Background People affected by homelessness, imprisonment, substance use, sex work or severe mental illness experience substantial excess ill health and premature death. Though these experiences often co-occur, health outcomes associated with their overlap have not previously been reviewed. We synthesised existing evidence on mortality, morbidity, self-rated health and quality of life among people affected by more than one of these experiences. Methods In this systematic review and meta-analysis, we searched Medline, Embase, and PsycINFO for peer-reviewed English-language observational studies from high-income countries published between 1 January 1998 and 11 June 2018. Two authors undertook independent screening, with risk of bias assessed using a modified Newcastle-Ottawa Scale. Findings were summarised by narrative synthesis and random-effect meta-analysis. Results From 15 976 citations, 2517 studies underwent full-text screening, and 444 were included. The most common exposure combinations were imprisonment/substance use (31% of data points) and severe mental illness/substance use (27%); only 1% reported outcomes associated with more than two exposures. Infections were the most common outcomes studied, with blood-borne viruses accounting for 31% of all data points. Multiple exposures were associated with poorer outcomes in 80% of data points included (sign test for effect direction, p<0.001). Meta-analysis suggested increased all-cause mortality among people with multiple versus fewer exposures (HR: 1.57 and 95% CI: 1.38 to 1.77), though heterogeneity was high. Conclusion People affected by multiple exclusionary processes experience profound health inequalities, though there are important gaps in the research landscape. Addressing the health needs of these populations is likely to require co-ordinated action across multiple sectors, such as healthcare, criminal justice, drug treatment, housing and social security. PROSPERO registration number CRD42018097189.
Bibliographical noteFunding Information:
Funding ET, RT and SVK are funded by the Medical Research Council grants MC_UU_12017/13 and MC_UU_12017/15 and the Chief Scientist Office grants SPHSU13 and SPHSU15. In addition, ET is funded by a Chief Scientist Office Clinical Academic Fellowship (CAF/17/11), SVK by an NRS Scottish Senior Clinical Fellowship (SCAF/15/02), RT by a Wellcome Trust Research Fellowship for Health Professionals (218105/Z/19/Z), AK by a Wellcome Trust Clinical PhD Programme Fellowship (203919/Z/16/Z), AKP by a Medical Research Council PhD Studentship (MC_ UU_12017/13), DL by a National Institute for Health Research Doctoral Research Fellowship (DRF-2018-11-ST2-016) and RA by a Wellcome Clinical Research Career Development Fellowship (206602).
© Authors 2021
- drug misuse
- health inequalities
- mental health