Factors associated with increased all-cause mortality during the COVID-19 pandemic in Italy

The number of excess deaths during February-March 2020 in Italy, in comparison with previous years, was considerably higher than the recorded COVID19-related deaths. The present study aimed to explore the association of excess mortality with some indices related to the COVID-19 pandemic and its management.

Data on all-cause mortality from 20 February-31 March in the years 2015-2020, and demographic, socioeconomic and healthcare organisation data of each Italian region were obtained from the Italian Institute of Statistics. Non-COVID-19-Imputed Excess Mortality (NCIEM) was calculated as the difference between the excess 2020 mortality and reported COVID-19 mortality. The association of NCIEM with the rate of COVID-19 cases, COVID-19 mortality and other potential moderators was assessed using linear regression models.

The nationwide number of excess deaths and COVID-19 deaths was 26,701 and 13,710, respectively, with a difference of 12,991. The NCIEM in different regions showed a direct correlation with COVID-19 mortality (r² = 0.61, p < 0.001) and total cases (r² = 0.30, p = 0.012), and an inverse correlation with cases/total tests ratio (r² = 0.49, p = 0.001). Direct correlations were also found with the proportion of institutionalised elderly, whereas inverse correlations were observed with prevalence of diabetes, cardiovascular mortality and density of general practitioners.

The impact of the COVID-19 pandemic on all-cause mortality was considerably greater than that indicated by official counts of victims. Limited testing capacity and causes of death other than COVID-19 could have contributed to the increase in overall mortality rates.