The shifting pattern of cause‐specific mortality in a cohort of human immunodeficiency virus‐infected and non‐infected injecting drug users

Abstract

To monitor changes in cause-specific mortality before and after 1997 according to human immunodeficiency virus (HIV) serological status in a cohort of injecting drug users (IDUs) observed for a 17-year period (1987--2004). Community-based prospective cohort study of IDUs recruited in three acquired immunodeficiency virus (AIDS) prevention centres (1987--96) and followed-up until to 2004. We obtained annual overall mortality rates and mortality rates by specific causes according to HIV status. Poisson regression models were adjusted to compare mortality rates between calendar periods. Significant changes in slope trends were evaluated by join-point regression. Disease-specific mortality rates were estimated using competing risk models. From 7186 IDUs recruited (80677.218 person-years), 1589 deaths were observed with an overall mortality rate of 19.7 per 1000 person-years (95% CI, 18.8-20.7). This rate decreased from 22.9 per 1000 (95% CI, 21.4-24.7) before 1997 to 17.4 per 1000 (95% CI, 16.3-18.6) after 1997 [relative risk (RR) 0.83; 95% confidence interval (CI), 0.75-0.92]. Risk of death for HIV-positive was four times higher than for HIV-negative (RR 4.08; 95% CI, 3.63-4.58). Among HIV-positive individuals a significantly decreased change point in trend was found in 1997 for both total and AIDS mortality. HIV-negative individuals showed a similar pattern for drug overdose, suicide and accident mortality. Both groups showed an increase in proportional mortality by liver-related causes, cardiovascular diseases and cancer. Furthermore, a progressively increasing trend was observed for the three causes. However, there were no significant differences according to serological groups. Cardiovascular and cancer mortality are increasing among IDUs, but the increases are not related to HIV infection. We have not found a link between highly active antiretroviral therapy (HAART) introduction and increases in mortality for specific causes.