A statistical analysis of death rates in Italy for the years 2015-2020 and a comparison with the casualties reported for the COVID-19 pandemic

TL;DR

This study analyzes Italian mortality data from 2015-2020, identifying patterns and excess deaths during COVID-19, and compares official COVID-19 death reports with overall excess mortality to understand the pandemic's impact.

Contribution

It introduces a statistical approach using sinusoidal fitting and asymmetric peak modeling to quantify excess mortality and compare it with COVID-19 death reports in Italy.

Findings

Identified seasonal mortality patterns with peaks during winter and summer.

Quantified excess deaths during COVID-19 using Gompertz function fitting.

Found discrepancies between reported COVID-19 deaths and excess mortality data.

Abstract

We analyze the data about casualties in Italy in the period 01/01/2015 to 30/09/2020 released by the Italian National Institute of Statistics (ISTAT). The data exhibit a clear sinusoidal behavior, whose fit allows for a robust subtraction of the baseline trend of casualties in Italy, with a surplus of mortality in correspondence to the flu epidemics in winter and to the hottest periods in summer. While these peaks are symmetric in shape, the peak in coincidence with the COVID-19 pandemics is asymmetric and more pronounced. We fit the former with a Gaussian function and the latter with a Gompertz function, in order to quantify number of casualties, the duration and the position of all causes of excess deaths. The overall quality of the fit to the data turns out to be very good. We discuss the trend of casualties in Italy by different classes of ages and for the different genders. We finally compare the data-subtracted casualties as reported by ISTAT with those reported by the Italian Department for Civil Protection (DPC) relative to the deaths directly attributed to COVID-19, and we discuss the differences.