Method:
We analysed SF-6D health utility data collected alongside the CTN-0027 randomized controlled trial. The trial spanned 24 weeks, and was designed to assess the changes in liver
enzymes related to treatment with buprenorphine/naloxone (BUP/NX) and methadone (MET) in
participants entering opioid agonist treatment for opioid dependence. Health states were defined as follows: pre-treatment, on treatment (BUP/NX or MET) and post-treatment. A linear mixed effects regression model was specified to determine utility weights for these health states, controlling for age, gender, histories of liver abnormality and mental health comorbidity, ongoing opioid and stimulant use (indicated by positive urine drug screens) and observed severe adverse events (SAEs).
Result: The study sample consisted of 1261 clients and 3038 measurements (pre-treatment:N=1171; BUP/NX:N=810; MET:N=819;post-treatment:N=238; median duration post-treatment: 3.2 weeks (interquartile range: 1.1,16.0)). Participants were of mean age= 37.8 (SD: 11.2), 32.3% were female, and 87.3% had comorbid mental health conditions at baseline assessment. Mean health utility for the complete sample was 0.67 (SD: 0.11) at baseline. Female gender, liver abnormality, other opioid use and SAEs were each independently associated with individual health utility. Health utility improvement was observed among both BUP/NX (mean effect: 0.033(p<0.01) and MET clients (0.046(p<0.01)) compared to baseline assessment, however this improvement was not sustained following treatment discontinuation (0.012(p=0.11). Health utility gain was greater among MET clients compared to BUP/NX clients (0.014 (p=0.02)).
Conclusion: The health utility benefits of OST were found to be transient and likely to revert back to pre-OST initiation levels following study discontinuation. A small but statistically significantly higher health utility gain was observed among individuals randomized to receive methadone versus buprenorphine.