Background: Although individuals dependent only on alcohol and those dependent on both alcohol and drugs typically are not studied together in clinical trials, they are treated together in most treatment programs. In this study we compared epidemiological characteristics of the alcohol-only and alcohol-and-drug dependents in a treatment sample to assess differential treatment needs.
Method: Patients admitted to treatment at a health maintenance organization's chemical dependency program were sampled and interviewed by using a structured questionnaire. The sample included 491 alcohol-only and 217 alcohol-and-drug dependents. Demographic characteristics, lifetime and current substance use, Addiction Severity Index composite scores, and DSM-IV criteria for alcohol and drug dependence were assessed at admission.
Results: The odds of alcohol-and-drug dependence were higher among males, African Americans (when compared with whites), those who were younger, and those with less than college education. The risk was also higher among those who initiated heavy drinking or drug use before the age of 18. Increased psychiatric and family/social problems also were associated with combined dependence.
Conclusions: Even in this relatively homogeneous socioeconomic status population, demographic characteristics were important predictors of type of dependence. Treatment programs which provide services that address prevention and psychosocial problems should pay attention to age of initiation as well as psychiatric and social problems.