Individual and neighbourhood social capital and all-cause mortality in Brazilian adults: a prospective multilevel study

Objective: The relationship between social capital and mortality is not clear-cut. There have been few longitudinal studies investigating this association so far. The objective was to assess the effect of different dimensions of social capital on mortality among adults of a Brazilian city.

Study design: This is a prospective multilevel study. Baseline data were obtained from a population-based random sample of 846 adults (aged 18 years or more) residing in 38 neighbourhoods (census blocks).

Methods: Participants were interviewed in 2006-7 and their vital status investigated in 2013. Social capital was assessed by five scales (social cohesion, informal social control, neighbours' support, social action and political efficacy). The outcome was all-cause mortality. Data analysis used multilevel logistic regression models.

Results: At the individual level social cohesion was positively related to mortality in the unadjusted model but this association lost significance after adjustment for other variables in multivariable models. At the neighbourhood level, high mortality rates were associated with low social action independently of demographic, socio-economic, behavioural and health-related variables.

Conclusion: We found more evidence for a contextual than individual level effect of social capital on mortality.