People who abuse cigarettes, alcohol and/or heroin are less likely to drop out of a substance use disorder treatment than those who are addicted to cocaine, according to a new study led by a researcher at the University of Alabama at Birmingham.

The study, which was led by Sara Lappan, PhD, a former postdoctoral scholar in the UAB School of Public Health and a visiting instructor in the Department of Human Studies in the School of Education, found that approximately 30% of participants in psychosocial substance use disorder treatments do not finish the programs. Lappan examined data from studies that analyzed substance use disorder treatments from 1965 to 2016. This is the first time a study of this kind has been published.

"Dropout in treatment for substance dependence/abuse is a major issue that doesn't get the attention it deserves," Lappan said. "What we have done is quantified more than 50 years of clinical trial data and hopefully have brought more attention to this issue."

Previous studies have shown that dropping out of a treatment program is a major predictor of relapse. The goals of this study were to estimate average dropout rates of in-person psychosocial substance use disorder treatments and to assess predictors of dropouts with the goal of decreasing the overall rate in the future.

"Our hope is that future researchers will use our findings to investigate the more nuanced reasons contributing to dropout and create solutions to address and decrease its occurrence," Lappan explained. "For anyone conducting a feasibility study with a psychosocial treatment for substance use disorder, our research allows for them to know an average dropout rate to expect."

The researchers found that those who smoke more cigarettes per day or use a greater percentage of heroin were less likely to drop out than those who used cocaine, methamphetamines and/or other major stimulants.

"Major stimulants have been rated as having among the greatest dependence potential and impairment of mental functioning," Lappan explained. "Major stimulant use may also be associated with risky sexual behavior more so than other drug use, which suggests a particularly robust relationship with impulsive behavior. Also, there are no approved pharmacotherapies for major stimulant dependence, making withdrawal distress worse, which may make it more difficult to complete treatment."

Lappan adds that contingency management appears to be the most effective of behavioral interventions for major stimulant use, which she says suggests a strong need for competing incentives among users of major stimulants that may not be met by most psychosocial interventions.

The study, "Dropout rates of in-person psychosocial substance use disorder treatments: a systematic review and meta-analysis," was published Addiction, the official journal of the Society for the Study of Addiction.