Predictors of clinical trial dropout in individuals with co-occurring bipolar disorder and alcohol dependence

Individuals with co-occurring bipolar disorder and alcohol dependence have particularly low rates of retention in clinical trials. Past research has identified a variety of factors associated with dropout in this population, but few have been replicated. The present study investigated the ability of several baseline variables to predict clinical trial dropout in a sample of individuals with co-morbid bipolar and alcohol use disorders.

Demographics, psychiatric diagnoses, recent alcohol use, mood pathology, and risk taking behavior (measured with the Balloon Analogue Risk Task) were evaluated as predictors of dropout from a randomized clinical trial of acamprosate for individuals with co-morbid bipolar and alcohol use disorders (n=30) using stepwise logistic regression.

Risk taking behavior was the only significant predictor of dropout in the present study (OR=1.44, p=0.03); opiate dependence marginally predicted dropout as well (OR=13.46, p=0.08). A model consisting of these predictors, as well as acamprosate group status (p=0.13), provided excellent prediction of dropout (i.e., area under the ROC curve=0.94; R(2)=0.53).

Given the robust relationship between risk taking and dropout in the present study, the Balloon Analogue Risk Task may represent a valuable tool for researchers to predict who will drop out of clinical trials for comorbid bipolar and substance use disorders.