Di Prete, Bethany, et al. Matching Study Design to Prescribing Intention: The Prevalent New User Design In Opioid Research. 2021. https://doi.org/10.17615/4cbq-t195
Di Prete, B., Oh, G., Moga, D., Dasgupta, N., Slavova, S., Slade, E., Delcher, C., Pence, B., & Ranapurwala, S. (2021). Matching Study Design to Prescribing Intention: The Prevalent New User Design in Opioid Research. https://doi.org/10.17615/4cbq-t195
Di Prete, Bethany, G Yeon Oh, Daniela Moga, Nabarun Dasgupta, Svetla Slavova, Emily Slade, Chris Delcher et al. 2021. Matching Study Design to Prescribing Intention: The Prevalent New User Design In Opioid Research. https://doi.org/10.17615/4cbq-t195
Affiliation: Gillings School of Global Public Health
Affiliation: Injury Prevention Research Center
Background: In drug studies, research designs requiring no prior exposure to certain drug classes may restrict research on important populations. For example, currently marketed abuse-deterrent formulation (ADF) opioids are routinely used in patients with prior prescription opioid exposure. The traditional new user design excludes patients with prior exposure to prescription opioids, hence incident ADF users are not representative of the overall ADF user population. A prevalent new user design, wherein patients are prescribed similar treatments (or potential comparators) before starting the new treatment, likely better represents the intended ADF patient population.
Objectives: To evaluate the appropriateness of new user versus prevalent new user design for estimating post-market effectiveness of ADFs and examine patterns of ADF initiation.
Methods: We used pharmaceutical claims data from a large private insurer in North Carolina [USA] from 2009-2018. Included patients were new ADF users age 18-64 with 6 months of continuous enrollment prior to their first ADF claim. Incident users were identified as those with no prescription opioid claims in a 6-month washout period prior to ADF initiation. Prevalent new users were identified as those with non-ADF opioid claims during the 6 months before ADF initiation, so long as they also had a 6-month washout period of no opioid claims prior to first non-ADF opioid claim. We compared sample sizes by study design and described ADF utilization patterns.
Results: We identified 8,841 eligible patients who initiated an ADF. Of these, 2,332 (26%) were classified as incident users, whereas 6,509 (74%) were prevalent new users and would be excluded in a traditional new user design. Most incident ADF users started with both an ADF and an immediate-release (IR) opioid concurrently (85%). Among prevalent new users, common ADF initiation patterns were: adding an ADF to an IR opioid regimen (43%), an immediate switch from IR opioids to an ADF (15%), and a delayed switch from IR opioids to an ADF (14%).
Conclusions: Three-quarters of patients initiating ADFs had prior prescription opioid use and would be excluded in a traditional new user study design. A prevalent new user design would increase sample size and better capture clinically meaningful patients. These findings may apply to studies of other medications where prior exposure is a labeled prerequisite, such as higher dose ER opioids and second-line therapies. Future work will explore prevalent new user designs and consider nuances in ADF initiation such as immediate versus delayed switching by incorporating time-matching to address opioid tolerance.