of 3 months at the time of the study, and being in possession of a recruitment coupon. In addition to these criteria, criteria specific to MSM were having had anal and/or oral sex with a man in the previous 12 months, for FSW having had sex in exchange for money as a compensation in the previous 12 months and for DU, consuming heroin, cocaine or hashish at the time of the study.

Sample size estimation
The sample size estimation was based on the estimated prevalence of hazardous alcohol drinking among key populations of 9.1% (21). We also took into account the prevalence of tobacco use, with the assumption that tobacco use prevalence in the key populations would be twice that of the general population. Hence, with a tobacco use prevalence of 6.8% in the general population, the expected prevalence of tobacco use among key populations was 13.6% (15). With a precision of 3% and an assumption of 10% of missing data, the minimum sample size was estimated at 552 participants per group at a minimum. Thus, to allow a comparison between groups, the total sample size estimated for the three groups of key populations was 1,656.

Study procedures
After eligibility screening and written informed consent approval, trained study staff administered a structured and standardized questionnaire during a face-to-face interview. The questionnaire was constructed based on validated tools such as the Alcohol Use Disorders Identification Test (AUDIT) (22) and a subset of the Tobacco Questions for Surveys (23) to assess alcohol and tobacco consumption respectively. The Kessler Psychological Distress Scale (K10) (24) was used to measure psychological distress and the Family Health International (FHI) 360 validated guide for bio-behavioral surveys (25) was adapted to collect information on socio-demographic characteristics, risky sexual behaviors, STIs, HIV prevention methods, HIV testing history, access to health care services, and HIV knowledge. The questionnaires were used across the three populations with slight adaptations depending on the population.

Scores and operational definitions
The AUDIT was used to assess alcohol consumption. The AUDIT is a set of 10-item standardized screening instrument measuring self-reported alcohol use in the past 12 months, alcohol dependence symptoms, and alcohol-related problems to screen for excessive drinking. Each question of the AUDIT can obtain a score from zero (0) to four (4). A score ≥8 for men and ≥7 for women indicates hazardous/harmful drinking, while a score of 0 indicates a non-drinker; moderate alcohol use lies inbetween (22,26,27). Binge drinking or heavy episodic drinking was defined as the consumption of six or more alcohol drinks on at least one occasion in the past 30 days (third item of the AUDIT) (22).
Tobacco use was assessed using six questions indicating participants' smoking habits, frequency of smoking, history of smoking, type of products smoked and attempts at stopping to smoke (23).
The Kessler Psychological Distress Scale (K10) was used to measure psychological distress. This scale has been examined and validated among several populations and aims at measuring anxiety and depression with a 10-item questionnaire, each question pertaining to an emotional state and a five-level response scale for each response. The score obtained from the scale allows to categorize participants into four categories of psychological distress: severe (score ≥ 30), moderate (score: 25-29), mild (score: [20][21][22][23][24] and none (score < 20) (28).

Statistical analysis
Descriptive statistics were performed and results were presented with frequency tabulations and percentages. Prevalences were estimated with their 95% confidence interval (95%CI). Univariate and multivariate logistic regression were performed to identify factors associated with: i) hazardous/harmful alcohol consumption, ii) binge drinking and iii) current tobacco consumption. For model building, characteristics that had a p-value <0.20 in univariate analysis were considered for the full multivariable models, which were then finalized using a stepwise, backward elimination approach. The three models did not include the variable "sex" as the four groups were already categorized according to sex. All analyses were performed using R® software.

Ethical consideration
This study was approved by the "Comité de Bioéthique pour la Recherche en Santé (CBRS)" (Bioethics Committee for Health Research) from the Togo Ministry of Health. Participants provided written consent prior to participation. Potential participants were told about the study purpose and procedures, potential risks and protections, and compensation. Informed consent was documented with signed consent forms.

Patient and Public Involvement
Members of key populations were involved during the study design and data collection phases of the study. They were consulted prior to the study for their input on the best method to reach out to key populations and they were actively involved in the recruitment process.

Socio-demographic characteristics
A total of 641 MSM, 537 DU and 937 FSW, with a median age of 25 years, interquartile range (IQR) [21-32 years] participated in the study. The majority of the sample (n=1,443; 54.0%) had a secondary school education level and 76.7% were Christians (n=1,621). Approximately two-thirds of the sample (n=1,278; 60.4%) were likely to not have any psychological distress and 6.4% (n=136) were identified as having severe psychological distress, the highest among DU (n=68; 12.7 %). The HIV prevalence was 12.5% across the three populations, with the highest prevalence among MSM (20.4%). Study participants were informed of their blood test results by trained health professionals from HIV clinics.
Newly diagnosed HIV positive patients were referred to an HIV clinic for HIV treatment and care.
Socio-demographic and health characteristics are summarized in Table 1.

Alcohol and tobacco consumption
Alcohol and tobacco consumption patterns are presented in Table 2. Overall, the prevalence of alcohol consumption among the three groups was 64.8%. Most participants were identified as having a hazardous/harmful alcohol consumption (n=813; 38.4%), with the highest proportion among DU (62.4% among DU; 36.7% among FSW; and 20.9% among MSM; p <0.001). More than a quarter of FSW (n=275; 29.4%) were moderate drinkers. The MSM subgroup had the highest proportion of non-drinkers (n=338; 52.7%), followed by FSW (n=318; 33.9%). The overall prevalence of binge drinking was 45.5% and was the highest among DU (67.0%) ( Table 2).

Discussion
The aim of this study was to assess the prevalence of hazardous/harmful, binge alcohol consumption as well as tobacco consumption, and explore correlates of heavy alcohol consumption and tobacco use in three key populations in Togo. We observed a high prevalence of hazardous/harmful alcohol consumption and binge drinking. Alcohol consumption was frequent among FSW and much more among DU. In addition, there was a dose-response effect relationship between alcohol consumption and psychological distress across all three populations. Tobacco use was highly prevalent among DU and among people who had a hazardous/harmful alcohol consumption.
Alcohol consumption is highly prevalent among key populations groups: more than half of the sample were categorized as moderate or hazardous drinkers. This has been corroborated in the literature among key population groups. In a recent study in Kenya, among 1,476 MSM, 44% of the sample had a hazardous alcohol consumption, and, no relationship was found between alcohol and tobacco consumption and HIV infection (29). In another study among 3,588 MSM in China, alcohol prevalence was 56.1% with 16.8% of them being binge drinkers and 14.4% being recent hazardous drinkers, using the WHO AUDIT-C scale (30). Recent alcohol misuse was associated with increased sexual and HIV/syphilis risks as well as sexual risk behaviors including alcohol use before sex, sex without condoms and multiple concurrent partnerships. A prospective cohort study among 1,027 FSW in Uganda found that 78% of the sample reported using alcohol with 71% admitting to using alcohol at least once a week, with a reduced prevalence of 54% after two years of intervention (31). This emphasizes the need for alcohol risk reduction programs and programs specifically focused on the adoption of safer drinking practices integrated into HIV prevention packages and geared towards highly exposed groups (30,31).
Alcohol and tobacco consumption are particularly relevant to people living with HIV (PLHIV). Studies have demonstrated a negative impact of alcohol, tobacco and drug use on life expectancy for HIVpositive patients (32). Alcohol and tobacco use have also been associated with poor adherence to antiretroviral therapy (ART) and the interaction between all those substances leading to a higher susceptibility to co-morbidities, opportunistic infections such as tuberculosis (TB) (33,34). In this study, hazardous/harmful alcohol consumption and binge drinking were both significantly associated with tobacco use (33). This indicates the need for targeted prevention actions such as smoking cessation treatment and alcohol reducing counseling, among key populations, particularly among key populations living with HIV. A systematic review of interventions to reduce alcohol use among MSM indicated that although interventions such as motivational interviewing appear to be effective among MSM, they are scarce (35).
Psychological distress was found to have a dose-response relationship with alcohol consumption. Severe psychological distress was at least twice higher among people with a hazardous/harmful alcohol  1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36  37  38  39  40  41  42  43  44  45  46  47  48  49  50  51  52  53  54  55  56  57  58  59  60   F  o  r  p  e  e  r  r  e  v  i  e  w  o  n  l  y   12 consumption and people who were binge drinking. This is consistent with other studies that found a relationship between alcohol and drug abuse and psychological symptoms such as depression, anxiety and suicidal ideation among key populations (29, 36,37). Consistent with our findings, a study conducted in Cambodia among MSM found that 38.8% had severe psychological distress and that severe psychological distress was associated with alcohol and drug use, poor self-reported quality of life and reduced condom use at last sex (36). In southern India, a study among FSW found a significant relationship between major depression and alcohol use (38). Another study among PLHIV in Uganda found that psychological distress was significantly associated with non-adherence to ART (39). This has implication for HIV prevention and further demonstrates the need for integrated services of mental health interventions, psychological support as well as substance abuse reduction program into HIV Very few studies have explored alcohol and tobacco consumption patterns among the three main key populations. This study found quite different patterns of consumption among the three groups, with MSM in this sample being the lowest at-risk group for hazardous/harmful alcohol consumption, binge drinking and tobacco use. DU on the other hand, appear to be most vulnerable to hazardous/harmful alcohol consumption, binge drinking and tobacco use, as well as the group with the highest prevalence of severe psychological distress. This could potentially indicate that there is a difference in coping strategies for key populations and that, behavioral interventions specifically geared towards MSM have elements that perhaps have successfully enhanced their capacity to cope with the stress among the most marginalized groups. For example, studies have demonstrated the effectiveness of community-based organizations (CBOs), peer-led interventions and community engagement in HIV prevention among MSM (40)(41)(42). It is important that targeted interventions be geared toward generating an interest for community building among DU.
Strengths of this study include the large sample size of the three main types of key populations. In addition, to our knowledge, this is the first study in Togo comparing alcohol and tobacco consumption in these key populations using standardized tools (AUDIT, Tobacco Questions for Surveys, and Kessler psychological distress scale). Finally, this study was completed in the eight main cities of Togo and used geographical mapping as well as RDS sampling, which could indicate that the findings of this study to reflect the national prevalence of alcohol and tobacco consumption among key populations.  1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36  37  38  39  40  41  42  43  44  45  46  47  48  49  50  51  52  53  54  55  56  57  58  59  60   F  o  r  p  e  e  r  r  e  v  i  e  w  o  n  l  y   13 However, there were few limitations including the fact that some variables such as childhood abuse, stigma, or recent trauma which could influence alcohol and tobacco consumption, have not been collected. Interactions between the different groups of key populations (i.e., DUs engaging in sex work, MSM who engage in sex work, sex workers who are also MSM) were also not collected. Furthermore, self-reported data used in this study, are prone to social desirability and recall bias. Despite these limitations, the results presented in this study make a unique contribution to the literature on alcohol and tobacco use among key populations in West Africa, especially since Togo shares similar characteristics with other countries of West Africa regarding the HIV epidemic (concentrated HIV epidemics with elevated HIV prevalences among key populations), access to treatment and prevention for key populations (3,43). The results could be generalized to other countries in West Africa.
Further research could further explore the relationship between alcohol, tobacco, depression and sexual risk behaviors and HIV infection among key populations. Qualitative studies could also explore the reasons for high alcohol and tobacco consumption among key populations.

Conclusion
Alcohol and tobacco use and abuse are highly prevalent among key populations. Psychological distress and being a DU were both significantly associated with alcohol and tobacco consumption. There is a need for mental health and substance abuse screening, referral and treatment to be addressed and fully integrated into HIV prevention services for key populations. Further research is also needed to explore, through qualitative and quantitative designs, the consequences and impact of alcohol and tobacco consumption, as well as mental health issues such as psychological distress on individuals and its burden in the HIV epidemic. ABA and FGK contributed equally to this paper. ABA, FGK, PAC and DKE conceived and designed the study with inputs from AJ. PJ, EKS, CAD, MS and TJB facilitated data collection and contributed to analysis of the data. ABA and FGK analyzed, interpreted the data and drafted the manuscript. PAC, AJ and DKE revised the manuscript for important intellectual content. All authors participated in the revision process and have approved the final version of the manuscript.

Competing interests
No competing interests to declare

Objectives
The aim of this study was to estimate alcohol and tobacco use prevalence and their correlates among female sex workers (FSW), men who have sex with men (MSM) and drug users (DU) in Togo.

Design, setting and participants
A cross-sectional bio-behavioral study was conducted among 2,115 MSM, FSW and DU in 2017 using a respondent-driven sampling (RDS) method, in the eight biggest towns of Togo. Selection criteria for the MSM were being male and having had oral or anal intercourse with a man in the previous 12 months; for FSW, being a female and having exchanged sex for money in the previous 12 months; and for DU, consuming heroin, cocaine or hashish for MSM, FSW and DU, respectively. All participants had be to at least 18 years old and residing in the territory for the past three months.

Results
The

Conclusion
Findings from this study demonstrate the need for the integration of mental health and substance abuse reduction interventions into HIV prevention programs, particularly those geared toward key populations.

Strengths and limitations of this study
 This study is among the first in sub-Saharan Africa exploring the patterns of alcohol and tobacco consumption among the three main groups of key populations  This study had a consistent sample size  The use of internationally validated instruments to assess alcohol and tobacco consumption, as well as psychological distress minimized bias  The main limitation of our study is that it was based on self-reported data which could be a potential source of recall bias or social desirability bias  Other risk factors associated with sexual risk behaviors and thus contributing to HIV transmission include alcohol and tobacco consumption. Alcohol, a psychoactive substance with dependenceproducing properties, has been an integral part of many cultures for several centuries (5). The harmful use of alcohol and its consequences make its consumption a public health problem. More than 200 disease and injury conditions including alcohol dependence, liver cirrhosis, cancers and injuries are the consequences of the harmful use of alcohol (5). In 2012, it was reported that 5.9% of all global deaths and 5.1% of the global burden of disease and injury were the consequences of harmful alcohol consumption (5). Recent research studies have also uncovered a causal relationship between the harmful use of alcohol and infectious diseases, including HIV (5-7). This relation could be attributed to the fact that alcohol influences cognitive abilities and decision making, and affects condom negotiation and correct condom use (8). Among key populations, particularly sex workers, alcohol consumption is seen as a sexual enhancer and work requirement which in many cases leads to an increased likelihood of unprotected sex, economic loss, interference with family responsibilities and sexual violence (7,9,10).
Tobacco consumption is also one of the biggest public health challenges of the 21 st century, with a clear, causal link between tobacco use and health. It is estimated that tobacco use kills half of its users and is responsible for the death of more than 7 million people a year. Approximately 80% of tobacco users live in low and middle income countries (11). Tobacco use is one the main risk factors for lung cancer, disability and death from non-communicable chronic diseases, and also an increased risk of death from communicable diseases (12,13). For people living with HIV, tobacco use is a risk factor for HIV-related comorbidities and premature death (14). Estimates in Togo put the prevalence of alcohol and tobacco consumption at 53.7% and 8.5% respectively, in the general population (15).    (associations and hot spots) specific to each group of key population were identified during preliminary visits with the help of leaders from these communities. DU and FSW were recruited in drugdealing/consumption locations and brothels (licensed or not), respectively. MSM were recruited using a Respondent Driven Sampling (RDS) method (17,18). MSM community leaders were the first "seeds".
A total of 28 seeds were identified at first based on their roles in their community and on their representativeness. Each seed from the first wave selected had to represent at least one MSM sub-group, based on how MSM self-identify as bisexuals or gays (19,20). Each participant was then given three coupons with a unique identification code to recruit three other seeds in their network until the required sample size for each group was reached. Inclusion criteria for the three groups were being 18 years or older, living/working/studying in Togo for a minimum of 3 months at the time of the study, and being in possession of a recruitment coupon. In addition to these criteria, criteria specific to MSM were having had anal and/or oral sex with a man in the previous 12 months, for FSW having had sex in exchange for money as a compensation in the previous 12 months and for DU, consuming heroin, cocaine or hashish at the time of the study.

Sample size estimation
The sample size estimation was based on the estimated prevalence of hazardous alcohol drinking among key populations of 9.1% (21). We also took into account the prevalence of tobacco use, with the assumption that tobacco use prevalence in the key populations would be twice that of the general population. Hence, with a tobacco use prevalence of 6.8% in the general population, the expected prevalence of tobacco use among key populations was 13.6% (15). With a precision of 3% and an assumption of 10% of missing data, the minimum sample size was estimated at 552 participants per group at a minimum. Thus, to allow a comparison between groups, the total sample size estimated for the three groups of key populations was 1,656.

Study procedures
After eligibility screening and written informed consent approval, trained study staff (medical students) administered a structured and standardized questionnaire during a face-to-face interview. The interviews took place in the MSM community-based organizations for the MSM, for the FSW, in selected bars around the main "hot spots" from which they were recruited and for the DU, recruitment occurred in the smoking spots in the "ghettos". The questionnaire was constructed based on validated tools such as the Alcohol Use Disorders Identification Test (AUDIT) (22) and a subset of the Tobacco Questions for Surveys (23) to assess alcohol and tobacco consumption respectively. The Kessler Psychological Distress Scale (K10) (24) was used to measure psychological distress and the Family Health International (FHI) 360 validated guide for bio-behavioral surveys (25) was adapted to collect information on socio-demographic characteristics, risky sexual behaviors, STIs, HIV prevention methods, HIV testing history, access to health care services, and HIV knowledge. The questionnaires were used across the three populations with slight adaptations depending on the population.

Scores and operational definitions
The AUDIT was used to assess alcohol consumption. The AUDIT is a set of 10-item standardized screening instrument measuring self-reported alcohol use in the past 12 months, alcohol dependence symptoms, and alcohol-related problems to screen for excessive drinking. Each question of the AUDIT can obtain a score from zero (0) to four (4). A score ≥8 for men and ≥7 for women indicates hazardous/harmful drinking, while a score of 0 indicates a non-drinker; moderate alcohol use lies inbetween (22,26,27). Binge drinking or heavy episodic drinking was defined as the consumption of six or more alcohol drinks on at least one occasion in the past 30 days (third item of the AUDIT) (22).
Tobacco use was assessed using six questions indicating participants' smoking habits, frequency of smoking, history of smoking, type of products smoked and attempts at stopping to smoke (23).
The Kessler Psychological Distress Scale (K10) was used to measure psychological distress. This scale has been examined and validated among several populations and aims at measuring anxiety and depression with a 10-item questionnaire, each question pertaining to an emotional state and a five-level response scale for each response. The score obtained from the scale allows to categorize participants into four categories of psychological distress: severe (score ≥ 30), moderate (score: 25-29), mild (score: [20][21][22][23][24] and none (score < 20) (28).

Laboratory testing
Written informed consent was obtained prior to blood sample collection. Among the 2,115 key populations recruited for the study, 91.8% gave their written informed consent for blood sample collection. Blood samples were collected to test for HIV and Syphilis using SD Biolane Duo (Abbott, Santa Clara, CA, USA). Each HIV positive test was confirmed with another HIV rapid test, the First

Statistical analysis
Descriptive statistics were performed and results were presented with frequency tabulations and percentages. Prevalences were estimated with their 95% confidence interval (95%CI). Univariate and multivariate logistic regression were performed to identify factors associated with: i) hazardous/harmful alcohol consumption, ii) binge drinking and iii) current tobacco consumption. For model building, characteristics that had a p-value <0.20 in univariate analysis were considered for the full multivariable models, which were then finalized using a stepwise, backward elimination approach. The three models did not include the variable "sex" as the four groups were already categorized according to sex. All analyses were performed using R® software.

Ethical consideration
This study was approved by the "Comité de Bioéthique pour la Recherche en Santé (CBRS)" (Bioethics Committee for Health Research) from the Togo Ministry of Health. Participants provided written consent prior to participation. Potential participants were told about the study purpose and procedures, potential risks and protections, and compensation. Informed consent was documented with signed consent forms.

Patient and Public Involvement
Members of key populations were involved during the study design and data collection phases of the study. They were consulted prior to the study for their input on the best method to reach out to key populations and they were actively involved in the recruitment process.  Socio-demographic and health characteristics are summarized in Table 1.

Alcohol and tobacco consumption
Alcohol and tobacco consumption patterns are presented in Table 2. Overall, the prevalence of alcohol consumption among the three groups was 64.8%. Most participants were identified as having a hazardous/harmful alcohol consumption (n=813; 38.4%), with the highest proportion among DU (62.4% among DU; 36.7% among FSW; and 20.9% among MSM; p <0.001). More than a quarter of FSW (n=275; 29.4%) were moderate drinkers. The MSM subgroup had the highest proportion of non-drinkers (n=338; 52.7%), followed by FSW (n=318; 33.9%). The overall prevalence of binge drinking was 45.5% and was the highest among DU (67.0%) ( Table 2).
The prevalence of tobacco consumption was 30.6% among the three groups. DU had the highest proportion of smokers (80.8%). The highest proportion of non-smokers were FSW (n=821; 87.6%), followed by MSM (n=544, 84.9%). Of the people who smoked, 63.1% were smoking every day, including 79.0% of DU, 42.2% of FSW and 16.5% of MSM. Table 3

Discussion
The aim of this study was to assess the prevalence of hazardous/harmful, binge alcohol consumption as well as tobacco consumption, and explore correlates of heavy alcohol consumption and tobacco use in three key populations in Togo. We observed a high prevalence of hazardous/harmful alcohol consumption and binge drinking. Alcohol consumption was frequent among FSW and much more among DU. In addition, there was a dose-response effect relationship between alcohol consumption and psychological distress across all three populations. Tobacco use was highly prevalent among DU and among people who had a hazardous/harmful alcohol consumption.
Alcohol consumption is highly prevalent among key populations groups: more than half of the sample were categorized as moderate or hazardous drinkers. This has been corroborated in the literature among key population groups. In a recent study in Kenya, among 1,476 MSM, 44% of the sample had a hazardous alcohol consumption, and, no relationship was found between alcohol and tobacco consumption and HIV infection (29). In another study among 3,588 MSM in China, alcohol prevalence was 56.1% with 16.8% of them being binge drinkers and 14.4% being recent hazardous drinkers, using the WHO AUDIT-C scale (30). Recent alcohol misuse was associated with increased sexual and HIV/syphilis risks as well as sexual risk behaviors including alcohol use before sex, sex without condoms and multiple concurrent partnerships. A prospective cohort study among 1,027 FSW in Uganda found that 78% of the sample reported using alcohol with 71% admitting to using alcohol at least once a week, with a reduced prevalence of 54% after two years of intervention (31). This emphasizes the need for alcohol risk reduction programs and programs specifically focused on the adoption of safer drinking practices integrated into HIV prevention packages and geared towards highly exposed groups (30,31).
Alcohol and tobacco consumption are particularly relevant to people living with HIV (PLHIV). Studies have demonstrated a negative impact of alcohol, tobacco and drug use on life expectancy for HIVpositive patients (32). Alcohol and tobacco use have also been associated with poor adherence to antiretroviral therapy (ART) and the interaction between all those substances leading to a higher susceptibility to co-morbidities, opportunistic infections such as tuberculosis (TB) (33,34). In this study, hazardous/harmful alcohol consumption and binge drinking were both significantly associated with tobacco use (33). This indicates the need for targeted prevention actions such as smoking cessation treatment and alcohol reducing counseling, among key populations, particularly among key populations living with HIV. A systematic review of interventions to reduce alcohol use among MSM indicated that although interventions such as motivational interviewing appear to be effective among MSM, they are scarce (35).
Psychological distress was found to have a dose-response relationship with alcohol consumption. Severe psychological distress was at least twice higher among people with a hazardous/harmful alcohol consumption and people who were binge drinking. This is consistent with other studies that found a relationship between alcohol and drug abuse and psychological symptoms such as depression, anxiety and suicidal ideation among key populations (29, 36,37). Consistent with our findings, a study conducted in Cambodia among MSM found that 38.8% had severe psychological distress and that severe psychological distress was associated with alcohol and drug use, poor self-reported quality of life and reduced condom use at last sex (36). In southern India, a study among FSW found a significant relationship between major depression and alcohol use (38). Another study among PLHIV in Uganda found that psychological distress was significantly associated with non-adherence to ART (39). This has implication for HIV prevention and further demonstrates the need for integrated services of mental health interventions, psychological support as well as substance abuse reduction program into HIV Strengths of this study include the large sample size of the three main types of key populations. In addition, to our knowledge, this is the first study in Togo comparing alcohol and tobacco consumption in these key populations using standardized tools (AUDIT, Tobacco Questions for Surveys, and Kessler psychological distress scale). Finally, this study was completed in the eight main cities of Togo and used geographical mapping as well as RDS sampling, which could indicate that the findings of this study to reflect the national prevalence of alcohol and tobacco consumption among key populations. However, there were few limitations including the fact that some variables such as childhood abuse, stigma, or recent trauma which could influence alcohol and tobacco consumption, have not been collected. Interactions between the different groups of key populations (i.e., DUs engaging in sex work, MSM who engage in sex work, sex workers who are also MSM) were also not collected. Furthermore, self-reported data used in this study, are prone to social desirability and recall bias. Despite these limitations, the results presented in this study make a unique contribution to the literature on alcohol and tobacco use among key populations in West Africa, especially since Togo shares similar characteristics with other countries of West Africa regarding the HIV epidemic (concentrated HIV epidemics with elevated HIV prevalences among key populations), access to treatment and prevention for key populations (3,43). The results could be generalized to other countries in West Africa.
Further research could further explore the relationship between alcohol, tobacco, depression and sexual risk behaviors and HIV infection among key populations. Qualitative studies could also explore the reasons for high alcohol and tobacco consumption among key populations.

Conclusion
Alcohol and tobacco use and abuse are highly prevalent among key populations. Psychological distress and being a DU were both significantly associated with alcohol and tobacco consumption. There is a need for mental health and substance abuse screening, referral and treatment to be addressed and fully integrated into HIV prevention services for key populations. Further research is also needed to explore, through qualitative and quantitative designs, the consequences and impact of alcohol and tobacco consumption, as well as mental health issues such as psychological distress on individuals and its contribution to the HIV epidemic.

Objectives
The aim of this study was to estimate alcohol and tobacco use prevalence and their correlates among female sex workers (FSW), men who have sex with men (MSM) and drug users (DU) in Togo.

Design, setting and participants
A cross-sectional bio-behavioral study was conducted among 2,115 MSM, FSW and DU in 2017 using a respondent-driven sampling (RDS) method, in the eight biggest towns of Togo. Selection criteria for the MSM were being male and having had oral or anal intercourse with a man in the previous 12 months; for FSW, being a female and having exchanged sex for money in the previous 12 months; and for DU, consuming heroin, cocaine or hashish for MSM, FSW and DU, respectively. All participants had be to at least 18 years old and residing in the territory for the past three months.

Results
The

Conclusion
Findings from this study demonstrate the need for the integration of mental health and substance abuse reduction interventions into HIV prevention programs, particularly those geared toward key populations.

Strengths and limitations of this study
 This study is among the first in sub-Saharan Africa exploring the patterns of alcohol and tobacco consumption among the three main groups of key populations  This study had a consistent sample size  The use of internationally validated instruments to assess alcohol and tobacco consumption, as well as psychological distress minimized bias  The main limitation of our study is that it was based on self-reported data which could be a potential source of recall bias or social desirability bias  1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36  37  38  39  40  41  42  43  44  45  46  47  48  49  50  51  52  53  54  55  56  57  58  59  However, in key populations, populations at higher risk of HIV such as sex workers, men who have sex with men (MSM) and injection drug users, the reported prevalence rates are disproportionally high compared to those of the general population (2,3). In Togo, HIV prevalence among key populations ranges from 11% to 13% compared to 2.1% in the general population (4). Several biological, behavioral and structural risk factors are associated with this high HIV rate among key populations: unprotected sex, presence of other Sexually Transmitted Infections (STIs), lack of access to condoms, multiple concurrent sex partners (males and females for MSM), lack of access to health care and prevention services, physical and sexual violence, challenging legal and sociopolitical environment, poverty, sociopolitical stigma and discrimination (2,3).
Other risk factors associated with sexual risk behaviors and thus contributing to HIV transmission include alcohol and tobacco consumption. Alcohol, a psychoactive substance with dependenceproducing properties, has been an integral part of many cultures for several centuries (5). The harmful use of alcohol and its consequences make its consumption a public health problem. More than 200 disease and injury conditions including alcohol dependence, liver cirrhosis, cancers and injuries are the consequences of the harmful use of alcohol (5). In 2012, it was reported that 5.9% of all global deaths and 5.1% of the global burden of disease and injury were the consequences of harmful alcohol consumption (5). Recent research studies have also uncovered a causal relationship between the harmful use of alcohol and infectious diseases, including HIV (5)(6)(7). This relation could be attributed to the fact that alcohol influences cognitive abilities and decision making, and affects condom negotiation and correct condom use (8). Among key populations, particularly sex workers, alcohol consumption is seen as a sexual enhancer and work requirement which in many cases leads to an increased likelihood of unprotected sex, economic loss, interference with family responsibilities and sexual violence (7,9,10).
A total of 28 seeds were identified at first based on their roles in their community and on their representativeness. Each seed from the first wave selected had to represent at least one MSM sub-group, based on how MSM self-identify as bisexuals or gays (19,20). Each participant was then given three coupons with a unique identification code to recruit three other seeds in their network until the required sample size for each group was reached. Inclusion criteria for the three groups were being 18 years or older, living/working/studying in Togo for a minimum of 3 months at the time of the study, and being in possession of a recruitment coupon. In addition to these criteria, criteria specific to MSM were having had anal and/or oral sex with a man in the previous 12 months, for FSW having had sex in exchange for money as a compensation in the previous 12 months and for DU, consuming heroin, cocaine or hashish at the time of the study.

Sample size estimation
The sample size estimation was based on the estimated prevalence of hazardous alcohol drinking among key populations of 9.1% (21). We also took into account the prevalence of tobacco use, with the assumption that tobacco use prevalence in the key populations would be twice that of the general population. Hence, with a tobacco use prevalence of 6.8% in the general population, the expected prevalence of tobacco use among key populations was 13.6% (15). With a precision of 3% and an assumption of 10% of missing data, the minimum sample size was estimated at 552 participants per group at a minimum. Thus, to allow a comparison between groups, the total sample size estimated for the three groups of key populations was 1,656.

Study procedures
After eligibility screening and written informed consent approval, trained study staff (medical students) administered a structured and standardized questionnaire during a face-to-face interview. The interviews took place in the MSM community-based organizations for the MSM, for the FSW, in selected bars around the main "hot spots" from which they were recruited and for the DU, recruitment occurred in the smoking spots in the "ghettos". The questionnaire was constructed based on validated tools such as the Alcohol Use Disorders Identification Test (AUDIT) (22) and a subset of the Tobacco Questions for Surveys (23) to assess alcohol and tobacco consumption respectively. The Kessler Psychological Distress Scale (K10) (24) was used to measure psychological distress and the Family Health International (FHI) 360 validated guide for bio-behavioral surveys (25) was adapted to collect information on socio-demographic characteristics, risky sexual behaviors, STIs, HIV prevention methods, HIV testing history, access to health care services, and HIV knowledge. The questionnaires were used across the three populations with slight adaptations depending on the population.

Scores and operational definitions
The AUDIT was used to assess alcohol consumption. The AUDIT is a set of 10-item standardized screening instrument measuring self-reported alcohol use in the past 12 months, alcohol dependence symptoms, and alcohol-related problems to screen for excessive drinking. Each question of the AUDIT can obtain a score from zero (0) to four (4). A score ≥8 for men and ≥7 for women indicates hazardous/harmful drinking, while a score of 0 indicates a non-drinker; moderate alcohol use lies inbetween (22,26,27). Binge drinking or heavy episodic drinking was defined as the consumption of six or more alcohol drinks on at least one occasion in the past 30 days (third item of the AUDIT) (22).
Tobacco use was assessed using six questions indicating participants' smoking habits, frequency of smoking, history of smoking, type of products smoked and attempts at stopping to smoke (23).
The Kessler Psychological Distress Scale (K10) was used to measure psychological distress. This scale has been examined and validated among several populations and aims at measuring anxiety and depression with a 10-item questionnaire, each question pertaining to an emotional state and a five-level response scale for each response. The score obtained from the scale allows to categorize participants into four categories of psychological distress: severe (score ≥ 30), moderate (score: 25-29), mild (score: [20][21][22][23][24] and none (score < 20) (28).

Statistical analysis
Descriptive statistics were performed and results were presented with frequency tabulations and percentages. Prevalences were estimated with their 95% confidence interval (95%CI). Univariate and multivariate logistic regression were performed to identify factors associated with: i) hazardous/harmful alcohol consumption, ii) binge drinking and iii) current tobacco consumption. For model building, characteristics that had a p-value <0.20 in univariate analysis were considered for the full multivariable models, which were then finalized using a stepwise, backward elimination approach. The three models did not include the variable "sex" as the four groups were already categorized according to sex. All analyses were performed using R® software.

Ethical consideration
This study was approved by the "Comité de Bioéthique pour la Recherche en Santé (CBRS)" (Bioethics Committee for Health Research) from the Togo Ministry of Health. Participants provided written consent prior to participation. Potential participants were told about the study purpose and procedures, potential risks and protections, and compensation. Informed consent was documented with signed consent forms.

Patient and Public Involvement
Members of key populations were involved during the study design and data collection phases of the study. They were consulted prior to the study for their input on the best method to reach out to key populations and they were actively involved in the recruitment process.  1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36  37  38  39  40  41  42  43  44  45  46  47  48  49  50  51  52  53  54  55  56  57  58  59  60   F  o  r  p  e  e  r  r  e  v  i  e  w  o  n  l  y   9 Newly diagnosed HIV positive patients were referred to an HIV clinic for HIV treatment and care.

Socio-demographic characteristics
Socio-demographic and health characteristics are summarized in Table 1.

Discussion
The aim of this study was to assess the prevalence of hazardous/harmful, binge alcohol consumption as well as tobacco consumption, and explore correlates of heavy alcohol consumption and tobacco use in three key populations in Togo. We observed a high prevalence of hazardous/harmful alcohol consumption and binge drinking. Alcohol consumption was frequent among FSW and much more among DU. In addition, there was a dose-response effect relationship between alcohol consumption and psychological distress across all three populations. Tobacco use was highly prevalent among DU and among people who had a hazardous/harmful alcohol consumption.
Alcohol consumption is highly prevalent among key populations groups: more than half of the sample were categorized as moderate or hazardous drinkers. This has been corroborated in the literature among key population groups. In a recent study in Kenya, among 1,476 MSM, 44% of the sample had a hazardous alcohol consumption, and, no relationship was found between alcohol and tobacco consumption and HIV infection (29). In another study among 3,588 MSM in China, alcohol prevalence was 56.1% with 16.8% of them being binge drinkers and 14.4% being recent hazardous drinkers, using the WHO AUDIT-C scale (30). Recent alcohol misuse was associated with increased sexual and HIV/syphilis risks as well as sexual risk behaviors including alcohol use before sex, sex without condoms and multiple concurrent partnerships. A prospective cohort study among 1,027 FSW in Uganda found that 78% of the sample reported using alcohol with 71% admitting to using alcohol at least once a week, with a reduced prevalence of 54% after two years of intervention (31). This emphasizes the need for alcohol risk reduction programs and programs specifically focused on the adoption of safer drinking practices integrated into HIV prevention packages and geared towards highly exposed groups (30,31).
Alcohol and tobacco consumption are particularly relevant to people living with HIV (PLHIV). Studies have demonstrated a negative impact of alcohol, tobacco and drug use on life expectancy for HIVpositive patients (32). Alcohol and tobacco use have also been associated with poor adherence to antiretroviral therapy (ART) and the interaction between all those substances leading to a higher susceptibility to co-morbidities, opportunistic infections such as tuberculosis (TB) (33,34). In this study, hazardous/harmful alcohol consumption and binge drinking were both significantly associated with tobacco use (33). This indicates the need for targeted prevention actions such as smoking cessation treatment and alcohol reducing counseling, among key populations, particularly among key populations living with HIV. A systematic review of interventions to reduce alcohol use among MSM indicated that although interventions such as motivational interviewing appear to be effective among MSM, they are scarce (35).
Psychological distress was found to have a dose-response relationship with alcohol consumption. Severe psychological distress was at least twice higher among people with a hazardous/harmful alcohol  1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36  37  38  39  40  41  42  43  44  45  46  47  48  49  50  51  52  53  54  55  56  57  58  59  60   F  o  r  p  e  e  r  r  e  v  i  e  w  o  n  l  y   12 consumption and people who were binge drinking. This is consistent with other studies that found a relationship between alcohol and drug abuse and psychological symptoms such as depression, anxiety and suicidal ideation among key populations (29, 36,37). Consistent with our findings, a study conducted in Cambodia among MSM found that 38.8% had severe psychological distress and that severe psychological distress was associated with alcohol and drug use, poor self-reported quality of life and reduced condom use at last sex (36). In southern India, a study among FSW found a significant relationship between major depression and alcohol use (38). Another study among PLHIV in Uganda found that psychological distress was significantly associated with non-adherence to ART (39). This has implication for HIV prevention and further demonstrates the need for integrated services of mental health interventions, psychological support as well as substance abuse reduction program into HIV Very few studies have explored alcohol and tobacco consumption patterns among the three main key populations. This study found quite different patterns of consumption among the three groups, with MSM in this sample being the lowest at-risk group for hazardous/harmful alcohol consumption, binge drinking and tobacco use. DU on the other hand, appear to be most vulnerable to hazardous/harmful alcohol consumption, binge drinking and tobacco use, as well as the group with the highest prevalence of severe psychological distress. This could potentially indicate that there is a difference in coping strategies for key populations and that, behavioral interventions specifically geared towards MSM have elements that perhaps have successfully enhanced their capacity to cope with the stress among the most marginalized groups. For example, studies have demonstrated the effectiveness of community-based organizations (CBOs), peer-led interventions and community engagement in HIV prevention among MSM (40)(41)(42). It is important that targeted interventions be geared toward generating an interest for community building among DU.
Strengths of this study include the large sample size of the three main types of key populations. In addition, to our knowledge, this is the first study in Togo comparing alcohol and tobacco consumption in these key populations using standardized tools (AUDIT, Tobacco Questions for Surveys, and Kessler psychological distress scale). Finally, this study was completed in the eight main cities of Togo and used geographical mapping as well as RDS sampling, which could indicate that the findings of this study to reflect the national prevalence of alcohol and tobacco consumption among key populations.  1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36  37  38  39  40  41  42  43  44  45  46  47  48  49  50  51  52  53  54  55  56  57  58  59  60   F  o  r  p  e  e  r  r  e  v  i  e  w  o  n  l  y   13 However, there were few limitations including the fact that some variables such as childhood abuse, stigma, or recent trauma which could influence alcohol and tobacco consumption, have not been collected. Interactions between the different groups of key populations (i.e., DUs engaging in sex work, MSM who engage in sex work, sex workers who are also MSM) were also not collected. Furthermore, self-reported data used in this study, are prone to social desirability and recall bias. Despite these limitations, the results presented in this study make a unique contribution to the literature on alcohol and tobacco use among key populations in West Africa, especially since Togo shares similar characteristics with other countries of West Africa regarding the HIV epidemic (concentrated HIV epidemics with elevated HIV prevalences among key populations), access to treatment and prevention for key populations (3,43). The results could be generalized to other countries in West Africa.
Further research could further explore the relationship between alcohol, tobacco, depression and sexual risk behaviors and HIV infection among key populations. Qualitative studies could also explore the reasons for high alcohol and tobacco consumption among key populations.

Conclusion
Alcohol and tobacco use and abuse are highly prevalent among key populations. Psychological distress and being a DU were both significantly associated with alcohol and tobacco consumption. There is a need for mental health and substance abuse screening, referral and treatment to be addressed and fully integrated into HIV prevention services for key populations. Further research is also needed to explore, through qualitative and quantitative designs, the consequences and impact of alcohol and tobacco consumption, as well as mental health issues such as psychological distress on individuals and its contribution to the HIV epidemic.  1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31  32  33  34  35  36  37  38  39  40  41  42  43  44  45  46  47  48  49  50  51  52  53  54  55  56  57  58  59  ABA and FGK contributed equally to this paper. ABA, FGK, PAC and DKE conceived and designed the study with inputs from AJ. PJ, EKS, CAD, MS and TJB facilitated data collection and contributed to analysis of the data. ABA and FGK analyzed, interpreted the data and drafted the manuscript. PAC, AJ and DKE revised the manuscript for important intellectual content. All authors participated in the revision process and have approved the final version of the manuscript.