Polysubstance use patterns among individuals applying for opioid-use disorder treatment in the U.S.

The prevalence of polysubstance use is known to be high among individuals who use/misuse drugs. This study aims to extend existing research by (a) measuring polysubstance use through objective drug testing rather than fallible self-reports, (b) determining the most frequent three- and four-substance combinations instead of being limited to typical two-substance combinations, and (c) examining a comprehensive panel of substances beyond those commonly studied. Participants were a convenience sample of individuals applying for methadone maintenance treatment in 11 clinics across 7 states (n= 1098, 43.2% female). Participants voluntarily provided oral fluid and urine specimens to the study during clinic intake that were tested for 22 types of substances by liquid chromatography/tandem mass spectrometry (LC-MS-MS). Polysubstance use was high (89.6%), with the mean number of substances used by participants = 3.3, up to a maximum of 11. There were ten three-substance combinations with prevalences of 5% or greater, the most frequent being opiates, fentanyl and cocaine (10.5%). There were nine four-substance combinations with prevalences of 2% or greater, the most frequent being opiates, fentanyl, cocaine and cannabis (4.5%). Many of these combinations can produce serious and even life-threatening interactions and side effects. The combination with perhaps the most severe potential consequence of concurrent use is the combination of opiates, fentanyl, and tramadol (5.1%), which all have sedative or central nervous system (CNS) depressive effects. Clinicians should consider that symptoms of substance use are likely due to diverse combinations of substances, not only problematic use of a single presenting "substance of choice."