Human mortality at extreme age: Power calculations make it implausible that there is an upper bound below 130 years

Human mortality at extreme age. Léo R. Belzile, Anthony C. Davison, Holger Rootzén and Dmitrii Zholud. Royal Society Open Science, Volume 8, Issue 9, September 29 2021. https://doi.org/10.1098/rsos.202097

Abstract: We use a combination of extreme value statistics, survival analysis and computer-intensive methods to analyse the mortality of Italian and French semi-supercentenarians. After accounting for the effects of the sampling frame, extreme-value modelling leads to the conclusion that constant force of mortality beyond 108 years describes the data well and there is no evidence of differences between countries and cohorts. These findings are consistent with use of a Gompertz model and with previous analysis of the International Database on Longevity and suggest that any physical upper bound for the human lifespan is so large that it is unlikely to be approached. Power calculations make it implausible that there is an upper bound below 130 years. There is no evidence of differences in survival between women and men after age 108 in the Italian data and the International Database on Longevity, but survival is lower for men in the French data.

7. Discussion

The results of the analysis of the newly available ISTAT data agree strikingly well with those for the IDL supercentenarians and for the women in the France 2019 data. Once the effects of the sampling frame are taken into account by allowing for truncation and censoring of the ages at death, a model with constant hazard after age 108 fits all three datasets well; it corresponds to a constant probability of 0.49 that a living person will survive for one further year, with 95% confidence interval (0.47, 0.50). Power calculations make it implausible that there is an upper limit to the human lifespan of 130 years or below.

Although many fewer men than women reach high ages, no difference in survival between the sexes is discernible in the ISTAT and the IDL data. Survival of men after age 108 is lower in the France 2019 data, but it seems unlikely that this reflects a real difference. It seems more plausible that this is due to gender imbalance, some form of age bias or is a false positive caused by multiple testing.

If the ISTAT and France 2019 data are split by birth cohort, then we find roughly constant mortality from age 105 for those born before the end of 1905, whereas those born in 1906 and later have lower mortality for ages 105–107; this explains the cohort effects detected by [13]. Possibly the mortality plateau is reached later for later cohorts. The plausibility of this hypothesis could be weighed if further high-quality data become available.