Sex-specific disease outcomes of HIV-positive and HIV-negative drug users admitted to an opioid substitution therapy program in Spain: a cohort study

BACKGROUND: Opioid substitution therapy has improved the survival of heroin users with and without HIV infection. We aimed to analyze sex differences in mortality rates and predictors of death among those admitted to a methadone treatment program (MTP). METHODS: Longitudinal study of patients enrolled in a MTP from 1992 to 2010. Socio-demographic and drug use characteristics, and markers of viral infections were assessed at entry. Vital status was ascertained by clinical charts and the mortality register. Four calendar periods were defined according to the introduction of preventive and treatment interventions in Spain. Predictors of death were analyzed by Cox regression models. RESULTS: 1,678 patients (82.8% men) were included; age at first heroin use was 18.6 years (IQR: 16–23 years), and age at first entry into a MTP was 30.7 years (IQR: 26–36 years). A total of 441 (26.3%) deaths occurred during 15,124 person-years (p-y) of follow-up (median: 9.2 years, IQR: 4–13 years). HIV infection was the main predictor of death in men (HR = 3.5, 95% CI: 2.1-5.7) and women (HR = 3.2, 95% CI: 1.2-8.7 ) and main cause of death was HIV/AIDS. Overall mortality rate was 2.9 per 100 p-y (95% CI: 2.7-3.2 per 100 p-y) and death rates decreased over time: 7.4 per 100 p-y (95% CI: 6.3-8.8 per 100 p-y) for the 1992–1996 period to 1.9 per 100 p-y (95% CI: 1.6-2.4 per 100 p-y) for the 2007–2010 period. In women, a slightly increase in mortality was observed in recent periods specifically among HIV-positive women (3.7 per 100 p-y in period 2002–2006 and 4.5 per 100 p-y in 2007–2010). CONCLUSIONS: Significant reductions in mortality of patients in MTP are observed after nineteen years of observation. However, HIV infection shows a great impact on survival, particularly among HIV-infected women. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/1471-2334-14-504) contains supplementary material, which is available to authorized users.