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Table 1 Study characteristics

From: Medication adherence influencing factors—an (updated) overview of systematic reviews

Study Search period Inclusion criteria (patients and medication marked in italics)
Explorative systematic reviews
Aziz 2016 Not limited to February 2015 Patients with chronic conditions and different payment schemes
Human adults
Published in English
Evaluation of the effect of medication cost or method of payment on medication adherence
Clear description of study population and methodological approach
Only studies without a adherence intervention
Only randomized controlled trials, cross-sectional, longitudinal and observational/prospective or retrospective cohort studies
Only original research (review articles, thesis, commentaries, editorial letters, and case studies were excluded)
Broekmans 2008 Not limited to December 2006 Adult patients with chronic non-malignant pain
Adult patients with prescribed pain medication
Original research
Chen 2015 January 1990 to September 2013 Patients after acute coronary syndrome getting secondary prevention pharmacotherapy
Humans aged ≥ 18 years
Subjects hospitalized for an acute coronary syndrome
Prescription of at least one specified evidence-based medication after hospital discharge (beta-blocker, lipid-lowering agents, antiplatelet agents, ACEIs or ARBS)
Report of medication usage after hospital discharge
Measuring medication adherence and reporting its method of measurement
Only secondary adherence/non-adherence (not initiation)
At least 2 months follow-up
Specific follow-up time for calculating medication adherence
Calculation of medication adherence of patients with at least one filled prescription for the medication of interest during the follow-up time
All study designs
Only original research
Only analysis of the original study population
Publication in a peer-reviewed journal
Daley 2012 Not limited to January 2012 Patients with Parkinson
All ranges and duration of anti-parkinsonian treatments
All age ranges
Published in English
Presenting quantitative/qualitative data
Gourzoulidis 2017 Not limited to NR Patients with diabetes mellitus or heart failure
Different study types including retrospective, longitudinal observational cohort or cross-sectional studies (no reviews, meta-analyses, editorials, comments or letters to the editor)
Co-payment-interventions (introduction of co-payments or increases/decreases in existing co-payments)
Studies assessing the impact of co-payments on adherence
Exclusion of other types of cost-sharing, co-insurance, deductibles or caps
Exclusion of economic evaluations and treatment interventions
Only English and full-text published articles
Jaam 2017 Not limited to May 2016 Adults patients (≥ 18 years old) with diabetes mellitus type 1 or 2 living in the Middle East and North African region
Only original research reporting qualitative or quantitative data
Studies investigating factors associated with medication adherence
Patients receiving anti-diabetic medication
Krueger 2015 Not limited to March 2014 Adult patients with chronic heart failure
Studies analysing the relationship between age and medication adherence
Studies relating to pharmacological adherence
Only original research
Poor quality studies were excluded
Published in every language
Maimaris 2013 Not limited to May 2013 Adult population (general or on hypertension treatment)
Studies reporting on effects of national or regional (not individual or organisational levels) health system level arrangements (interventions, policies, or programs) on hypertension control
Adult population, including general population, population on treatment and population with specific comorbidities
Quantitative studies
Quantitative studies must report a measure of association between health system arrangement and at least one hypertension outcome of interest
Different study types including controlled trials, cohort studies and cross-sectional studies
Published in every language
Mann 2014 Not limited to March 2013 Adult patients with cardiovascular-related chronic conditions (coronary artery disease, hypertension, diabetes, hypercholesterolemia, cerebrovascular disease)
Studies assessing drug insurance (intervention) against a comparator group (including various cost-sharing strategies like co-payments, fixed co-payments, co-insurance, deductibles, caps, coverage gaps)
Different study designs including randomized controlled trials, non-randomized controlled trials, before-after-studies, interrupted time series
Studies reporting on medication adherence, clinical outcomes, quality of life, health care utilization or costs
Studies not focussing on health policy, value-based insurance or reference based pricing
English published
Mathes 2014(a) Not limited to December 2012 Hepatitis C-infected patients
Adult patients with hepatitis C
Patients getting medication regimes containing ribavirin
Every study type with quantitative measure of patient implementation adherence
Studies analysing potential adherence influencing factor/s
Studies conducted in WHO-mortality Stratum A (very low child mortality and low adult mortality)
Published in English or German
Mathes 2014(b) Not limited to December 2012 Patients taking oral anticancer agents
Patients ≥ 18 years old with malignant neoplasms
Patients taking oral anticancer agents
Studies analysing potential adherence influencing factor/s
Every study type with quantitative patient adherence measure (no interventional trials)
Studies not exclusively referring to intentional non-adherence measures
Published in English or German
Oosterom-Calo 2013 Not limited to August 2010 ≥ 50% heart failure patients
Quantitative results were reported
Studies of at least fair quality
Evaluations of interventions were not the main purpose
No descriptive study
No review paper
Published in English
Pasma 2013 Not limited to February 2011 Inflammatory arthritis patients
Used a reproducible definition or validated instrument to measure adherence
Provided a statistical measure to reflect the strength of the association between the determinant and adherence
 No letters, editorials, reviews, RCTs, case reports, qualitative studies and opinion articles
Verbrugghe 2012 NR Oral anti-cancer drugs
Age ≥ 18
Strong or moderate methodological quality
Written in English, French, German or Dutch
Original research articles published between 1990 and April 2012
Studies not conducted in developing countries
All study designs
Focused systematic reviews
Alsabbagh 2014 Not limited to February 2012 Patients taking antihypertensive drugs
Analysis of the influence of socioeconomic status on adherence to antihypertensive medications
All study designs
Published in English or French
Studies used electronic prescription database as source for nonadherence information
Multivariable modelling
Crawshaw 2016 January 2000 to December 2014 Adult patients (>  18 years old) after acute coronary syndrome (myocardial infarction and/or unstable angina) getting secondary prevention pharmacotherapy
Cross-sectional, retrospective cohort or prospective cohort studies
Measure of adherence to cardiac medication (antiplatelet agents, ACE inhibitors, ARBs, beta-blockers, lipid-lowering agents, calcium channel blockers or diuretics)
Standardised measurement of psychosocial variable
Assessment of strength of association between psychosocial factors and adherence
Published in English
Ghidei 2013 NR to July 2012 Older HIV-infected individuals
Only studies with control group
All study designs excluding case reports
Only studies with specified cut-off for adherence (≥ 80%)
Only studies not focussing on psychiatric disorders
Patient in the older classification aged > 45 years
Initial use of antiretroviral therapy at or after 1996
Participations actually on antiretroviral therapy
Participations without substance abuse
Peer-reviewed articles
Only original research
Hiko 2012 January 1997 to December 2011 Adults living with HIV/AIDS
Adult patients (aged ≥18 years) living with HIV/AIDS
Patients receiving antiretroviral therapy
Patients living in developed and developing countries
Studies identifying determinants of non-compliance regarding antiretroviral therapy (socioeconomic-related, health service-related, psychosocial- and behavioural-related and clinical-related outcome measures)
Quantitative evidence from observational analytic epidemiological studies (including prospective and retrospective cohort studies, case-control and comparative cross-sectional studies)
Published in English
Lewey 2013 NR to 04/2010 Patients receiving statin therapy
Studies evaluating adherence to statin therapy and reporting gender, race or ethnicity as a predictor of adherence
Studies using univariable or multivariable analysis
Studies reporting quantitative measures of adherence
Only original data
Studies reporting adherence to statin therapy and another medication were also included
Nachega 2015 January 1980 to September 2014 Patients receiving antiretroviral therapy
Every study design
Patients living with HIV
Patients receiving antiretroviral therapy
Studies assessing treatment adherence via objective or self-reporting measures
Studies considering employment as a possible adherence influencing factor
Sinnott 2013 1946 to September 2012 Participants received healthcare from a public insurance scheme
Comparator group was the same population/similar population who either did not pay co-payments or experienced no increase in co-payment
The intervention was co-payment; either an increase in an existing co-payment or the introduction of a co-payment (no other types of cost-sharing, for example, co-insurance)
Studies included were randomised controlled trials, controlled before and after studies, interrupted time series designs, repeated measures designs, and cohort designs
  1. NR Not Reported