Differential mortality in a long-living community in Sardinia (Italy): a cohort analysis.

The majority of studies on longevity in Sardinia point to an exceptional level of longevity, particularly for males, in this region of Italy. This study used individual data, considering selected groups of individuals such as centenarians, or focusing on cohorts of newborns in a large time period, that have previously been treated as a single group. An analysis on decennial birth cohorts from 1872 to 1911 in a selected village located in the Blue Zone area of longevity in Sardinia was used to gain insight into sex differentials in mortality in this area of high longevity and to separate differences between cohorts' experiences, considering the possible role of significant events in determining differential mortality among them. The results show that there is not a secular trend in survival in the birth cohorts under study, but rather that several points of mortality convergence and crossover occur, which make the estimates derived from conventional sensitivity tests of survival curves unreliable. Differences among birth cohorts' experiences are more marked among the male population and at early adult ages. External events are shown to play a relevant role in mortality variations, despite not having an impact on the ageing process. The results highlight that, although there are not statistically significant differences between the two sexes, the male population is exposed to a higher risk of death and proves to be more vulnerable to external changes. This suggests that extreme contextual conditions, both favourable and unfavourable, may significantly affect the mortality trajectories of a population.