Abstract
BackgroundCost-related nonadherence to medications (CRNA) is common in many countries and thought to be associated with adverse outcomes. The characteristics of CRNA in Canada, with its patchwork coverage of increasingly expensive medications, are unclear.ObjectivesOur objective in this systematic review was to summarize the literature evaluating CRNA in Canada in three domains: prevalence, predictors, and effect on clinical outcomes.MethodsWe searched MEDLINE, Embase, Google Scholar, and the Cochrane Library from 1992 to December 2019 using search terms covering medication adherence, costs, and Canada. Eligible studies, without restriction on design, had to have original data on at least one of the three domains specifically for Canadian participants. Articles were identified and reviewed in duplicate. Risk of bias was assessed using design-specific tools.ResultsTwenty-six studies of varying quality (n = 483,065 Canadians) were eligible for inclusion. Sixteen studies reported on the overall prevalence of CRNA, with population-based estimates ranging from 5.1 to 10.2%. Factors predicting CRNA included high out-of-pocket spending, low income or financial flexibility, lack of drug insurance, younger age, and poorer health. A single randomized trial of free essential medications with free delivery in Ontario improved adherence but did not find any change in clinical outcomes at 1 year.ConclusionCRNA affects many Canadians. The estimated percentage depends on the sampling frame, the main predictors tend to be financial, and its association with clinical outcomes in Canada remains unproven.
Highlights
Cost-related nonadherence to medications (CRNA) is common in many countries and thought to be associated with adverse outcomes
The estimated percentage depends on the sampling frame, the main predictors tend to be financial, and its association with clinical outcomes in Canada remains unproven
All studies reported only on adults, except two studies based on the Canadian Community Health Survey (CCHS) [40, 47] which included those at least 12 years of age
Summary
Cost-related nonadherence to medications (CRNA) is common in many countries and thought to be associated with adverse outcomes. Other studies have suggested that higher medication adherence is associated with better outcomes and lower healthcare costs across many disease states and populations, including children [17,18,19]. All of these studies are susceptible to confounding due to their lower-quality design and the “healthy user effect”—the likelihood that adherent individuals have other unmeasured healthy behaviors [17]. The landmark MI-FREEE trial showed that randomization to full coverage of key cardiac medications for patients postmyocardial infarction improved adherence but made no difference in the primary outcome of vascular events [20]
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