Historical and contextual variation in daily opioid consumption rates: implications for supply control, service delivery, and research.

Background: Illegal opioids can create substantial harms, but the extent depends on multiple factors, including the amount consumed.Objectives: To examine how consumption varies across time and context, with implications for treatment and drug policy.Methods: We searched EBSCOhost and PubMed for literature on individuals: (1) not-in-treatment and purchasing from illegal markets, (2) reporting pre-treatment use at treatment intake, and (3) with opioid use disorder (OUD) receiving medically supplied opioids. A total of 135 articles were deemed relevant.Results: Average consumption intensities vary enormously, from below 100 morphine milligram equivalents (MME) per day for use outside of treatment where prices are high, to ~600 MME in typical illegal markets, and 1,100-1,800 MME per day when supply is free, as in heroin assisted treatment and injectable hydromorphone treatment. MME in methadone programs (190-460) is less than in the traditional British heroin prescribing system (600-1,300). Intensities tended to be higher in recent times, whereas the prices have been lower. Studies during the fentanyl era suggest MMEs per day may be much higher than in the past.Conclusion: The adaptability of consumption has several potential implications. Expansions in supply could have greater effects on quantity consumed than on prevalence. Treatment protocols and overdose prevention strategies may need to adjust for higher baseline consumption. Furthermore, assumptions about health harms from long-term use may need revisiting if they are predicated on lower, historical consumption intensities. These findings are caveated by limitations in reporting of data and variations in methodologies. Hence, greater investments in monitoring consumption intensities are warranted.