Table 1.

Review Characteristics

First Author (Year)	Aim(s)	Type of Review	Search Period	Search Strategy	Inclusion Criteria		Number of Included Studies	Design of Studies	Quality Assessment Tool	Funding/Disclosures
Banerjee (2016)24	To identify health system features, programs or strategies which act as barriers or facilitators to adherence to evidence-supported medications for CVD secondary prevention.	Systematic review	From inception to October 2015	MEDLINE, Embase, Cochrane Library, PsychINFO, Health Systems Evidence, HMIC, LILACS, Africa-Wide Information and Google Scholar were searched. Conference proceedings and reference lists of relevant research articles were also searched. Searched terms were provided.	Quantitative and qualitative studies reporting associations of local, national, regional or international health system level factors, interventions, policies or programs with adherence to medications for the secondary prevention of CVD. Included studies had analyses of barriers and facilitators to adherence or persistence to at least one of β blockers, statins, angiotensin–renin system blockers and aspirin.		25	11 RCTs, 1 non-randomized trial, 11 cohort studies, 1 cross-sectional, 1 case-control.	The Cochrane Risk of Bias tool	Funding was World Heart Federation Emerging Leaders Programme. The authors declared that no competing interests exist.
Chee (2014)21	To determine patients’ perceptions of statins, as well as the impact these had on statin use and adherence.	Literature review	October 1991 to May 2012	PubMed, Medscape, the Cochrane Database and the Western Pacific Region Index Medicus were searched. Search terms were provided. Additional studies were identified using a manual reference search for included citations.	Studies that reported factors affecting adherence or interventions that target to improve adherence.		58	Unspecified	Unspecified	Unspecified
Hope (2019)17	To identify predictors of statin adherence for the primary prevention of CVD.	Systematic review	January 1984 to May 2017	Embase, MEDLINE, CINAHL and PsychINFO were searched. Search terms were provided.	Articles were included if they reported on: 1) people receiving treatment for the primary prevention of CVD, 2) statins were prescribed, 3) adherence was defined as the extent to which patients followed their statins regimen during the period of prescription, 4) predictors of adherence were defined and measured, and 5) if the study was original research.		19	3 cross-sectional studies, 11 retrospective cohort studies, 3 prospective cohort studies, and 2 RCTs.	As reported by Sanderson4	The authors received no specific funding for this work. The authors declared that no competing interests exist in relation to this systematic review. After review of the journal policy the authors of this manuscript have the following competing interests: Prof. George Kitas and Prof. Deborah Symmons.
Ju (2018)25	To provide a comprehensive synthesis of qualitative studies on patient perspectives on statins for CVD prevention.	Systematic review	From inception to October 2016	The ENREQ framework was followed. MEDLINE, Embase, PsycINFO, and CINAHL were searched. Google Scholar and reference lists of relevant studies and reviews were also searched. PhD dissertations were searched on ProQuest Dissertations and Theses database, British Library Electronic Digital Thesis Online Service, and the Europe E-theses Portal. It is unclear whether search terms were provided.	Qualitative studies that reported patients’ perspectives on statins were included. Studies involving adult patients at risk of CVD and patients receiving statins as primary or secondary preventive therapy for CVD were eligible. Articles that only included patients with familial hypercholesterolemia or perspectives from health professionals were excluded.		32	19 qualitative studies, 6 mixed methods studies, 1 ethnomethodologic study, 2 phenomenological studies, and 2 ethnographic studies. The 2 last studies were unspecified.	Not applicable	This work was supported by a National Health and Medical Research Council Partnership Grant (NHMRC) (1092674), including support from the National Heart Foundation of Australia, and an NHMRC Program Grant (1092597). Two authors are supported by NHMRC Fellowships (1106716 and 1042717). The funders had no role in the study design; in the collection, analysis, and interpretation of data; in the writing of the report; and in the decision to submit the article for publication.
Lemstra (2012)22	To quantify the proportion of adherence to statin medications by study design, and to provide estimates of risk indicators associated with nonadherence to statin medications.	Meta-analysis	From inception to June 2011	PubMed, PsycINFO, CINAHL, Cochrane CENTRAL, DARE, NHSEED, HTA Database, and Embase were searched. Search terms were provided. Reference sections of each article were reviewed for additional papers.	Articles were included if they: 1) determined the proportion of adherence to statin therapy during a defined period, 2) were observational cohort studies or RCTs, and 3) used a validated tool for measurement of adherence. Articles were restricted to English language. The review excluded studies with fewer than 50 participants.		67	53 cohorts and 14 RCTs.	The Delphi list for RCTs. As reported by Sanderson4 for observational studies.	One author was funded by an unconditional research grant from the Ministry of Health in the Province of Saskatchewan which obtained an unconditional research grant from Merck Frosst/Schering Pharmaceuticals. Another author had educational financial support from the Province of Saskatchewan’s Ministry of Health, AstraZeneca Canada, Merck Frosst/Schering, and Pfizer Canada. Two authors had no conflicts of interest to disclose. None of the sponsors were involved in developing this study or writing the article.
Lewey (2013)18	To evaluate the effect of race/ethnicity and gender on adherence to statin therapy for primary or secondary prevention.	Systematic review and meta-analysis	From inception to April 2010	MEDLINE, Embase, ClinicalTrials.gov, and the Cochrane Database of Systematic Reviews were searched. Search terms were provided.	Studies that evaluated adherence to statins and reported on gender, race, or ethnicity as a predictor of adherence in univariate or multivariable analysis. Studies were excluded if they did not: 1) present quantitative measures of adherence, 2) present original data, 3) evaluate gender, race, or ethnicity as a predictor of adherence, or 4) evaluate statin use.		53	47 cohort studies, 2 RCTs and 4 cross-sectional.	Newcastle Ottawa Quality Assessment Scale.	The authors received research support to study medication adherence through unrestricted grants from Aetna, CVS Caremark, the Robert Wood Johnson Foundation, and the Commonwealth Fund. The authors were solely responsible for the design and conduct of this study, all study analyses, the drafting and editing of the manuscript, and its final contents. One author is a consultant to Mercer Health and Benefits, Inc. Another author is a consultant on research methodology to United Healthcare. A third author is an employee of CVS Caremark.
Mann (2014)23	To determine the association between drug insurance and patient cost sharing strategies on medication adherence, clinical and economic outcomes in those with chronic diseases.	Literature review	From inception to March 2013	MEDLINE, Embase, CINAHL, Cochrane Central Register of Controlled Trials, and Current Controlled Trials were searched. Search terms were provided.	Included studies that examined various cost sharing strategies including co-payments, coinsurance, fixed co-payments, deductibles and maximum out-of-pocket expenditures.		11	2 separate reports of 1 RCT, 4 interrupted time series, and 5 controlled before-after studies.	The Cochrane Risk of Bias tool for RCTs, and the Cochrane EPOC taxonomy for non-randomized trials.	This study was funded by a team grant from Alberta Innovates – Health Solutions (AI-HS) to the Interdisciplinary Chronic Disease Collaboration. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. One author was supported by an AI-HS Clinician Fellowship award. Another author was supported by an AI-HS Trainee award. Two authors were supported by career salary support awards from AI-HS. Another author was supported by the Roy and Vi Baay Chair in Kidney Research. One author was supported by a Government of Canada Research Chair. Three authors were also supported by an alternative funding plan from the Government of Alberta and the Universities of Calgary and Alberta.
Mann (2010)20	To identify reliable predictors of non-adherence to statins.	Review of literature and meta-analysis	From inception to February 2009	MEDLINE, Cochrane Central Register of Controlled Trials, Database of Abstracts of Reviews of Effects, National Health Service Economic and Evaluation Database, Health Technology Assessment Database, Embase, PsycINFO. Searched terms were provided.	Articles were included if they (1) included prospective or retrospective observational cohorts in which statins were evaluated as an outcome measure, (2) included adults above 18 years, (3) used either a validated self-report scale or an objective measure with more than 50 participants, (4) had a description of the study design and the analysis reported on at least 2 predictors of adherence to statins in a multivariable analysis with relative risks. Studies with fewer than 50 participants were exclude. Articles were restricted to English language.		22	22 cohort studies.	Quality assessment applied, but not specified.	This research was supported by grant lK23DK081665, a Patient-Oriented Mentored Scientist Award through the National Institute of Diabetes, Digestive, and Kidney Diseases. The funder had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; and preparation, review, or approval of the manuscript. The authors have declared that no competing interests exist.
Ofori-Asenso (2018)19	To identify factors associated with non-adherence and discontinuation among older statin users (≥ 65 years)	Systematic review	From inception to December 2016	Followed PRISMA guidelines. MEDLINE, Embase, CINAHL, PsycINFO, NHSEED, DARE, and Cochrane Central Register of Controlled Trials were searched. Search terms provided.	Articles were eligible if they: 1) reported on predictors of nonadherence and/or discontinuation among older statin users, 2) adopted objective adherence measurements, 3) adopted validated scales (in case of utilized self-reports), 4) measured adherence via the medication possession ratio, proportion of days covered (PDC), or proportion of doses taken, only those employing an 80% cutoff to dichotomize adherence were considered. Articles were restricted to English language.		22	Unspecified	NIH Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies.	The first author was supported by a Monash Graduate Scholarship and Monash International Postgraduate Research Scholarship for his doctoral studies. One author was funded by a National Health and Medical Research Council Senior Research Fellowship. No other funding has been received to undertake the work. The last author reports past participation in advisory boards and/or receiving honoraria from: Amgen Australia; AstraZeneca/Bristol-Myers Squibb Australia; Janssen-Cilag; Merck, Sharp, and Dohme (Australia); Novartis Australia; Novo Nordisk; Sanofi; Servier Laboratories; Takeda Australia; and Monash University (undertaking contract work for AstraZeneca Pty Limited/Bristol- Myers Squibb Australia Pty Limited) for work unrelated to this study.