Predictors of Long-Term Opioid Effectiveness in Patients With Chronic Non-Cancer Pain Attending Multidisciplinary Pain Treatment Clinics: A Quebec Pain Registry Study

Objective This study aimed to identify characteristics of individuals who are most likely to benefit from long-term opioid therapy in terms of reduction in pain severity and improved mental health-related quality of life (mQoL) without considering potential risks. Methods This was a retrospective cohort study of 116 patients (age = 51.3 +/- 12.5 years, male = 42.2%) enrolled in the Quebec Pain Registry between 2008 and 2011 and who initiated opioid therapy after their first appointment in a multidisciplinary pain clinic and persisted with this treatment for at least 12 months. Clinically significant improvement was defined as a 2-point decrease on the PEG (pain, enjoyment of life, and general activity) Scale of pain severity (scored from 0 to 10) at 12-month follow-up and a 10-point increase on the Short-Form-12 Health Survey version 2 (SF12-v2) Mental Health-Related Quality of Life Summary Scale, which corresponds to 1 standard deviation (SD) of the mean in the general population (mean = 50, SD = 10). Results Clinically significant reduction in pain severity was observed in 26.7% of patients, while improvement in mQoL was reported by 20.2% of patients on long-term opioid therapy. Older age (odds ratio [OR] = 1.04; 95% confidence interval [CI]: 1.0 to 1.08;P = 0.032) and alcohol or drug problems (OR = 0.26; 95% CI: 0.07 to 0.96;P = 0.044) were weakly associated with pain severity at 12-month follow-up. Baseline higher pain severity (OR = 0.62; 95% CI: 0.43 to 0.91;P = 0.014) and baseline higher mQoL (OR = 0.89; 95% CI: 0.83 to 0.95;P = 0.001) were associated with non-improvement in mQoL. Conclusion The analysis failed to identify clinically meaningful predictors of opioid therapy effectiveness, making it difficult to inform clinicians about which patients with chronic non-cancer pain are most likely to benefit from long-term opioid therapy.