A prospective study of mortality among drug misusers during a 4-year period after seeking treatment

The opportunity to study deaths as they occur within the framework of a prospective cohort study is relatively uncommon. This study investigates deaths among drug misusers over a 4-year period, with specific attention to the circumstances and causes of death, and risk factors for mortality. The study also critically examines the recording of drug-related deaths.

Prospective cohort study of 1075 drug misusers recruited to 54 treatment programmes during 1995.

Data derived from interviews conducted with clients at intake, death certificates and post-mortem examinations.

The annual mortality rate was 1.2%, about six times higher than that for a general, age-matched population. Fourteen per cent of the deaths were due to self-inflicted injuries, accidents or violence and 18%, were due to medical causes. The majority of deaths (68%) were associated with drug overdoses. Opiates were the drugs most commonly detected during post-mortem examinations. In the majority of cases, more than one drug was detected. Polydrug use and, specifically, heavy drinking, and use of benzodiazepines and amphetamines, were identified as risk factors for mortality. Anxiety and homelessness were also predictive of increased mortality.

We suggest that drug misusers and those working with drug misusers need to be more alert to the risks of polydrug use, including the combined use of alcohol with illicit drugs. The study revealed inconsistencies in the recording of drug-related deaths on death certificates. The routine recording of all substances detected during toxicological examination would improve the accuracy of death certification.