Homelessness, type of homelessness, and risk of cause-specific mortality: a systematic review and meta-analysis of 116 studies comprising 2,563,633 homeless people and 129,292,553 population controls.

BACKGROUND

Homelessness might increase the risk of premature mortality, but evidence is scarce, imprecise, and is mostly limited to rough sleepers as opposed to more common types of homelessness.

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 Unpublished data were identified from open-access data archives. We used random-effects meta-analysis to combine effect estimates from published and unpublished data. This review is registered at PROSPERO (CRD42023430984).

FINDINGS: We included 116 studies from Europe, the USA, South America, Africa, Asia, and Australia. The meta-analysis of all-cause mortality comprised 110,892,271 people (1,618,049 exposed to homelessness). The risk of all-cause mortality was significantly increased in people exposed to homelessness (Relative risk [RR] 2·12 [95% CI 1·91-2·57], p<0·001, I2=99·7%), with risks similar in men (3·88, 2·69-5·06) and women (3·46, 2·17-4·70). This risk was most elevated in people who had slept rough (7·63, 3·29-11·97), followed by those who used low-cost hotels (5·18, 1·14-9·23), then hostels (3·44, 2·10-4·77). In analyses of cause-specific mortality (26,291,900 people, 1,202,205 homeless), summary RR estimates were elevated for 33 of the 36 (92%) causes of death and highest for deaths due to psychoactive substance use disorder (21·36, 14·44-31·67), accidental injuries (13·15, 5·46-31·69), drug-overdose (10·80, 6·37-18·31), and those that are alcohol-related (5·93, 1·10-22·04). No evidence of publication bias was detected.

INTERPRETATION: Homeless people experience an increased risk of premature mortality across an array of health outcomes. That the most extreme inequities have an interrelated aetiology suggests a cross-sectoral medical, housing, and social care response is required.

FUNDING: The Centre for Homelessness Impact, Health and Care Research Wales, UK Medical Research Council (MR/P023444/1) and the US National Institute on Aging.