Mortality in people experiencing homelessness: a systematic review and meta-analysis.

BACKGROUND: The association between homelessness and the type of homeless experience with all-cause and cause-specific mortality is uncertain. METHODS: Published studies were retrieved through a systematic search of MEDLINE, Embase PsycINFO, and Scopus from inception to December 2024. Unpublished data were identified from open-access data archives. We used random-effects meta-analysis to combine the effect estimates from published and unpublished data from 116 studies comprising 2 563 633 homeless people and 129 292 553 population controls. This review is registered at PROSPERO (CRD42023430984). RESULTS: The risk of all-cause mortality was increased in people exposed to homelessness compared with those unexposed [relative risk (RR) 2.21, 95% confidence interval (CI) 1.91-2.57, P < .001, I2 = 99.7], with risks similar in men (RR 4.04, 95% CI 2.87-5.21) and women (RR 3.58, 95% CI 2.35-4.82). Risks were higher in people who had slept rough (RR 7.63, 95% CI 3.29-11.97) than in those who had slept in homeless hostels/shelters (RR 3.44, 95% CI 2.10-4.77) and also elevated for people staying in low-cost hotels (RR 5.18, 95% CI 1.14-9.23). Summary RR estimates were elevated for 33 of the 36 (92%) causes of death. The highest risk of death was apparent for psychoactive-substance-use disorder (RR 21.38, 95% CI 14.44-31.67), accidental injuries (RR 13.15, 95% CI 5.46-31.69), and drug overdose (RR 11.65, 95% CI 6.97-19.48). Around half of the studies (57%) were of high quality. No studies were found in low-income countries. There was no evidence of publication bias. CONCLUSION: Compared with the general population, homeless people experience an increased risk of premature mortality. The most extreme inequalities were from deaths through psychoactive-substance-use disorder, accidents, and drug overdose. There are evidence-based treatments for psychoactive substance use and drug overdose, suggesting that some of these deaths are avoidable.