Background: Alcohol and other drug use disorders co-occur with cigarette smoking and negatively impact cessation outcomes.
Objectives: This study examined the differential effects of current and lifetime DSM-IV drug diagnoses on the 6-month smoking outcomes of 84 untreated heavy drinking smokers who were motivated to quit smoking in the next 6-months.
Methods: Generalized estimating equations (GEE) assessed changes in nicotine dependence, readiness to quit smoking, and prevalence of heavy smoking from baseline to 6-months as a function of time, baseline drinking severity, and drug diagnosis.
Results: GEE models showed that nicotine dependence and prevalence of heavy smoking decreased over 6-months, irrespective of drug diagnosis and baseline alcohol consumption. Several 3-way interactions were found, showing differences in the rate of change over time in readiness to quit smoking and prevalence of heavy smoking as a function of current versus lifetime drug diagnosis and higher versus lower of baseline alcohol consumption. Conclusions/Importance: Drug diagnoses are common in risky drinking smokers, and significantly impede changes in smoking behavior and motivation to quit. Treatment planning for smoking cessation should include a thorough assessment of current and past drug use behavior to determine the impact on readiness to quit and quit success. Mechanisms of change in smokers with multiple substance use diagnoses should be examined.
Keywords: Substance use disorders; alcohol; behavior change; cigarettes; drug diagnosis; nicotine dependence.