Background: Medication nonadherence is common and is associated with adverse outcomes. Alcohol misuse may be a risk factor for nonadherence; however, evidence is limited.
Objective: To identify whether alcohol misuse, as identified by a simple screening tool, is associated in a dose-response manner with increased risk for medication nonadherence in veterans attending primary care clinics.
Design: Secondary analysis of cohort data collected prospectively from 1997 to 2000 as part of a randomized, controlled trial.
Setting: 7 Veterans Affairs primary care clinics.
Participants: 5473 patients taking a statin, 3468 patients taking oral hypoglycemic agents, and 13 729 patients taking antihypertensive medications.
Measurements: Patients completed the Alcohol Use Disorder Identification Test-Consumption (AUDIT-C) questionnaire, a validated 3-question alcohol misuse screening test. Their scores were categorized into nondrinkers; low-level alcohol use; and mild, moderate, and severe alcohol misuse. Medication adherence, defined as having medications available for at least 80% of the observation days, was measured from pharmacy records for either 90 days or 1 year after the alcohol screening date. Logistic regression was used to estimate the predicted proportions of adherent patients in each AUDIT-C group and adjusted for demographic and clinical covariates.
Results: The proportion of patients treated for hypertension and hyperlipidemia who were nonadherent increased with higher AUDIT-C scores. For 1-year adherence to statins, the percentage of adherent patients was lower in the 2 highest alcohol misuse groups (adjusted percentage of adherent patients, 58% [95% CI, 52% to 65%] and 55% [CI, 47% to 63%]) than in the nondrinker group (66% [CI, 64% to 68%]). For 1-year adherence to antihypertensive regimens, the percentage of adherent patients was lower in the 3 highest alcohol misuse groups (adjusted percentage of adherent patients, 61% [CI, 58% to 64%]; 60% [CI, 56% to 63%]; and 56% [CI, 52% to 60%]) than in the nondrinker group (64% [CI, 63% to 65%]). No statistically significant differences were observed for oral hypoglycemics in adjusted analyses.
Limitation: This observational study cannot address whether changes in drinking lead to changes in adherence and may not be generalizable to other populations.
Conclusion: Alcohol misuse, as measured by a brief screening questionnaire, was associated with increased risk for medication nonadherence.