Buprenorphine is safer during induction than methadone and, despite shorter retention in treatment, is not associated with a higher risk of death, a study from New South Wales has found.

The authors compared the relative benefits and risks of buprenorphine and methadone as treatment options for the management of heroin dependence, following almost 6,000 patients as they entered treatment in an Australian clinic setting. A total of 3,349 patients (56%) received buprenorphine and 2,643 methadone.

The study found a high dropout rate at the start of treatment, with 24% of buprenorphine and 7% of methadone patients leaving treatment within the first week. Methadone patients stayed in treatment longer than buprenorphine patients, median duration of treatment 271 days for methadone, and 40 days for buprenorphine.

Buprenorphine patients had significantly lower mortality during induction, 1.5 deaths/10,000 inductions compared with 13.4 deaths/10,000 methadone inductions (RR = 0.114, 95% CI 0.002-0.938).

Maintenance treatment was associated with a low death rate for both treatments and there was no statistically significant difference between them, 2.9 deaths/1,000 person treatment years for buprenorphine and 3.5 deaths/1,000 person treatment years for methadone (RR = 0.81, 95% CI 0.31-1.96, p = 0.64).

The difference in overall mortality was not clinically significant, 3.0/1,000 person treatment years for buprenorphine and 4.5/1,000 person treatment years for methadone (RR = 0.65, 95% CI 0.27-1.45, p=0.28).

Despite the greater frequency of entering and leaving buprenorphine treatment, and more time spent out of treatment following buprenorphine, the overall risk of death was lower during and following buprenorphine treatment than methadone, but again the difference did not reach statistical significance.

While treatment with methadone has been shown to reduce overall mortality in heroin users, both the early weeks of treatment and the period immediately after leaving treatment are associated with increased risk of death. Buprenorphine has been shown to be a safer option in some small studies.