Objectives: Health related quality of life (HRQoL) has been increasingly considered an endpoint in evaluations of treatment for substance use disorders. We aimed to characterize longitudinal patterns of HRQoL in individuals with opioid use disorder (OUD) and with a history of opioid agonist treatment (OAT) with methadone.
Methods: The EuroQol EQ-5D, a preference-weighted measure of HRQoL, was assessed in individuals with OUD and with a history of OAT enrolled in three prospective cohort studies between December 2011 and May 2014, with a maximum of five biannual assessments. We used latent class growth analysis to identify HRQoL trajectory classes and their association with self-reported current OAT receipt. Class assignment was derived from posterior probabilities and we explored time-invariant and time-varying determinants of trajectory class membership.
Results: Our study included 443 individuals (median age 47, 37% female); 24.6% reported use of illicit opioids at every follow-up, 69.1% during at least one follow-up. We identified three latent HRQoL trajectory classes that were stable regardless of current OAT receipt: stably high (n=107, 24.2%), stably moderate (n=260, 58.7%) and stably low HRQoL (n=76, 17.2%). A history of either a physical disability or of a mental health illness increased the probability of membership assignment to a lower HRQoL class.
Conclusions: The non-significant association of OAT with HRQoL may suggest that the modest immediate HRQoL gains after OAT engagement, observed in short-term studies, may not persist over time. Implications for cost-effectiveness analysis and clinical practice are discussed.
Keywords: Health related quality of life; Longitudinal health utility; Opioid agonist treatment; Opioid use; Stimulant use; Treatment outcomes.
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