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The therapeutic relationship between a client and dietitian: A systematic integrative review of empirical literature

Abstract Aim Scientific evidence underpins dietetics practice; however, evidence of how the therapeutic relationship influences outcomes is limited. This integrative review aims to provide a comprehensive overview of the topic of the therapeutic relationship between clients and dietitians in the individual counselling context by summarising empirical literature into qualitative themes. Methods An electronic literature search of the Cumulative Index of Nursing and Allied Health Literature, PsychInfo, Scopus and Web of Science databases was conducted in October 2018 and repeated in February 2021. Studies were included if they explicitly referred to the therapeutic relationship (or associated terms), were based on study data and available in full text. Extracted data were checked by a second researcher and the methodological quality was evaluated independently by two researchers using the Mixed Methods Appraisal Tool. An iterative process of qualitatively coding, categorising and comparing data to examine recurring themes was applied. Results Seventy‐six studies met the inclusion criteria. Five themes were identified which showed the extent and nature of research in this area. Studies revealed the therapeutic relationship: (i) is valued within clinical dietetic practice, (ii) involves complex and multifactorial interactions, (iii) is perceived as having a positive influence, (iv) requires skills training and (v) is embedded in practice models and tools. Conclusion Studies show the therapeutic relationship is a valued and multifactorial component of clinical dietetic practice and is perceived to positively influence the client and dietitian. Observational data are needed to assess the extent to which the strength of the therapeutic relationship might contribute to clients' health outcomes.


| INTRODUCTION
Dietetics is an evidence-based profession where peerreviewed, scientific research underpins practice. The International Confederation of Dietetic Associations describes evidence-based practice as a skill for dietitians to guide their decision-making. They describe dietitians having to combine an assessment of how valid, applicable and important evidence is with their own expertise and the client's values and circumstances. 1 Hence, an evidence-based approach requires critical skills of the dietitian in understanding, evaluating and applying scientific knowledge in a meaningful way for the client. In Australia, dietitians are required to practise within an evidence-based approach as outlined by the Statement of Ethical Practice 2 and National Competency Standards, 3 a requirement that is supported by the International Code of Good Practice published by the International Confederation of Dietetic Associations. 4 Thus, practising in a way that is built upon credible, scientific evidence is fundamental to the dietetic profession. This evidence should also relate to how effective practice is conducted, including consideration of the therapeutic relationship with clients.
Although governing documents depict the therapeutic relationship as crucial for clinical dietetic practice, comprehensive descriptions of its key components are scarce. 3,5 For example, the competency standards for dietitians in Australia state dietitians must 'build an effective relationship' with little articulation of what an effective relationship might look like. 3 In earlier research, the authors have shown that meaningful therapeutic relationship development is a complex and multi-faceted process. 6 However, prior to this, many studies simply identified stand-alone qualities (such as 'trust') as important for relationship development without detailed descriptions of the process of meaningful relationship development as a whole. [7][8][9] The limited descriptions of important relationship components may in part be due to the heavy influence of biomedical and nutritional sciences as sources of evidence for practice. A qualitative study that explored dietitians' perceptions of evidencebased practice reported that dietitians did not perceive knowledge about communication skills to be 'evidencebased'. 10 In contrast to biomedical and nutritional information, dietitians did not feel they needed to retrieve information from the scientific literature to understand the evidence-base around communication skills. These skills were instead considered as 'know-how', gained through professional development opportunities rather than scientific literature. 10 The therapeutic relationship is integral to communication and counselling practices, as they are pivotal to how effectively the client and dietitian engage and are able to work together. 11 However, these findings suggest dietitians may also not consider knowledge and skills in the development of therapeutic relationships as part of the 'evidence-based' reference framework. This suggests a need for more scientific knowledge of therapeutic relationships, particularly as it can indeed provide evidence that informs practice.
Exploratory research may be required in the first instance. Integrative literature reviews are appropriate as they can provide a more comprehensive understanding of a specific healthcare phenomenon by summarising relevant literature and allowing various methodologies to be included. 12 Integrative reviews on therapeutic relationships can be found in other disciplines such as nursing, physiotherapy and occupational therapy, but are limited in dietetics. [13][14][15][16][17] One integrative review of published studies from 1997 to 2016, focused on patient-centred care in dietetics. 18 It highlighted the significance of the therapeutic relationship and noted this relationship as an important dimension in delivering patient-centred healthcare. Although patient-centred care and the therapeutic relationship are related concepts, the integrative review on patient-centred care did not comprehensively focus on the therapeutic relationship. The inclusion criteria specified 'relationship' only and did not include other terms known to represent the phenomenon of the therapeutic relationship, for example, 'alliance', 'connection' and 'rapport'. Dietetic students were also excluded and hence the review on patient-centred care did not capture literature describing how students might be trained in therapeutic relationship development. There remains a need to review research that comprehensively focuses on the concept of the therapeutic relationship (including other like terms), particularly those published prior to 1997 and since 2016.
The integrative review reported here addresses the broad question 'What does research on the therapeutic relationship tell us about the phenomenon in clinical dietetic practice?'. The aim of this study was to provide a comprehensive overview of the topic of the therapeutic relationship between clients and dietitians in the individual counselling context by summarising empirical literature into qualitative themes. The term 'therapeutic relationship' is widely used across healthcare literature and hence is used throughout to refer to the purposeful relationship between a client and dietitian for the client's therapeutic benefit. 19 'Therapeutic alliance' is also used, as it is a term used within the psychology discipline that refers to a component of the therapeutic relationship. 20

| METHODS
This integrative review was written in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. 21 The integrative review methodology was guided by the work of Whittemore and Knafl who specify five key stages: problem identification, literature search, data evaluation, data analysis and data presentation. 12 The approach has been applied previously by Sladdin et al. in a study of patient-centred care in the dietetic context. 18 A systematic electronic literature search was conducted in October 2018 and repeated in February 2021 to account for studies published after the original search date. The terms 'dietitian', 'client' and 'relationship' were used as a foundation to identify other relevant search terms. To ensure a comprehensive list of terms was achieved a health sciences librarian was consulted and the online version of the Oxford thesaurus was used in addition to the first author's knowledge of terminology expressed in the literature. 22 Medical subject headings (MeSH) were also utilised to ensure key terms were included and truncated appropriately, for example, searching for 'relation*' rather than 'relationship'. Search terms corresponding to the dietitian and client included: 'dietitian', 'dietician', 'nutritionist', 'client' and 'patient'. Search terms corresponding to 'relationship' included: 'relation*', 'alliance', 'partner*', 'collaborat*', 'connect*', 'rapport', 'bond*' and 'interaction*'. Boolean connectors 'AND' and 'OR' were used. Four electronic databases were searched: Cumulative Index of Nursing and Allied Health Literature (CINAHL), PsychInfo, Scopus and Web of Science. Research shows electronic database searches may yield only half of the eligible studies and therefore other strategies were applied, including ancestry searching and hand searching of key dietetic journals. 23 Google Scholar and Scopus databases were used to attain articles identified through ancestry and hand searching. All citations obtained through searching were imported into EndNote for data management purposes. 24 One researcher screened the titles and abstracts of articles according to the inclusion and exclusion criteria. Studies were included if they: (i) explicitly referred to the relationship, alliance, partnership, collaboration, connection, rapport, bond or interaction between a client and dietitian, nutritionist or nutrition and/or dietetic student concerning the study being reported, (ii) were empirical (that is based on data collected for a study), and (iii) were available as full text. Studies were excluded if they referred to the relationship (as outlined in the inclusion criteria above) but only with regard to group-based interventions, or described a multidisciplinary context but it was unclear if the relationship was between a client and dietitian, nutritionist or nutrition and/or dietetic student specifically. No exclusion criteria for study language or year was applied to maximise the opportunity for relevant data to be captured. English translations of the full-text version of published articles were requested from authors via email. Articles were obtained and each fulltext article was read by the researcher to determine if they met the inclusion criteria.
Data were systematically extracted into a Microsoft Excel 25 table that included study authors, year and country, study design and aim, inclusion criteria, sample, data collection and analysis methods and findings concerning the therapeutic relationship or associated terms. One researcher extracted all data which were checked by a second researcher using a method for source data verification (that is comparing original documents to recorded data). 26 The percentage of errors identified was within the acceptable error rate (≤5%) meaning no further checking of data was required. 26 The methodological quality of each study identified in the initial search was independently scored by two researchers using the Mixed Methods Appraisal Tool (MMAT). This was performed due to the subjectivity of the MMAT. 27 Researchers discussed differences between scores and an agreed score was decided. Justification for the agreed scores was documented and used to score studies identified in the repeated search.
Following processes outlined by Whittemore and Knafl, the data were 'ordered, coded, categorised and summarised' by one researcher and refined through discussions with the interdisciplinary research team (dietetics and psychology). 12 Initially, studies were ordered according to whether they referred to the 'relationship' or 'alliance', or associated terms such as 'connection'. Data concerning the terms 'relationship' and 'alliance' were analysed together because both are established terms in the psychology discipline with evidence-based constructs (e.g., psychologist Bordin's 'working alliance'). 20 These terms were initially analysed separately from other terms in anticipation of a possible difference in findings given their link to evidence-based constructs. Data were then ordered according to study design (either qualitative, quantitative, mixed methods or literature reviews).
Whittemore and Knafl suggest applying the constant comparative method particularly for analysing data from different methodologies. 12 All extracted data were copied directly from the data extraction table for coding by one researcher. Data concerning the relationship and alliance were coded first, followed by data concerning associated terms. The coding process began with assigning initial codes, which were codes that described evidence in the data extract for either 'relationship', 'alliance' or associated terms. These codes were then compared, where similarities between codes were identified and consequently grouped together to form common themes. 12 This process involved re-reading codes and adjusting preliminary themes to ensure the themes reflected the codes. Once themes were developed for data within each study design, they were then compared across study designs and merged where similarities were seen (e.g., quantitative and qualitative data showing the relationship is important). Data were collated across study designs to reflect merged themes. 12 This process occurred separately as part of the analyses for both primary terms ('relationship' and 'alliance') and associated terms (e.g., 'connection').
Established themes within both primary and associated terms analyses were compared, with similarities and differences documented. These notes allowed identification of major themes across both analyses, and where appropriate these were adapted to reflect data from both analyses. Following this, data were collated and findings were reviewed to confirm each theme. The final phase of the analysis involved drafting a summation of each theme where its meaning was further crystallised. 12 Meetings were also held with the interdisciplinary research team where the emerging analysis was discussed, critiqued and refined. This team consisted of researchers from both dietetics and psychology and allowed for themes that were developed from a dietetics lens to be challenged from a psychology perspective. Additional notes were kept by the researcher to document the emerging analysis, analytical decisions and possible directions for further analysis. 12

| RESULTS
From 2433 studies identified for screening, 76 studies were included ( Figure 1). Most quantitative studies were descriptive, and predominantly utilised surveys (n = 21) and ratings of observed practice (n = 7). One study involved a secondary analysis of control and intervention data from a randomised controlled trial. Qualitative study designs mostly utilised interviews (n = 26) and focus groups (n = 9). Most studies were conducted in Australia (n = 27) or the USA (n = 18), and published between 2010 and 2020 (n = 50). Most studies had between 11 and 395 participants (n = 66) which included dietitians or nutritionists (n = 47), clients or patients, and their family or carer (n = 25), or nutrition and dietetic students (n = 11). Dietitians in the studies were working in private practice (n = 12), hospitals and outpatient clinics (n = 13) and community or public health services (n = 6). From the studies that articulated the health conditions of clients, most were described as managing chronic diseases (n = 14). A summary of included studies is provided in Table 1. Studies varied in their methodological quality ( Table 2). The number of studies that fulfilled all five design-specific criteria in the MMAT was 31 (of 76 eligible studies), with most being qualitative (n = 25). Five themes were identified across both analyses, which pertained to the primary terms ('relationship' and 'alliance') and associated terms (e.g., 'connection'). The themes showed that the therapeutic relationship: (i) is valued within clinical dietetic practice, (ii) involves complex and multifactorial interactions, (iii) is perceived as having a positive influence, (iv) requires skills training, and (v) is embedded in practice models and tools. The findings are described below by theme and whether they correspond to primary terms or associated terms.
The first theme reflected the finding that the therapeutic relationship appears important and valued by both parties as a component of the clinical dietetic consultation. This was mostly seen within qualitative findings; however, was also reported from quantitative and mixed methods findings. For example, Sladdin 84 Descriptors of the type of relationship valued by dietitians and clients included 'caring', 'genuine', 'positive', 'supportive' and 'ongoing'. However, a qualitative study described few clients perceiving that an 'ongoing' relationship would be useful in the context of type 2 diabetes management, based on the content and delivery of initial consultations attended. 7 Authors specified that this was the case for clients who were both satisfied and unsatisfied with their consultation; however, only specified a reason for those that were satisfied. Authors described these clients as perceiving that they had obtained the information they needed and did not perceive the need for an additional consultation. 7 Hence, the majority of data indicated that the client-dietitian relationship is valued but one study found clients with diabetes did not view an ongoing relationship as being of value.
The importance of the client and dietitian establishing a 'connection', 'rapport', 'partnership' and 'collaboration' was apparent, reflected through the descriptors 'essential', 'critical' and 'important'. One study that used qualitative interviews with dietitians about their weight management practice with children found that establishing rapport in initial interactions with paediatric clients was particularly important. 81 The second theme reflected the complex and multifaceted nature of the therapeutic relationship between clients and dietitians that was apparent from the identification of multiple factors and their influence on the relationship within numerous studies. This finding is typified by the description of the relationship as a 'complex interpersonal experience'. 48 The majority of factors appeared to be either attributes of the dietitian or client, techniques used by the dietitian or contextual factors (e.g., setting). Factors specific to either the dietitian or client are summarised in Table 3. Some examples include the dietitian being trustworthy and respectful, and the client's expectations of the consultation. Three contextual factors were identified; the type of care setting where the clientdietitian interaction occurs, the duration and frequency of interactions, and documentation requirements for the consultation. For example, two qualitative studies described long-term care (vs. acute care) and private practice settings as conducive to relationship development. 48,67 Factors were identified as influencing the 'rapport', 'connection', 'collaboration', 'partnership' and 'interaction', which were also specific to either the dietitian or client, or the context of their interaction (Table 4). Most factors were similar to those identified from the analysis of primary terms, however, some differed. For example, perceiving the dietitian as approachable and sensitive was thought to facilitate collaboration and rapport building. Contextual factors described were specific to developing a 'connection', 'rapport' and 'therapeutic interaction'. These included the amount of allocated time for the consultation as determined by the workplace (that is having more time facilitated rapport building) 36,43,64 and having a patient-centred physical environment where consultations occurred (e.g., 'neutralising hierarchy' by removing physical barriers such as a desk). 43 Qualitative studies that explored dietitians' perspectives identified that dietitians felt pressure from physicians to prioritise addressing clients' health rather than building rapport, and consequently spent less time focusing on rapport, 64 and that the private practice context was a 'motivator' to develop rapport with clients. 48 Reasons for this included maintaining their professional reputation and source of income. Another qualitative study that explored preferences of clients managing coeliac disease described clients preferring to engage with the same dietitian over repeated consultations. This was explained as assisting with rapport development. 73 The third theme indicated that a good therapeutic relationship appears to have a positive influence on clients and dietitians. Most findings were qualitative and taken from dietitians and clients' perspectives expressed through semi-structured interviews. For example, Morris et al. explored renal patients' perspectives of dietitians' communication styles and found that a 'good working relationship' facilitated patients 'feeling good' about themselves. 77 No studies were identified that analysed the statistical impact of the strength of the therapeutic relationship on tangible outcomes (such as improved diet quality scores) and as a result, the apparent positive influence of a good therapeutic relationship appears based on the perspectives of clients and dietitians only.
Findings pertaining to 'rapport', 'interaction', 'connection' and 'partnership' also mostly came from qualitative interview data. Perceptions of a positive influence on client's attendance and adherence to the treatment plan were described within several studies. For example, findings from a mixed methods study in an Indigenous Australian context described establishing a 'personal connection' as encouraging patients to attend their appointments. 42 Developing rapport was reported within qualitative studies as influencing clients' thoughts and feelings, specifically their trust and respect for the dietitian and confidence in engaging with the dietitian. 8,47 For example, results from a qualitative study that explored clients' and dietitians' perceptions of trust across multiple healthcare settings found that dietitians 'aimed' to build rapport to 'gain' the trust and respect of their client. 8 T A B L E 4 Summary of identified dietitian-related factors as facilitators or barriers to the rapport, collaboration, partnership and interaction between clients and dietitians Interaction Applying a person-centred approach Sending individualised text messages The fourth theme showed that therapeutic relationship development seems to be a valued component of training for dietitians, and should be a skill dietitians are trained in. This was identified across three areas: (1) the inclusion of relationship development skills in training programs, and findings describing (2) training adequacy and (3) the impact of training. Several studies described training programs for students and dietitians that focused on, or included components of relationship development. 53,58,65,80 One study described a training program designed to teach 'relationship-establishing skills' to nutrition students and thus appeared focused on the relationship itself. 65 In contrast, other studies listed the relationship as a component of training programs but often focused on different skill aspects of relationship development, such as counselling or communication skills. 53,58,80 Factors contributing to relationship development were articulated as part of these training programs and reflected those identified in the second theme (e.g., listening skills). 58 One study surveyed dietetic internship directors and reported that 73% thought students' preparation in developing a trusting relationship was adequate, while 19% indicated more training was needed (from a total sample of 66). 88 Results concerning the impact of dietitians' training on the relationship varied. In a quantitative survey, postregistration training was reported as contributing to improved relationships by 90% of dietitians surveyed. Unfortunately, details of the type of training were not elaborated upon. 94 Results from a mixed methods study suggested clients who engaged with dietitians trained in a particular program identified as being helpful in building relationships, felt 'more supported' than clients whose dietitian had not undertaken this training. 56 In addition, a non-randomised cross-sectional study reported findings that students trained in relationship-building skills displayed different verbal behaviours that were conducive to relationship development (e.g., responses that facilitated trust), compared to those students who were not trained. 62 These studies seemed to suggest a positive influence of training, but the aspects of the relationship that improved were often unclear. A secondary analysis of data from a stepped-wedge cluster-randomised controlled trial that evaluated the impact of motivational interviewing-based training on clients' and dietitians' ratings of therapeutic alliance found no evidence that motivational interviewingbased training supported improvements in therapeutic alliance. 78 The value of dietitians' training was also evident with regard to building 'rapport' and the 'therapeutic interaction'. A quantitative survey found dietitians felt adequately trained in rapport building in the context of eating disorder management. 32 In contrast, a qualitative study found dietitians working in public hospitals and private clinics in Israel did not feel adequately trained in managing 'emotional aspects' of the therapeutic interaction. 43 In addition, three quantitative studies presented data on nutrition students' rapport building skills after undergoing training. 39,52,65 Two studies found that students' skills in rapport building did not improve post training, 39,65 and one study reported that students' rated their rapport-building skills as more proficient than their assessors. 52 An Australian study found that competency standards had evolved to focus more on dietitians 'collaborating' and 'negotiating in partnership' with clients, further highlighting the need for dietitians to be trained in relationship building skills. 28 The fifth theme indicated that the therapeutic relationship was embedded to varying degrees throughout practice models and assessment tools for clinical practice. The development of a conceptual model and inventory for assessing patient-centred care was described by one quantitative study, which included establishing a genuine, caring and reciprocal therapeutic relationship. 86 A mixed methods study articulated 'relationship-building skills' as the first step in a process model for nutrition education and counselling. 34 Another mixed methods study described the development of the DIET-COMMS tool for assessing dietitians' communication skills with clients. 95 Unlike earlier models described, the therapeutic relationship was not the specific focus of the DIET-COMMS tool, nor was it an explicit component. Instead, the authors described the tool as a response to the relationship being at the core of the 'Nutrition and Dietetic Process', which may suggest the DIET-COMMS tool was developed to address some relationship development skills (i.e., communication skills specifically). 95 'Rapport', 'partnership' and 'collaboration' were embedded as components of assessment tools and practice models. 'Rapport' formed part of two different assessment tools, one that evaluated dietitians' interviewing skills 46 and another that evaluated their communication skills. 95 Rapport was also described as part of a nutrition-counselling model 52 and trialled within a scale that measured dietitians' confidence working with clients managing psychological conditions. 31 'Partnership' and 'collaboration' were identified as components of models for both communication and nutrition education in two different studies by the same authors. 11,34 4 | DISCUSSION This integrative literature review provides a comprehensive overview of the topic of the therapeutic relationship between clients and dietitians in the individual counselling context. It has done so by summarising existing research into qualitative themes. This review builds on previous knowledge gained from earlier research (including an integrative review on patient-centred care) 18 by including data that not only relates to explicit terms (such as 'relationship'), but also other terms with similar meanings (such as 'connection' and 'partnership'). Furthermore, this review builds on previous knowledge by including empirical research on students' training and studies published across all years. Hence, it adds to the evidence base by summarising literature that focuses more thoroughly on the phenomenon of the therapeutic relationship from all publication dates, including more recent evidence. In doing so, this comprehensive review has provided a footing for further work to be performed on this crucial aspect of clinical dietetic practice by identifying clear avenues for further research.
Major findings were that the therapeutic relationship appears to be a valued component of clinical dietetic practice and is perceived to have a positive influence on clients and dietitians. This was evident from mostly qualitative data describing dietitians' and clients' perspectives, and aligns with the philosophies of patient-centred, and relationship-centred healthcare paradigms. 99,100 These findings are consistent with other healthcare literature that also emphasise the importance of client-practitioner relationships, particularly with regard to improved health outcomes for clients. Within psychotherapy, a multilevel longitudinal meta-analysis by Flückiger et al. concluded that the therapeutic alliance, a recognised component of client-practitioner relationships, is a 'critical therapeutic element'. 101 Flückiger et al. confirmed robust findings from previous meta-analyses that have shown the therapeutic alliance accounts for approximately 7% of the variance in therapy outcomes across therapy types and study designs. 20,101-103 Although modest, Flückiger et al. describe this relationship between therapeutic alliance and therapy outcomes as greater than those of other treatment variables, such as the therapist's adherence to the treatment manual. 101 Hence, psychotherapy research has clearly identified and quantified the importance of the therapeutic alliance in relation to its positive impact on various treatment outcomes.
Interestingly, the current review did not identify any studies that quantitatively analysed the strength of the therapeutic relationship with tangible outcomes for clients in a dietetic context (such as diet quality scores). Unlike psychotherapy, this review has shown that the value of the therapeutic relationship and its positive influence on clients and dietitians appears to mostly come from qualitative data describing clients' and dietitians' perspectives. The extent of the research undertaken in psychotherapy highlights that substantial quantitative data that describes therapeutic relationship strength is lacking, and furthermore to what extent relationship strength accounts for client's therapeutic outcomes. Hence, there is a need for observational studies that assess the strength of these relationships in clinical dietetic practice from multiple perspectives (client, dietitian and observer) and their associations with client outcomes. For example, this could include investigating the correlation between client-rated relationship scores and their levels of motivation or self-efficacy. Quantitative data of this nature, that is alliance-outcome data, would assist the profession in better understanding how the therapeutic relationship may impact client's health outcomes and support existing qualitative descriptions of the relationship's positive influence.
A starting point for dietetics may be to focus on psychotherapist Bordin's 'working alliance' which captures several components of therapeutic alliance. 104 Key factors of the client-dietitian relationship identified in this review reflect Bordin's conceptualisation of the therapeutic alliance which articulates three components: (1) agreement on goals between therapist and client, (2) agreement on tasks to achieve the client's goals, and (3) their bond. 104 For example, this review has identified clients' unrealistic expectations of dietary change as a factor impacting relationship development, which can be interpreted as reflecting Bordin's 'Agreement on Goals'. 104 If a client has unrealistic expectations about the extent to which they can change their diet, it may be more difficult for the dietitian and client to agree on the client's goals. According to Bordin, this would impact the extent to which they can develop a strong alliance. 104 The current review has identified several relationship factors that are consistent with Bordin's conceptualisation of the therapeutic relationship. Of course, additional research is needed since the nature and importance of therapeutic relationships for health outcomes may be different in a dietetics context compared to a clinical psychology or psychotherapy context. Measures to assess the therapeutic alliance (e.g., Working Alliance Inventory) 105 have been used in one dietetics context already and other allied health disciplines. 78,106 The 'Working Alliance Inventory' has been adapted for use in other disciplines, such as physiotherapy. 102,105,107,108 This tool consists of 32 items, such as 'the client and therapist feel they trust one another. 105 Additional research is needed to assess the validity and reliability of this tool in dietetics, but it appears a feasible measure for the profession to begin to collect alliance-outcome data. This tool may also be useful for clinical dietitians to use within clinical supervision sessions to guide critical reflective practice and assist dietitians in articulating nuanced components of relationship development they feel they are doing well or could improve.
Findings from this review also provide some guidance as to what client outcome measures may be helpful to examine. Establishing a good 'relationship, 'connection' or 'rapport' were identified from primarily qualitative data as being important for treatment adherence, attendance and gaining the client's trust and respect. Thus, the relationship between therapeutic alliance and attendance and/or treatment adherence may be useful outcomes. Client engagement, how they felt about themselves and their ability to self-manage their diet were also identified in the review.
Studies from other allied health disciplines have applied the Working Alliance Inventory 105 to assess the impact of the therapeutic alliance on client outcomes. For example, Sønsterud et al. evaluated whether the therapeutic alliance between clients and speech therapists correlated with clients' motivation as part of stutter therapy. 109 A systematic review by Hall et al. also identified multiple studies that assessed whether the therapeutic alliance is related to client outcomes in a physiotherapy context. Hall et al. identified studies that also examined treatment adherence and satisfaction as outcomes. 108 The findings reported here and those from other allied health disciplines suggest that clients' attendance, as well as selfefficacy and motivation, might be useful outcome measures to begin to examine to support existing qualitative data in dietetics. Longitudinal designs would be useful in assessing how relationship quality may change over a treatment period and therefore how this may impact longer-term health outcomes.
There are strengths and limitations of this integrative literature review. The therapeutic relationship is a challenging, 'broad and complex' construct. 13 In order to capture this complexity, a comprehensive review was achieved by applying a systematic and healthcare-specific method. 12 In doing so, a number of search terms that reflected the therapeutic relationship (other than 'relationship' itself) were included. Several sources were searched, resulting in 76 included studies that were conducted in a variety of countries and employed different study designs. Despite this, grey literature was not searched and therefore some data concerning the therapeutic relationship is likely to have been missed. It is also plausible that despite every effort to ensure a comprehensive search strategy, some applicable studies may not have been retrieved.
To conclude, empirical literature recognises and discusses the therapeutic relationship between a client and dietitian to an extent, both explicitly and through other similar terms. A variety of studies support a good therapeutic relationship as a valued and multifactorial component of clinical dietetic practice that is perceived to positively influence the client and dietitian. There are limited descriptions of how the relationship exists in everyday clinical practice and the extent to which relationship strength might contribute to clients' health outcomes. Data describing how dietitians are trained and assessed in relationship-development skills and the impact of this training is also limited. Observational studies are needed to assess the extent to which the therapeutic relationship might be associated with health outcomes specific to dietetic interventions, and further support the data identified in this review.