Lessons and Challenges from a 6-Month Randomized Pilot Study of Daily Ethanol Consumption: Research Methodology and Study Design

Background: Observational studies and crossover feeding studies suggest that moderate alcohol use may benefit cardiovascular risk, but we know of no long-term randomized trials that have tested this hypothesis. Objective: We evaluated the feasibility of an efficacy study of daily ethanol use in a 6-mo randomized pilot study in adults at higher cardiovascular risk. Methods: In a double-blind, randomized, controlled parallel-design trial, we screened 67 adults aged ≥55 y and randomly assigned 45 participants to consume 150 mL of an artificially sweetened beverage with or without 10% grain alcohol daily for 6 mo. Participants were asked to consume no other alcohol and returned monthly to receive the beverage and undergo measurement of HDL cholesterol, liver function tests, and complete blood counts. Results: Of the 45 randomly assigned participants, 39 completed the trial; the primary reason cited for attrition was inconvenience. None of the participants reported problem drinking or developed any serious adverse events or abnormal biochemical findings. However, we observed no differences in concentrations of HDL cholesterol, HDL lipoprotein subclasses, aspartate aminotransferase, alanine aminotransferase, γ-glutamyltransferase, mean corpuscular volume, or adiponectin between the alcohol and control arms, suggesting that adherence was poor. Every participant accurately identified their assigned beverage, most with great certainty. Conclusions: In this parallel-design pilot study of daily alcohol use, we observed none of the expected changes in markers of alcohol intake, which suggests poor adherence to this pure alcohol intervention. Our results suggest that long-term trials of alcohol consumption, if they are conducted in light drinkers similar to these, must use pragmatic designs for maximal feasibility. This study was registered at clinicaltrials.gov as NCT01377727.