Is living on the coast associated with midlife multimorbidity in England and Wales? A cross-birth cohort analysis of the relationship between long-term residence and selective migration.

INTRODUCTION: The 2021 Chief Medical Officer's report highlighted that coastal communities have some of the worst health outcomes in England. The drivers of this spatial disadvantage are unclear. Moreover, some evidence suggests that living closer to the coast has protective health effects. This paper investigates the relationship between coastal residence and multimorbidity and assesses the role of selective migration and socioeconomic deprivation from adolescence to midlife in shaping health outcomes in coastal communities. METHODS: Longitudinal cohort study data are used from the 1958 National Child Development Study (NCDS) and the 1970 British Cohort Study (BCS). Coastal residence is defined using the Office for National Statistics' built-up areas in England and Wales. The analysis includes 13 691 respondents from NCDS and 14 683 from BCS, followed from birth through adolescence and midlife. Multimorbidity in midlife, defined as the presence of two or more doctor-diagnosed chronic conditions at age 55 years (NCDS) and age 46 years (BCS), is the outcome in the analysis. RESULTS: Although no association was found between coastal residence in adolescence and multimorbidity in midlife, coastal residence in midlife was associated with 1.21 (95% CI 1.00 to 1.28) higher odds of multimorbidity later in life in the earlier-born cohort, though this was attenuated by neighbourhood deprivation at age 42 years. Individuals who moved away from coastal areas between adolescence and midlife were significantly (p<0.05) less likely to report multimorbidity than those who moved to coastal areas. Neighbourhood deprivation was strongly associated with migration patterns, with those remaining in or moving to coastal areas significantly (p<0.05) more likely to live in deprived neighbourhoods at midlife. CONCLUSIONS: Coastal communities in England and Wales are experiencing a concentration of health disadvantage that is associated with socioeconomic deprivation and patterns of selective migration. These findings have important implications for public health policy and resource allocation in coastal regions.