Barriers to Prescription Medication Adherence Among Homeless and Vulnerably Housed Adults in Three Canadian Cities

Objectives: Medication adherence is an important determinant of successful medical treatment. Marginalized populations, such as homeless and vulnerably housed individuals, may face substantial barriers to medication adherence. This study aimed to determine the prevalence of, reasons for, and factors associated with medication nonadherence among homeless and vulnerably housed individuals. Additionally, we examined the association between medication nonadherence and subsequent emergency department utilization during a 1-year follow-up period. Methods: Data were collected as part of the Health and Housing in Transition study, a prospective cohort study tracking the health and housing status of 595 homeless and 596 vulnerably housed individuals in 3 Canadian cities. Logistic regression was used to identify factors associated with medication nonadherence, as well as the association between medication nonadherence at baseline and subsequent emergency department utilization. Results: Among 716 participants who had been prescribed a medication, 189 (26%) reported nonadherence. Being >= 40 years old was associated with decreased likelihood of nonadherence (adjusted odds ratio [AOR] = 0.59; 95% confidence interval [CI] = 0.41-0.84), as was having a primary care provider (AOR = 0.49; 95% CI = 0.34-0.71). Having a positive screen on the AUDIT (Alcohol Use Disorders Identification Test; an indication of harmful or hazardous drinking) was associated with increased likelihood of nonadherence (AOR = 1.86; 95% CI = 1.31-2.63). Common reasons for nonadherence included side effects, cost, and lack of access to a physician. Selfreported nonadherence at baseline was significantly associated with frequent emergency department use (>= 3 visits) over the follow-up period at the bivariate level (OR = 1.55; 95% CI = 1.02-2.35) but was not significant in a multivariate model (AOR = 1.49; 95% CI = 0.96-2.32). Conclusion: Homeless and vulnerably housed individuals face significant barriers to medication adherence. Health care providers serving this population should be particularly attentive to nonadherence among younger patients and those with harmful or hazardous drinking patterns.