A temporal and dose-response association between alcohol consumption and medication adherence among veterans in care

Background: Previous studies have shown that alcohol consumption is associated with decreased medication adherence, but this association may be confounded by characteristics common among those who drink heavily and those who fail to adhere (e.g., illicit drug use). Our objective was to determine whether there are temporal and dose-response relationships between alcohol consumption and poor adherence. Methods: We administered telephone interview surveys to participants in the Veterans Aging Cohort Study, an eight-site observational study of HIV+ and matched HIV- veterans in care, to determine whether alcohol consumption on a particular day was associated with nonadherence to prescribed medications on that same day. We used the Time Line Follow Back to measure alcohol consumption and the Time Line Follow Back Modified for Adherence to measure adherence. Individuals were categorized as abstainers (no alcohol in past 30 days), nonbinge drinkers (alcohol in past 30 days but <= four standard drinks on each day), or binge drinkers ( <= five standard drinks on at least one day). Results: Among 2702 respondents, 1582 (56.6%) were abstainers, 931 (34.5%) were nonbinge drinkers, and 239 (8.9%) were binge drinkers. Abstainers missed medication doses on 2.4% of surveyed days. Nonbinge drinkers missed doses on 3.5% of drinking days, 3.1% of postdrinking days, and 2.1% of nondrinking days (p < 0.001 for trend), and this trend was more pronounced among HIV+ individuals than HIV- individuals. Binge drinkers missed doses on 11.0% of drinking days, 7.0% of postdrinking days, and 4.1% of nondrinking days (p < 0.001 for trend), and this trend was comparably strong for HIV+ and HIV- individuals. Conclusions: Among veterans in care, self-reported alcohol consumption demonstrates a temporal and doseresponse relationship to poor adherence. HIV+ individuals may be particularly sensitive to alcohol consumption.