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A SYSTEMATIC REVIEW OF HEPATITIS VIRUS REVIEW STUDIES: A CASE OF HEALTH ECONOMIC EVALUATION ANALYSIS

Objective: Systematic reviews of economic analysis are necessary for assessing reports and making a decision. A systematic review of systematic reviews is mean of summarizing the current evidence across specialties of the same or very similar intervention, to provide a synthesis treatment effect. The aim of this study was to explore and to assess the quality of systematic reviews conducted hepatitis economic evaluation. Methods: This study was designed as a systematic review following the AMSTAR guideline through Medline, Cochrane, and Science Direct databases. It was scoped in publication period of 2001 and 2016 in international journals. The quality assessment of the included studies was based on AMSTAR checklist. Two authors did the appreciation independently and all the different results were solved by discussion to give the conclusion. Results: 851 publications found, only 25 studies of those met the inclusion criteria. These studies consisted of 5 studies for vaccination and 20 for non-vaccination. There were only 16% (n=4) based on PRISMA guideline; and twenty-one studies (64%) were not showing about the method of the systematic review or not based on any guideline. Only three articles has published in 2016 with a high standard. Conclusion: According to the results of the appraisal AMSTAR checklist, this review shows clearly the current situation and an urgent need for an increase of quality of hepatitis virus review studies based on health economic evaluation. Original Article A SYSTEMATIC REVIEW OF HEPATITIS VIRUS REVIEW STUDIES: A CASE OF HEALTH ECONOMIC EVALUATION ANALYSIS PHUONG HONG LE, QUANG VINH TRAN, TRUNG QUANG VO Department of Pharmacy Administration, Faculty of Pharmacy, University of Medicine and Pharmacy, Ho Chi Minh City 700000, Vietnam Email: voquangtrungdk@gmail.com


INTRODUCTION
Economic evaluation in health care studies has been more considerable and become a useful method for economists to improve the efficiency of the solution offered [1]. Researchers have appreciated the importance of giving an overview of individual studies to have a better quality and wider scope. They have assessed quantity or quality, summed up data of a group of records in comparable areas. As an effect, several systematic reviews of economics have been published in many international journals and they have been an essential part of the public policymaking process [1]. A systematic review of systematic reviews is a mean of summarizing the current evidence across specialties of the same or similar intervention, to provide a synthesis treatment effect [2,3]. There are numerous reviews conducted, so it is difficult to access the information from these articles. A systematic review of reviews is a potential way to recap the details of the reviews. It permits readers to have a brief diverse ways such as comparison, contrast and provide clinical decision makers with the evidence they need [4].
Liver diseases have been regarded as a public health issue due to its effect on the patient body, finances of their family and society. Some kinds of them can be mentioned as hepatitis A virus (HAV) [5,6], hepatitis B virus (HBV) [7][8][9][10][11], hepatitis C virus (HCV) [12][13][14], hepatitis D virus (HDV) [15], hepatitis E virus (HEV) [16,17], and liver cirrhosis [18]. Thanks to vaccination, people can be prevented from these physical problems and that could lead to reducing a number of infection cases. Presenting the relationship between cost of illness, cost-effectiveness, and stages of liver diseases are the reason why researchers carry out economic evaluation studies of hepatitis virus [19].
Participants of each research could be different, namely, the authors focused on an aspect of hepatitis. From the information of their articles, the readers could be able to appraise the efficacy of diagnoses, treatment methods or pharmaceutical products. To give more reliable evidence, many hepatitis economic evaluation reviews were published with various topics included in HAV [20], HBV [21], HCV [22], comparing between HBV and HCV [23,24], other liver diseases [25,26], hepatitis vaccinations [28][29][30]. Of hepatitis economic evaluation, none of the authors designed their studies as a literature review of studies, and there is relatively small number of reviews of published economic evaluation reviews in other subjects at present, for examples, about vaccination [31], hormone therapy, chemotherapy, and targeted therapy for breast cancer [32], telemedicine [33]. The aim of this study was to explore general characteristics of a systematic review of hepatitis virus and its vaccination in health care economic evaluation.

Study design
This study was conducted as a systematic review of economic evaluation reviews about liver diseases in several countries from 2001 to 2016. Two reviewers did the search so that reviews of hepatitis-virus-related economic evaluation were found. After that, filtering was carried out following pre-identified inclusion and exclusion criteria. The assessment was handled based on the piloted form that we had designed before to collect all the information that we needed and "A measurement tool to assess systematic reviews" tool (AMSTAR) to check the quality of each review. We recapped the results and had a discussion to give conclusions which help the future researchers will have a better standard review.

Literature search
This study was searched on Medline, Cochrane, and Science Direct databases to find articles published from 2001 to 2016 independently, then combined and discarded duplicates. The seeking target was to access to published or accepted review publications about the economic evaluation of hepatitis virus. The keywords, "hepatitis [MeSH terms]" and "economic evaluation [MeSH terms]" and "review [MeSH terms]" and "immunization [MeSH Terms]", were searched in "Title/Abstract" so as to limit a number of search results.

Fig. 1: Flow of information
Publications were chosen if they were literature or systematic reviews of economic evaluation articles which used primary data, with topics such as hepatitis virus, hepatitis virus vaccine or liver diseases. Studies were excluded due to being published in other languages, but not English or not relating to humanity. Conference abstracts or textbooks should be eliminated. When screening had finished, there were 25 publications retrieved ( fig. 1).

Data assessment
More than 24 instruments were used for the quality evaluation of systematic reviews [34,35] such as The Quality of Reporting of Meta-analyses (QUOROM) [34], Overview Quality Assessment Questionnaire (OQAQ) [34], a checklist designed by Sack [36], by Oxman and Guyatt [37], by Beverley J Shea [35], Preferred Reporting Items of Systematic reviews and Meta-analyses (PRISMA) [38] or Critical Appraisal Skills Programme (CASP) of systematic reviews [39] etc. In this study, AMSTAR tool was to have a summary of reviews of hepatitis virus economic evaluation. AMSTAR is a trustful method for documenting the standard of systematic reviews [40]. For appraising the quality of reviews in this studies, we discussed to give the conditions that the reviews should meet for each question in AMSTAR checklist. To understand the meaning of the AMSTAR question [35] clearly and how to score a review, we consulted correlative reports [35,[41][42][43].
Factors of the checklist focused on the estimation of databases authors used, inclusion and exclusion criteria, the quality of the included studies, publication bias and conflict of interest. In each AMSTAR question, there were four options such as 'yes' (question fulfilled), 'no' (question not performed), 'can't answer' (not enough information to answer the question) or 'not applicable' (question not met adequate conditions to tick 'yes'). If 'yes' category was chosen, item got '1 point'; if not, it had '0 points' [41].
Twenty-five publications were appraised with AMSTAR checklist by two authors independently and differences were solved based on persuasion to give the final decision. According to Mohammad O Sharif 's recommendation [41], 25 publications were divided into three following groups depending on its total points such as low quality (0-3), medium quality (4-7), and high quality (8)(9)(10)(11).
Moreover, a table was created to collect the information concerned, for instance, the number of articles which concentrated on the vaccine, type of economic evaluation, the usage of some databases frequency and checklists.
There were only 16% (n=4) [12,23,24,44] based on PRISMA guideline. On the contrary, twenty-one studies (64%) did not showing about the method of the systematic review or not based on any guideline. The number of publications reviewed in each included study fluctuated. Almost publications (72%) chose 2 to 20 articles in order to have an overview. There were six studies that analyzed more than 20 publications. Especially, the quantity of Crossan et al., 2015's review/article [46] was observable with extremely high fig. (302 papers reviewed) due to its extensive topics comprised of HBV, HCV, alcoholic liver disease (ALD), and non-alcoholic fatty liver disease (NAFLD) while the others mentioned one topic (table 1).
Most of the authors declared that they used the only keyword (40%) or did not mention the progress of searching (44%). Very few reviewers used MeSH terms [51] or both MeSH terms and keywords in the seeking [25,27,48]. Among twenty-two studies whose authors normally claimed which databases they used (except three reviews [26,50,55] were not available), 80% (n=20) selected Medline while LILACS or Health STAR was taken by two studies. The number of articles using EmBase ranked the second place with 14 studies (56%) and frequency of Cochrane, NHSEED, and HTA chosen was with six, five, and four times respectively.
Moreover, Studies also made use of some different databases, for instance, EconLit, CINAHL, NICE, WOPEC, SciELO, Web of Science, DARE, Social Sciences Citation Index, Science Citation Index Expanded etc. More than a half of studies (52%) used from one to five databases while there were three articles [47,53,54] whose authors did the search in 11-20 databases. The highest number of databases was twenty [53], but the authors did not list databases. On the contrary, the smallest was one [25] (table 1)

DISCUSSION
Although there were not various systematic reviews of economic assessment reviews, most of them used AMSTAR checklist to appraise the standard of eligible publications. It proved that AMSTAR was a reliable instrument [40]. In general, none of the 25 articles we assessed got full of 11 AMSTAR scores due to a number of publications that did not meet the requirement to have full points in some questions. One-hundred percent of included articles did not evaluate publication bias clearly (item 10), and four studies used the methods to combine the findings of studies appropriately (item 9) (table 4). Before evaluating the quality of eligible studies by AMSTAR, two authors deliberated about various conditions for choosing "yes" in some items, such as in item 3, if the articles satisfied 4 in 5 factors below • There were at least two sources should be searched.
• The report should express the period of time concerned.
• The report should include database used.
• Keyword/MESH terms must be stated.
• Searching should be supplemented by consulting current contents, reviews, textbooks, specialized registers, or experts in the particular field of study, and by reviewing the references in the studies found.
Almost studies met the first, the second and the third condition above (84-88%).
For item 4, assessment result was "yes" if the author should state whether or not they excluded any reports based on language and publication.
In item 6, characteristics of the eligible studied must provide 4 in 6 items comprising of participants, interventions, comparisons, outcomes, study design, the other ranges of characteristics for example age, race, sex, relevant socioeconomic data, disease status, duration, severity, or other diseases. This study had some limitations such as the number of databases that we searched was much smaller than other systematic reviews of economic evaluation reviews as we stated. Moreover, our eligible criteria were the reviews published in English and conducted about liver-diseases-related economic evaluation, but we focused on HAV, HBV, HCV, and liver fibrosis whilst there are various liver diseases. There were also other reviews of hepatitis virus economic evaluation that our searching strategy could not find. In addition, it was possible that there were some mistakes in the results of studies.

CONCLUSION
At present, reviews of economic evaluation in the health care sector become better about not only quantity but also quality and they play an important role in supporting studies the improvement of the effectiveness of hepatitis virus diagnosis, treatment, and vaccination. According to our results, there is a lack of research about HCV immunization, combining hepatitis virus vaccinations, and that could be great topics for future reviewers. Moreover, we emphasize the importance of search strategy, the number of included journals, and usage of checklists for the reliability of results.

ACKNOWLEDGEMENT
The authors express their gratitude to all staffs at Professional Healthcare Management, Education and Research center (ProHES) and Assoc. Prof. Pham Dinh Luyen at Faculty of Pharmacy, University of Pharmacy and Medicine, Ho Chi Minh City for their supporting.

AUTHOR CONTRIBUTION
Phuong Hong Le, Quang Vinh Tran and Trung Quang Vo designed a methodology and conducted the search strategy. All three authors collected and appreciated the data. After that, Phuong Hong Le summarized and analyzed the outcome. Phuong Hong Le, Quang Vinh Tran and Trung Quang Vo wrote this paper and reviewed overall to concur with the final manuscript.