The impact of the summer 2003 heat waves on mortality in four Italian cities

This study evaluates the impact of the 2003 heat wave on cause-specific mortality and the role of demographic characteristics and socioeconomic conditions that may have increased the risk of mortality in four Italian cities: Bologna, Milan, Rome and Turin. Daily mortality counts, for the resident population by age, sex and cause of death were considered. Daily excess mortality was calculated as the difference between the number of deaths observed and the smoothed average. The impact of heat on health is measured in terms of maximum apparent temperature. The greatest excess in mortality was observed in the north west of Italy (Turin, +23% and Milan, +23%). The old (75-84 years) and the very old (85+ years) were the age groups most affected, and when stratifying by sex, the increase in mortality seemed to be greater among females. The greatest excess in mortality was registered in those with low socioeconomic status in Rome (+17.8%) and in those with lower education levels in Turin (+43%). The analysis of cause-specific mortality not only confirms results from previous studies of an increase in heat-related mortality by respiratory and cardiovascular diseases, but also shows a significant excess in mortality for diseases of the central nervous system and for metabolic/endocrine disorders. Results from 2003 highlight the necessity of targeting future prevention programmes at the susceptible sub-groups identified. The introduction of warning systems alongside efficient preventive plans and the monitoring of mortality during heat waves may represent a valid tool for the reduction of heat-related deaths.