Examining mortality differential between a long-living community in Sardinia and the Italian population: a longitudinal analysis
Keywords:differential mortality, crossover, longitudinal analysis, life table, Italy
Progressive gains in life expectancy have brought increasing aging of developed countries’ populations and stimulated researches with respect to the limit of lifespan, the increasing presence of centenarians and the possible determinants of their “successful” ageing. In the international framework the population of the region of Sardinia was characterized by exceptional longevity. Through the comparison of life tables’ rates and life expectancy estimates of birth cohorts born in the period 1872-1910, this paper reports analyses of differences in overall mortality between Italy and the long-living community of Sardinia. The adoption of a longitudinal approach allows us to explore whether the previously detected differences at advanced ages are also observable in other age groups. In addition, the study focuses on the occurrence of mortality crossover as an indicator of significant mortality differences between populations. Results show that differences between the two populations are not limited to oldest old ages. Crossover points in mortality rates are observed in the first years of life and at age 50 years. Both intersections represent the points where differences in life expectancy are the highest. At age 5 years differences are of 1.8 years for females and 3.6 years for males, while at age 50 years they are respectively 1.5 years for females and 3.7 years for males. The observed differences suggest that possible explanations for differential mortality and crossover might be related to selection process timing and dynamics which could be determined by genetics, and specific causes of death, as well as by behavioural and environmental factors.
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