Co-occurring amphetamine use and associated medical and psychiatric comorbidity among opioid-dependent adults: results from the Clinical Trials Network

Daniel J Pilowsky1, Li-Tzy Wu2, Bruce Burchett2, Dan G Blazer2, George E Woody3, Walter Ling41Departments of Epidemiology and Psychiatry, Columbia University, and the New York State Psychiatric Institute, New York City, NY; 2Department of Psychiatry and Behavioral Sciences, School of Medicine, Duke University Medical Center, Durham, NC; 3Department of Psychiatry, School of Medicine, University of Pennsylvania and Treatment Research Institute, Philadelphia, PA; 4David Geffen School of Medicine, NPI/Integrated Substance Abuse Programs, University of California, Los Angeles, CA, USABackground: In response to the rising rate of treatment admissions related to illicit use of amphetamines (eg, methamphetamine), we examined the prevalence of amphetamine use among treatment-seeking, opioid-dependent adults, explored whether amphetamine users were as likely as nonamphetamine users to enroll in opioid-dependence treatment trials, and determined whether amphetamine users manifested greater levels of medical and psychiatric comorbidity than nonusers.Methods: The sample included 1257 opioid-dependent adults screened for participation in threemultisite studies of the National Drug Abuse Treatment Clinical Trials Network (CTN001-003), which studied the effectiveness of buprenorphine for opioid detoxification under varying treatment conditions. Patients were recruited from 23 addiction treatment programs across the US. Medical and psychiatric comorbidity were examined by past-month amphetamine use (current vs former) and route of administration. Five mutually exclusive groups were examined, ie, nonusers, current amphetamine injectors, current amphetamine noninjectors, former amphetamine injectors, and former amphetamine noninjectors.Results: Of the sample (n = 1257), 22.3% had a history of regular amphetamine use. Of the 280 amphetamine users, 30.3% reported injection as their primary route. Amphetamine users were more likely than nonusers to be white and use more substances. Amphetamine users were as likely as nonusers to enroll in treatment trials. Bivariate analyses indicated elevated rates of psychiatric problems (depression, anxiety, hallucinations, cognitive impairment, violence, suicidal thoughts/attempts) and medical illnesses (dermatological, hepatic, cardiovascular, respiratory, neurological, seizure, allergy conditions) among amphetamine users. After adjusting for demographic variables and lifetime use of other substances: current amphetamine users and former injectors showed an increased likelihood of having medical illnesses and hospitalizations; current i