Matching study design to prescribing intention: The prevalent new‐user design for studying abuse‐deterrent formulations of opioids.

Purpose: In drug studies, research designs requiring no prior exposure to certain drug classes may restrict important populations. Since abuse‐deterrent formulations (ADF) of opioids are routinely prescribed after other opioids, choice of study design, identification of appropriate comparators, and addressing confounding by "indication" are important considerations in ADF post‐marketing studies. Methods: In a retrospective cohort study using claims data (2006–2018) from a North Carolina private insurer [NC claims] and Merative MarketScan [MarketScan], we identified patients (18–64 years old) initiating ADF or non‐ADF extended‐release/long‐acting (ER/LA) opioids. We compared patient characteristics and described opioid treatment history between treatment groups, classifying patients as traditional (no opioid claims during prior six‐month washout period) or prevalent new users. Results: We identified 8415 (NC claims) and 147 978 (MarketScan) ADF, and 10 114 (NC claims) and 232 028 (MarketScan) non‐ADF ER/LA opioid initiators. Most had prior opioid exposure (ranging 64%–74%), and key clinical differences included higher prevalence of recent acute or chronic pain and surgery among patients initiating ADFs compared to non‐ADF ER/LA initiators. Concurrent immediate‐release opioid prescriptions at initiation were more common in prevalent new users than traditional new users. Conclusions: Careful consideration of the study design, comparator choice, and confounding by "indication" is crucial when examining ADF opioid use‐related outcomes. [ABSTRACT FROM AUTHOR]