Mortality and cause of death in a cohort of people who had ever injected drugs in Glasgow: 1982-2012

Background
To describe all-cause and cause-specific mortality in a cohort of people who had ever injected drugs (PWID) with a low prevalence of HIV over 20–30 years.

Methods
Using a retrospective study design, identifying data from a cohort of PWID recruited between 1982 and 1993 through in-patient drug treatment services were linked to National Records for Scotland deaths data using probabilistic record linkage. We report all-cause and cause-specific mortality rates; standardized mortality ratios (SMR) across time, gender and age were estimated.

Results
Among 456 PWID, 139 (30.5%) died over 9024 person-years (PY) of follow-up. Mortality within the cohort was almost nine times higher than the general population, and remained elevated across all age groups. The greatest excess mortality rate was in the youngest age group, who were 15–24 years of age (SMR 31.6, 95% CI 21.2–47.1). Drug-related deaths declined over time and mortality was significantly higher among HIV positive participants. Although SMRs declined with follow-up, the SMR of the oldest age group (45–60) was 4.5 (95% CI 3.0–6.9). There were no significant differences in all-cause mortality rates between participants who were 25 years and older at cohort entry compared to younger participants.

Conclusion
Mortality rates remained higher than the general population across all age groups. Screening services that identify a history of injecting drug use may be an opportunity to address risk factors faced by an ageing population of PWID and potentially have implications for future health care planning.