Rectangularization of Survival Curve

Rectangularization is the process that modifies the shape of the survival curve of a life table as the result of the mortality decline producing a postponement of mortality risks from lower to higher ages until a hypothetical natural limit to the human life span is reached. The consequence of these dynamics is that age-at-death increases and its variability decreases. The most frequently used indicators proposed to analyze survival curve changes are presented, as are some methods aimed at evaluating whether the observed life expectancy trend is better explained by specific modifications of the survival curve or of the age-at-death curve. Results from the most promising current research are presented and future directions are suggested.