Inequalities in all-cause mortality by ethnicity in the United Kingdom: a systematic review and meta-analysis.

Background: Ethnic inequalities in health outcomes are a persistent concern in the United Kingdom (UK) and internationally. In this systematic review and meta-analysis, we aimed to quantify ethnic differences in all-cause mortality across the UK and explore the potential modifying roles of socioeconomic position (SEP) and country of birth. Methods: We searched Medline, Embase, Scopus, and Web of Science from inception to April 20, 2024, and identified grey literature via EThOS, ProQuest, Google, and data-sharing platforms. Eligible studies reported all-cause mortality by ethnicity or other commonly used measures such as country of birth or person or parents and surname in UK populations. Two reviewers independently conducted screening, data extraction, and risk of bias assessment using the ROBINS-E tool. Certainty of evidence was evaluated using GRADE. The review was registered with PROSPERO (CRD42019146143). Findings: Of 7672 records screened, 32 studies met inclusion criteria, supplemented by unpublished data from three cohort studies. Age-adjusted all-cause mortality was consistently lower among females of Bangladeshi (Relative Risk = 0.80, 95% CI 0.67-0.95), Indian (0.78, 0.68-0.88), Pakistani (0.85, 0.79-0.91), Black Caribbean (0.83, 0.81-0.85), Chinese (0.64, 0.61-0.69), and Mixed ethnicity (0.94, 0.90-0.98), and among males of Bangladeshi (0.89, 0.86-0.93), Indian (0.78, 0.69-0.88), Pakistani (0.76, 0.69-0.83), Black Caribbean (0.89, 0.85-0.93), and Chinese ethnicity (0.66, 0.50-0.87)), compared with White British individuals. In contrast, White Irish (1.20, 1.06-1.34) and White Scottish males (1.19, 1.11-1.27), and White Scottish females (1.18, 1.08-1.29), had higher mortality than other White British. Evidence on the role of SEP was inconclusive due to methodological heterogeneity. Evidence on the role of country of birth was also limited with wide and overlapping confidence intervals around the results stratified by country of birth (UK-born vs non-UK-born) in each ethnic group. However, the UK-born Black Caribbean population had higher relative mortality rate compared to the UK-born White British population (1.49; 0.98-2.28), although this did not quite reach statistical significance. Interpretation: Inequalities in mortality by ethnic group were consistent and substantial. The contribution of SEP to observed inequalities is complex and the quality of evidence is impacted by methodological heterogeneity. However, SEP disadvantage is unlikely to explain the lower relative mortality of non-white groups. The potential for inequalities within ethnic groups by country of birth has important policy implications, as this suggests the need to tailor public health strategies within ethnic groups by country of birth. However, more evidence is needed for most ethnic groups. As a result, we call for greater reporting of both ethnicity and country of birth in ethnic inequalities research in the UK. Funding: Australian Research Council Centre of Excellence in Population Ageing Research (Grant ID: CE170100PRO005).