Associations between socioeconomic index and mortality in rural and urban small geographic areas of Catalonia, Spain: Ecological study

Objective: To analyse the association between MEDEA (Mortality in small areas of Spain and socioeconomic and environmental inequalities) index and mortality in urban and rural areas of Catalonia. Methods: An ecological study based on the analysis of census section. The data source used for census section and variables to calculate the MEDEA index was the census (2001). Mortality data were obtained from System for the Development of Research in Primary Care (SIDIAP). The census sections were classified as rural or urban. The association between mortality and the socioeconomic index was analysed as categorical variable (quintiles). Poisson models were fitted to study the association between MEDEA index and mortality. Analysis was done with the STATA software, version 12. Results: In January 2009, a total of 4,526,071 adults (> 14 years old) were assigned to ICS (Institut Català de la Salut ) primary healthcare centres. The identified population lived in 5,214 census sections out of a total of 5,222 existing areas, from which 4096 (78.5%) were urban. The association between MEDEA quintiles and mortality was significant for urban areas excluding Barcelona: excess mortality was 5% (IRR = 1.05 IC 95% 1.01-1.10), being higher in urban areas (IRR = 1.11 95% CI 1.08 to 1.15) and even higher in Barcelona (IRR = 1.24 95% CI 1.18 to 1.31). This association was not significant for rural areas (IRR = 0.95 CI 95% 0.88-1.02). Conclusions:Socioeconomic deprivation, measured with the MEDEA index, was related with an increase in total mortality in urban areas of Catalonia. In rural areas there was no association with mortality.