Background: People with substance use disorders (SUD) and co-occurring chronic pain report the use of myriad substances, which is concerning due to the heightened risk of overdose associated with polysubstance use. Identifying malleable factors associated with polysubstance use in this population can inform interventions. In this study, we examined whether two pain processes - pain interference and pain catastrophizing - were associated with polysubstance use. Objectives: We examined the cross-sectional associations among self-reported pain interference and catastrophizing and polysubstance use. We also determined if sex and primary SUD moderated these associations. Methods: Participants were 236 (36% female) adults receiving inpatient treatment for SUD (58% alcohol use disorder, 42% opioid use disorder) who met criteria for chronic pain. We utilized negative binomial regression to examine associations between pain interference and catastrophizing (focal independent variables) and the number of substances used in the month before treatment (i.e., polysubstance use; outcome). Results: Participants used three substances, on average, in the month prior to treatment. Neither pain interference (IRR = 1.05, p = .06) nor pain catastrophizing (IRR = 1.00, p = .37) were associated with polysubstance use. The association between pain interference and polysubstance use was moderated by sex and primary SUD (ps<0.01), such that these variables were positively related in men and those with alcohol use disorder. Conclusion: Pain interference and catastrophizing were not uniformly associated with polysubstance use, underscoring the need to examine other factors associated with polysubstance use in this population. However, men and those with alcohol use disorder might benefit from interventions targeting pain interference to reduce polysubstance use.
Keywords: Chronic pain; alcohol use disorder; opioid use disorder; pain catastrophizing; pain interference; polysubstance use; sex.