Some Biases That Hide the Gompertz Law of Mortality at Old Ages and Some Statistical Evidence That Life Expectancy Will Plateau

Nicolas Brouard, Institut National d'Études Démographiques (INED)

After the huge decrease of infectious diseases which had reached low levels by the end of the XXth century, the force of mortality began to fit more closely a Gompertz law. Despite the attrition of the most frail, the observed law of mortality in France at least is still a Gompertz law without a deceleration of probability of dying with increasing age. Biases in a French centenarians survey induced an artificial plateau. Aggregation of cohorts of different countries as well as increasing the age range in order to increase the statistical power of the estimates are at the price of an artificial plateau. Thus, reaching the age 120 doesn't seem plausible for humans. Modal age at death in a period life table is slightly increasing demonstrating a slow increase in the slope of the Gompertz line, reducing the gain in life expectancy which will plateau during the next 100 years.