Health related quality of life trajectories of patients in opioid substitution treatment

Background: While opioid substitution treatment (OST) provides the opportunity for substantial improvements in health related quality of life (HRQoL), this relationship is seldom documented and poorly understood. Our objectives were to identify differences in trajectories of HRQoL among chronic opioid-dependent patients and factors associated with improvement and deterioration in HRQoL following enrolment in opioid substitution treatment.

Methods: In the North American Opiate Medication Initiative (NAOMI) randomized controlled trial, the Euroqol (EQ-5D) and other measures of demographic, health and drug use characteristics were collected at baseline and quarterly follow-up. Latent class growth analysis was applied to identify classes of HRQoL trajectories during treatment, while baseline correlates of class membership and factors associated with changes in HRQoL were identified in multivariate analyses.

Results: Three classes of individual HRQoL growth trajectories were identified: class 1: low and constant (19.5%), class 2: moderate and improved (61.2%), and class 3: high and constant (19.3%). Class 1 members were younger and more likely to be female, while class 3 members were less likely to have chronic conditions and had lower illicit drug use severity at baseline. Changes in HRQoL were associated with improvements in housing status (positive), medical events (negative) and decreases in illicit drug use (positive).

Conclusions: Insight into the extent of HRQoL response and characteristics of patients responding to treatment can be used to design interventions that maximize HRQoL improvement. Given its role in economic evaluation and subsequent resource allocation decisions, HRQoL should be considered an endpoint in treatment evaluations for opioid dependence.