Differential Mortality in a Long-Living Community in Sardinia (Italy): A Cohort Analysis

Abstract

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.

Examining mortality differential between a long-living community in Sardinia and the Italian population: a longitudinal analysis

“…On the one hand, this result points out differences in mortality variations during the life course in the examined populations, but -on the other hand -it calls into question the appropriateness of a comparison of populations so different in size, as well as the quality of the data (Coale & Kisker, 1986;Scherbov & Ediev, 2011). With respect to the first factor, the available period data on general mortality level shows that the mortality experiences of the examined populations have similar profiles (Salaris, 2014). There are no significant differences in the impact of important historical events like WWI, WWII and Spanish flu epidemic (Tognotti, 1996;Cannas, 2007;Salaris, 2010).…”

“…This choice is for some aspects controversial, as it assumes that the survival experience of individuals born over a period of about 40 years is similar and does not take into account the possible confounding effects of individual characteristics and/or cohort experience. However, prior analysis of birth cohort data from Villagrande Strisaili showed that, despite no observation of a secular trend in survival among decennial cohorts, mortality differentials between cohorts were limited to adult ages and shown not to have impacted on the ageing process (Salaris, 2014). Table 2 reports age-specific mortality rate estimates from birth to age 80 years for Italy and Villagrande Strisaili by sex.…”

“…These include Okinawa in Japan (Willcox et al, 2001;Robine et al, 2003;Poulain & Naito, 2004;Cheung & Robine, 2007;Poulain, 2011), the peninsula of Nicoya in Costa Rica (Rosero-Bixby, 2008;Davinelli et al, 2012;Rehkopf et al, 2013), and the region of Sardinia in Italy (Deiana et al, 1999;Passarino et al, 2001;Poulain et al, , 2011Gatti & Salaris, 2004;Caselli & Lipsi, 2006;Salaris, 2010Salaris, , 2014Orrù, 2011;Pes et al, 2013;Salaris et al, 2013).…”

Consanguinity and Late Fertility: Spatial Analysis Reveals Positive Association Patterns

“…We focused on the Sardinian population since, as a result of the insular environment and its isolation, it is characterized by a fairly homogeneous biological and socioeconomic context and is thereby suitable for investigation of the possible determinants of complex traits. Among these, extreme longevity is one of the most studied: several works highlighted local heterogeneities in its spatial pattern and in the possible biological, environmental and behavioural determinants and their mutual interactions (Poulain et al., ; Scola et al., ; Pes et al., ; Salaris, ).…”