RWE-002 - CONCURRENT GABAPENTIN AND OPIOID USE AND RISK OF MORTALITY IN MEDICARE RECIPIENTS WITH NON-CANCER PAIN.

M. Corriere, A. Dickson, L. Daniel, P. Nepal, K. Hall, W. Plummer, W. Dupont, K. Murray, M. Stein, W. Ray, C. Chung; Vanderbilt University Medical Center, Nashville, TN, USA.

Background: Gabapentin is prescribed frequently for pain management and generally is perceived as safe. However, gabapentin can cause respiratory depression, exacerbated by concomitant central nervous system depressants (e.g., opioids), a concern for vulnerable populations. We compared mortality rates among gabapentin and duloxetine users with or without concurrent opioids in a 20% Medicare sample.

Methods: We conducted a retrospective cohort study, new user design, in Medicare enrollees ages 65-89 without severe illness who filled prescriptions between 2015-2018 for gabapentin (n=232,686) or duloxetine (n=33,997) with non-cancer chronic pain. Daily opioid doses, estimated in morphine milligram equivalents (MME), were classified into none, low (0< MME < 50), and high (≥50 MME), per CDC recommendation. The outcomes were all-cause mortality (primary) and out-of-hospital mortality (secondary). We used inverse probability of treatment weighting to adjust for differences between gabapentin and duloxetine users.

Results: During 117,236 person-years of follow-up, 1,396 patients died. All-cause mortality rate in gabapentin users was 12.16/1,000 person-years versus 9.94/1,000 in duloxetine users (adjusted hazard ratio [aHR]=1.08, 95%CI: 0.88-1.34). Rates were similar for users with no concurrent opioids (aHR=1.01, 95%CI: 0.79-1.29) or low-dose daily opioids (aHR=1.08, 95%CI: 0.67-1.76). Gabapentin users on high-dose daily opioids had an increased rate of mortality versus duloxetine users on high-dose opioids (aHR=2.25, 95%CI: 1.26-4.00). Out-of-hospital mortality yielded similar results.

Conclusion: In this retrospective cohort of seniors, concurrent use of high-dose opioids and gabapentin was associated with a higher mortality risk than that for concurrent use of high-dose opioids and duloxetine.