Methadone increases death risk in first four weeks of treatment for opioid dependence
Patients who start treatment for dependence on opioids are five times as likely to die in the first four weeks when they are prescribed the most commonly used treatment, methadone, than with an alternative treatment, buprenorphine, a study by researchers at the University of Bristol, King's College London and the National Drug and Alcohol Research Centre at UNSW in Australia has found.
The study, published today [16 Sep] in The Lancet Psychiatry, reviewed the records of 32,033 patients who had started treatment with methadone or buprenorphine between 2001 and 2010. Patients who started treatment with buprenorphine were less likely to die from any cause, including drug-related causes, in the first four weeks of treatment. However, after four weeks there was little difference in risk of death between methadone and buprenorphine.
Around 50,000 Australians (and over 100,000 people in the UK) currently receive opioid pharmacotherapy treatment for dependence on heroin or other opioids. Around two thirds of these are being treated with methadone with the remainder on buprenorphine, according to figures from the Australian Institute of Health and Welfare. Buprenorphine is considered to be safer as it is less likely to cause respiratory depression (problems breathing), but patients are more likely to drop out of treatment than with methadone. Both treatments are endorsed by the World Health Organisation.
Dr Jo Kimber, one of the study's lead authors and a researcher at the National Drug and Alcohol Research Centre UNSW and King's College London, said: "Clinicians providing opioid substitution treatment face an important dilemma: which is more likely to reduce patient risk, buprenorphine or methadone?
"Buprenorphine is argued to have a superior safety profile to methadone but a higher drop-out rate. Our data suggests at least at the beginning of treatment for heroin use that buprenorphine has clear benefits over methadone in reducing mortality risk."
Professor Louisa Degenhardt at the National Drug and Alcohol Research Centre and one of the study's authors, added: "The findings support a stepped approach to treatment. Opioid substitution therapy is proven to be a cost effective and safe treatment for opioid dependence. It not only reduces risk of death but also involvement in crime and imprisonment.
Professor Matthew Hickman, Professor in Public Health and Epidemiology at the University of Bristol, said: "These findings are of importance to GPs treating patients with drug-dependency problems, one way to reduce risks might be to commence treatment on buprenorphine for the first four weeks and then switch to methadone at a later stage without increased risk."
More information: "Mortality risk of opioid substitution therapy with methadone versus buprenorphine: a retrospective cohort study." The Lancet Psychiatry, DOI: dx.doi.org/10.1016/S2215-0366(15)00366-1