Incidence of high dosage buprenorphine and methadone shopping behavior in a retrospective cohort of opioid-maintained patients in France.

Abstract

Opioid Substitution Treatment (OST) misuse and diversion have significantly increased worldwide. Obtaining OST prescriptions from multiple prescribers, known as doctor shopping, is a way in which opioids may be diverted. The aim of this study was to assess the incidence of OST (high dosage buprenorphine (HDB) and methadone (MTD)) shopping behavior and identify associated risk factors, and its impact on mortality. A retrospective cohort of patients treated by OST between April 1, 2004 and December 31, 2012 from a sample of the French Health Insurance database was established. Doctor shopping was defined as ≥1 day of overlapping prescriptions written by ≥2 different prescribers and filled in ≥3 different pharmacies. A total of 2043 patients were enrolled, 1450HDB and 593 MTD. The one-year incidence of shopping behavior was 8.4% (95% CI: 7.0-10.1) in HDB group and 0% in MTD group, compared to 0.2% (95% CI: 0.1-0.2) for diuretics. On multivariate analysis, factors associated with HDB shopping behavior were: male gender HR: 1.74 (95% CI: 1.20-2.54); low-income status HR: 2.95 (95% CI: 2.07-4.44); mental health disorders HR: 1.43 (95% CI: 1.06-1.94); concurrent hypnotics use HR: 1.90 (95% CI: 1.39-2.61); concurrent use of weak opioids HR: 1.48 (95% CI: 1.09-1.99) and morphine HR: 1.69 (95% CI: 1.02-2.80). HDB shoppers had a higher, yet non-significant risk of death (HR: 1.56 (95% CI: 0.64-3.81)) than non HDB shoppers. Shopping behavior was only found in high dosage buprenorphine patients and concerned almost one out ten patients.