A longitudinal study of the impacts of area-level social cohesion on multimorbidity in Scotland

Abstract Background Multimorbidity is a growing global public health challenge, commonly referring to the co-occurrence of 2+ conditions but with varying measurements. Prior evidence has linked social cohesion with single health conditions; however, its impact on multimorbidity remains unclear. This study aims to examine the association between area-level social cohesion and multimorbidity and to explore whether this association will vary across multimorbidity measurements and levels of urban-rural classification. Methods Using a dataset that links the Scottish Longitudinal Study (5.3% of the Scottish population) with hospitalisation records (2001-2019) and an index that reflects area-level social cohesion (2012), focused on the cohorts of adults aged 40+, we used 3-level logistic regression to account for the clustered data structure of diagnosed chronic conditions over time within individuals within neighbourhoods. Results Areas with the highest social cohesion were observed to have the lowest risks of multimorbidity (p < 0.001), even after adjusting for area-level income deprivation. Varying by multimorbidity measurements, an inverted U-shaped pattern was observed between reduced area-level social cohesion and increased risks of having 2+ co-occurring chronic conditions; while a linear pattern was found for mental-physical multimorbidity. Moderated by levels of urban-rural classification, as compared to rural residents, urban residents were more sensitive to the impact of social cohesion on the co-occurrence of 2+ conditions; however, for mental-physical multimorbidity, no interaction effects between area-level social cohesion and urban-rural classification were found. Conclusions Although varying patterns were seen for different multimorbidity measurements, people living in areas with the highest area-level social cohesion were less likely to be multimorbid. This study offers new insights for developing effective place-based public health interventions. Key messages • This is the first longitudinal study that analysed the association between area-level social cohesion and multimorbidity using a nationally representative dataset based on secondary care data. • Area-level social cohesion affects multimorbidity, but its impact may vary by multimorbidity measurements and by urban-rural classification.