Systematic reviews have shown that methadone maintenance treatment significantly reduces heroin use compared with other treatments,1 and it also reduces HIV risk behaviour among injecting drug users.2 Not surprisingly, it is on the World Health Organization’s list of essential medicines.3 In the linked prospective cohort study (doi:10.1136/bmj.c3172) Kimber and colleagues describe the effect of opiate substitution treatment on mortality and time to long term injection cessation.4

The study, which is based on observational data from a single primary care facility in Edinburgh, found that longer duration on opiate substitution treatment (primarily methadone) was associated with reduced mortality, but that it was also associated with a lower likelihood of injection cessation. Although the association with improved survival might be expected on the basis of past research,1 2 the negative association between opiate substitution treatment and injection cessation is curious. Despite the limitations of the study, which Kimber and colleagues acknowledge, the study overall supports the already extensive evidence base for using methadone as a first line treatment for opioid …