Differences in mortality trends according to population density in two southern European countries, 2001-2019

The objective of this study was to estimate the magnitude and trend of overall mortality and mortality from the leading causes of death according to population density in Italy and Spain, during the first two decades of the 21st century.

This is a cross-sectional time-series design using anonymized data from all residents in Italy and Spain from 2001 to 2019.

Deaths and population data by age and sex, according to province of residence were obtained from the National Institutes of Statistics. Provinces were grouped into three categories based on their population density: low, medium and high. Annual age-standardized mortality rates were calculated from 2001 to 2019, in each population density category. The average annual percentage change (APC) in the mortality rate in each category was estimated using linear regression models and taking age-standardized mortality rates as dependent variable.

Overall mortality rates and mortality from the leading causes of death decreased between the beginning and the end of the period analyzed. The APC (95 % confidence interval) in the low, medium and high density categories was, respectively, -1.5 (-1.8,-1.3), -1.4 (-1.6, -1.2), -1.6 (-1.9, -1.4) in Italy and -1.4 (-1.6, -1.1), -1.8 (-2.0, -1.6) and -2.1 (-2.4,-1.9) in Spain. The high-density category also showed the largest reduction in mortality from most causes of death. As consequence, the mortality disadvantage found in that category at the beginning of the study period disappeared or reverted at the end of period.

During the first two decades of the 21st century, overall mortality and mortality from the leading causes of death showed greater reduction in the provinces with the highest population density in Italy and Spain. Future research should test the reasons that explain this greater mortality decline in the densely populated areas.