Local mortality patterns in Italy at the beginning of the 21st century

We analysed mortality levels and trends at the municipal level in Italy between 2002 and 2018, covering approximately 8000 local administrative units. Detailed mortality data at this level are unavailable, and apparently only crude death rates can be calculated (deaths divided by the average, i.e. mid-year, population). To overcome this limitation, we calculated standardised mortality ratios (SMR), comparing observed deaths to expected deaths derived by applying national age-specific mortality rates to local population age structures. We validated this approach, examined its properties, and used it to investigate local mortality patterns across Italy. Our findings highlight limited territorial heterogeneity in SMR, although with a slight increase over time: the coefficient of variation rose from 12.5% to 15%. The between-region variance component also increased, while the within-region component remained predominant, accounting for approximately 80% of the total variance. Selected ecological factors, particularly an Istat-developed frailty index for municipalities, were found to correlate with small-scale mortality patterns. Global spatial regression models (spatial autoregressive—SAR and spatial error—SEM) further revealed strong spillover effects influencing local mortality.