Changes in drug-use behaviors among people who use drugs with comorbid psychiatric disorders across the COVID-19 pandemic: a three-phase longitudinal cohort study

Abstract

Introduction The COVID-19 pandemic substantially affected people who use drugs (PWUD) with comorbid psychiatric disorders. Lockdowns, shifts in drug markets, and fear of infection may have altered drug-use patterns. This prospective study examined changes in drug-use behaviors among PWUD with comorbid psychiatric disorders and identified factors associated with these changes across three distinct phases of the COVID-19 pandemic. Methods A cohort of adult PWUD with ICD-10-defined comorbid psychiatric disorders was followed longitudinally from March 2021 to January 2024. Drug-use behaviors were assessed at three time points: during the active COVID-19 pandemic period, after receipt of at least two doses of a World Health Organization (WHO)-endorsed COVID-19 vaccine, and after the WHO declared the end of the global pandemic. Structured interviews and standardized rating scales were used to assess demographic characteristics, ICD-10 comorbid psychiatric disorders, drug-use behaviors, DSM-5 substance use disorder severity, and psychological dependence. COVID-19 infection history and vaccination status were verified through centralized electronic health records. Within-person changes in drug-use behaviors across time points and factors associated with these changes were examined using mixed-effects models. Results One hundred and thirty participants (mean age 40.03 years) completed the study. The majority (62.3%) had a comorbid substance-induced psychotic disorder. Overall, 27.7% had laboratory-confirmed COVID-19 infection during the study period. Across the three phases, participants demonstrated significant reductions in substance use disorder severity and drug-use frequency. Sharing of drug-use equipment also declined and remained lower after the pandemic. Greater worry about contracting COVID-19 was associated with increased avoidance of drug use with others and reduced sharing of drug-use equipment. Prior COVID-19 infection was associated with lower drug-use frequency. Among individual drugs, cough syrup was uniquely linked to more frequent use, less solitary use, and sustained reductions in equipment sharing. Conclusion Adult PWUD with comorbid psychiatric disorders demonstrated sustained improvements in drug-use behaviors throughout the COVID-19 pandemic and after its official conclusion. Both prior COVID-19 infection and greater worry about contracting COVID-19 were associated with these positive behavioral changes.