Daily patterns of opioid and stimulant use and associated risk-behavior outcomes: A cohort study

People who use opioid and stimulant drugs have high overdose rates. Little is known about day-to-day variation in patterns of use of these drugs and their association with other drug use behaviors.

Participants with past-two-week opioid or stimulant use completed daily cellphone surveys over a two-week period. We classified each day's opioid-stimulant combination into five mutually exclusive groups. We estimated associations of each group with prevalence of 7 same-day outcomes -alcohol, cigarette, THC, and tranquilizer use, injecting drugs, using xylazine, and using drugs alone - using random-intercept linear regression.

87 participants (38% female, 54% ≥ 55 years old) completed 868 daily surveys. The day-level prevalences of each opioid-stimulant combination were: 21% with opioids and stimulants used at least once at the same time; 13% with both drugs used but never at the same time; 28% with opioid use only; 8% with stimulant use only; and 31% with neither drug used. Within-person day-to-day variation was common. As compared to days when participants used opioids and stimulants at the same time, when participants used opioids only, they were significantly less likely to use cigarettes (within-person prevalence difference [wPD] -0.09, 95% CI -0.17 to -0.01), tranquilizers (wPD -0.08, 95% CI -0.12 to -0.05), or injection drugs (wPD -0.22, 95% CI -0.28 to -0.15).

Within-person day-to-day changes in opioid-stimulant combinations were common. Use of opioids only was associated with lower prevalence of risky behaviors as compared to use with stimulants. Co-occurring stimulant use is a potentially modifiable target for harm reduction.