Patterns of illegal drug use among an adult alcohol dependent population: Results from the National Survey on Drug Use and Health

The use of illegal drugs is common in alcohol dependence and significant psychological and social consequences are associated with the concurrent use of alcohol and illegal drugs. However, little literature has examined the patterns of concurrent-drug use in alcohol dependent individuals. A latent class analysis (LCA) was used to determine whether patterns of past year illegal drug use existed in a national sample of 6059 alcohol dependent respondents of the combined 2005, 2006 and 2007 National Survey on Drug Use and Health. Multinomial logistic regression was then used to determine whether demographic variables, mental health disturbance and social consequences were predictive of drug use classes. Results of the LCA demonstrated a 5-class solution with optimal fit deduced by Bayesian Information Criterion minima. The five classes included: a close to zero probability of illegal drug use (class 1: 65%), medium marijuana, medium sedatives/tranquilizers and high analgesics (class 2: 7%), high marijuana, medium cocaine use (class 3: 21%), high probabilities of marijuana, cocaine, sedatives and analgesic use (class 4: 6%) and a high concurrent-drug use except other hallucinogens (class 5: 1%). Regression results suggest that younger age, comorbidity, engaging in deviant behaviors, sexually transmitted infection and incarceration are associated with concurrent illegal drug use in alcohol dependent individuals. Findings advocate that more intense psychiatric and drug dependence treatment resources may be needed for concurrent-drug using alcohol dependent populations and provide evidence for targeted prevention and treatment interventions.