Background: a death number increment compared to the previous years was observed in Italy for the year 2015; its causes are under study.
Objectives: to verify if the mortality occurred in Palermo Province (Sicily Region, Southern Italy) for the year 2015 was greater than the one observed in the previous period (years 2009-2014) and to find which death causes it would be attributable to.
Design: observed number of deaths in 2015 were compared with expected numbers calculated with the traditional analysis of direct adjusted rates, and with a 90% predictive interval estimated fitting a Generalized Additive Model (GAM), via a quasi-Poisson distribution of the observed deaths in the period 2009-2014; various measures of the environmental temperature were used as regressor. The latter method was used also to analyse causes of death.
Setting and participants: all deaths occurred in residents in Palermo Province in the years 2009-2015.
Results: for each population subgroup based on sex and residence, direct adjusted rates for 2015 were lower than those observed in the previous period, but for women resident in towns outside Palermo (observed/estimated ratio: 1.04; 95%IC 1.00-1.08). GAM analysis shows mortality excesses only in men aged more than 64 years; in Palermo residents, excesses were shown in the 2nd week of December; in residents in towns of the Province excesses were shown in the 2nd and 3rd week of February and in the 1st and 2nd week of August. In the death causes analysis, mortality excesses were shown for pneumonia and bronchial pneumonia in the 1st and 2nd weeks of January; 3rd week of February; in the 1st, 2nd and 4th week of August; and in the 1st week of October. For infectious diseases, these excesses were observed in the 1st week of March.
Conclusions: it is plausible that in some weeks of the year 2015 there have been a mortality excess; however, as all-year mortality is lower or equal to that of the previous periods, the Authors believe that there is an harvesting effect, that is a mortality displacement that does not affect total mortality.