Trajectories of opioid consumption as predictors of patient-reported outcomes among individuals attending multidisciplinary pain treatment clinics.

Abstract

This study aimed to identify opioid consumption trajectories among persons living with chronic pain (CP) and put them in relation to patient-reported outcomes 6 months after initiating multidisciplinary pain treatment. This study used data from the Quebec Pain Registry (2008-2014) linked to longitudinal Quebec health insurance databases. We included adults diagnosed with CP and covered by the Quebec public prescription drug insurance plan. The daily cumulative opioid doses in the first 6 months after initiating multidisciplinary pain treatment were transformed into morphine milligram equivalents. An individual-centered approach involving principal factor and cluster analyses applied to longitudinal statistical indicators of opioid use was conducted to classify trajectories. Multivariate regression models were applied to evaluate the associations between trajectory group membership and outcomes at 6-month follow-up (pain intensity, pain interference, depression, and physical and mental health-related quality of life). We identified three trajectories of opioid consumption: "no or very low and stable" opioid consumption (n = 2067, 96.3%), "increasing" opioid consumption (n = 40, 1.9%), and "decreasing" opioid consumption (n = 39, 1.8%). Patients in the "no or very low and stable" trajectory were less likely to be current smokers, experience polypharmacy, use opioids or benzodiazepine preceding their first visit, or experience pain interference at treatment initiation. Patients in the "increasing" opioid consumption group had significantly greater depression scores at 6-month compared to patients in the "no or very low and stable" trajectory group. Opioid consumption trajectories do not seem to be important determinants of most PROs 6 months after initiating multidisciplinary pain treatment.