Tobacco-, alcohol-, and drug-attributable deaths and their contribution to mortality disparities in a cohort of homeless adults in Boston.

Objectives: We quantified tobacco-, alcohol-, and drug-attributable deaths and their contribution to mortality disparities among homeless adults.

Methods: We ascertained causes of death among 28 033 adults seen at the Boston Health Care for the Homeless Program in 2003 to 2008. We calculated population-attributable fractions to estimate the proportion of deaths attributable to tobacco, alcohol, or drug use. We compared attributable mortality rates with those for Massachusetts adults using rate ratios and differences.

Results: Of 1302 deaths, 236 were tobacco-attributable, 215 were alcohol-attributable, and 286 were drug-attributable. Fifty-two percent of deaths were attributable to any of these substances. In comparison with Massachusetts adults, tobacco-attributable mortality rates were 3 to 5 times higher, alcohol-attributable mortality rates were 6 to 10 times higher, and drug-attributable mortality rates were 8 to 17 times higher. Disparities in substance-attributable deaths accounted for 57% of the all-cause mortality gap between the homeless cohort and Massachusetts adults.

Conclusions: In this clinic-based cohort of homeless adults, over half of all deaths were substance-attributable, but this did not fully explain the mortality disparity with the general population. Interventions should address both addiction and non-addiction sources of excess mortality.