What is the prevalence of multimorbidity in migrants, refugees, asylum seekers and displaced persons and its association with mortality? Findings from a systematic review

Problem

Multimorbidity, the presence of 2 or more long-term conditions (LTCs) is common and associated with poor health outcomes. Little is known about multimorbidity in migrant groups (including refugees, asylum seekers, and displaced persons). The aims of this systematic review are to:1. Assess what is known about the prevalence of multimorbidity in migrant populations.2. Determine the association between multimorbidity and mortality in migrant populations.

Approach

A systematic review was conducted following PRISMA-P guidelines. Five bibliographic databases (MEDLINE (Ovid), Embase (Ovid), CINAHL (EBSCOhost), The Cochrane Library (Wiley) and Scopus (Elsevier)) were searched (timeframe January 2000-March 2022) using the following concepts: 1) Migrant/refugees/asylum seekers/displaced persons/undocumented migrants, 2) multimorbidity, and 3) prevalence/mortality. Two reviewers independently screened titles, abstracts and full text articles before extracting data and assessing risk of bias using the Newcastle-Ottowa scale for observational studies. An independent third reviewer adjudicated on disagreements. Inclusion criteria: adults ≥18 years, migrant/refugees/asylum seekers/displaced persons/undocumented migrants; multimorbidity (measured by count of LTCs or a multimorbidity index); community, primary or secondary care setting; cross-sectional or observational study design; English or Spanish language. Studies measuring single LTCs or comorbidity were excluded. Findings are synthesised narratively.

Findings

2400 references identified, 747 excluded as duplicates, 1539 at abstract screening and 79 at full text screening. 8 additional articles were identified through reference list and citation checking. Overall, 38 full text articles were included: 33 cross-sectional studies, 5 cohort studies. Of these, 35 studies examined prevalence; 3 studies examined mortality. Cross-sectional studies ranged from small bespoke studies to largescale health registry data. Thus, participants ranged in number from 61 to 5,074,227. Most were conducted in Europe (n=22). Studies reported on multiple groups including immigrants/foreign-born (n=24), asylum seekers and refugees (n=12), undocumented/irregular migrants (n=4), displaced people (n=2). Multimorbidity was most commonly defined as ≥2 chronic diseases, although several papers only included a small number (4 or fewer) of LTCs (n=3) or mental health conditions only (n=12). As a result of these variations in definition of multimorbidity and migrants, the prevalence of multimorbidity (≥2 physical conditions) varied widely from 0.6% to 75.0%. The prevalence of mental health multimorbidity ranged from 16.0% to 45.0%. Multimorbidity increased with age and was generally higher in women compared to men. Where comparison was possible, migrants often had lower prevalence of multimorbidity compared to the native-born population, but some groups (e.g. refugees) may have higher prevalence. Migrants did not appear to be at greater risk of mortality compared to native-born populations.

Consequences

This review has provided new insights on the scale of multimorbidity in migrant populations and highlights areas requiring further research as well as providing evidence to inform future clinical practice and policy. Clear and consistent definitions for migrant groups is needed.