Buprenorphine vs methadone substitution to retain patients in treatment

Methadone maintenance therapy was found to be statistically more effective than Buprenorphine maintenance therapy in a systematic review (Mattick et al., 2014) in:

• improving retention in treatment
  • in flexible doses studies (RR 0.83, 95 % CI 0.72 to 0.95, 5 studies, N=788);
  • in low doses studies (MMT ≤ 40mg BUP 2-6mg) (RR 0.67, 95 % CI 0.52 to 0.87, 3 studies, N=253);
• no difference was observed in reduction of opioid use as measured by urinalysis (SMD -0.11; 95 % CI -0.23 to 0.02, 8 studies, N=1027) or self-reported (SMD -0.11; 95 % CI -0.28 to 0.07, 4 studies, N=501)

However, at medium doses (MMT 40-85mg, BUP 7-15mg) and high doses (MMT ≥ 16mg, BUP ≥ 85mg) no difference was found between Methadone and Buprenorphine treatment in:

• improving retention in treatment
  • medium doses (RR 0.87, 95 % CI 0.69 to 1.10, 7 studies, N=780)
  • high doses (RR 0.79, 95 % CI 0. 02 to 3.16, 1 study, N=134)
• reducing opioid use as measured by urinalysis or self-reported

A new systematic review with network meta-analysis (Lim et al., 2022, 79 RCTs) confirmed the results and found a significant overall effect of Methadone in:

• retaining people in treatment (RR 2.62, 95 % CI 2.09 to 3.33) compared to control 
• in the network analysis Methadone was the highest ranked intervention (Surface Under the Cumulative Ranking [SUCRA] = 0.901) with control being the lowest (SUCRA = 0.000). Methadone was superior to buprenorphine for treatment retention (RR = 1.22; 95% CI = 1.06-1.40) yet buprenorphine superior to naltrexone (RR = 1.39; 95% CI = 1.10-1.80).

In a more recent systematic review with meta-analysis (Degenhardt et al., 2023, 32 RCTs), the primary outcomes considered were retention in treatment, treatment adherence, and extra-medical opioid use; the following results were concluded:

• For retention beyond one month, methadone had higher retention rates compared to buprenorphine (RR 0.76, 95% CI 0.67–0.85; I²=74.2%; 16 studies, N=3151)
• For extra-medical opioid use, there is some evidence indicating lower rates of buprenorphine compared to methadone as measured by urinalysis (–0.20, 95% CI –0.29 to –0.11; I²=0.0%; 3 studies, N=841)

To summarise, the authors highlight that while methadone may have better treatment retention rates, there are few differences in other comparative outcomes. Therefore, it is important to consider other factors and take a client-centered approach when prescribing.