Risk assessment of using off-label morphine sulfate in a population-based retrospective cohort of opioid-dependent patients

Abstract

Aims: Several addictovigilance studies have described the off-label use of morphine sulfate (MS) for nonchronic pain in opioid use disorder (OUD) patients as an alternative to conventional opioid substitution treatments (OSTs). This study primarily sought to compare the incidence of unintentional opioid-related overdose in the year following the prescription initiation in off-label MS users, compared to OST-maintained patients. Methods: Sequential cohorts of OUD patients who were regularly dispensed MS, buprenorphine, or methadone, between 1 April 2012 and 31 December 2014, were retrospectively identified using the French nationwide healthcare data system. The incidence of overdoses, deaths, doctor shopping, and complications of a viral, bacterial or thrombotic nature, was compared using the Cox regression method. Results: Overall, 1075, 20 834 and 9778 OUD patients without chronic-pain were included in the MS, buprenorphine, and methadone cohorts, respectively. Overdose incidence was 3.8 (P