Rectangularization of the Survival Curve in Korea, 1966-1995

Cho, Kyung Hwan; Park, Yong Gyu; Roh, Yong Kyun

Abstract

BACKGROUND: In this article, authors determine whether rectangularization of survival curve occurred in Korea in the period 1966-1995. Rectangularization is defined as a trend toward a more rectangular shape of the survival curve due to increased survival and concentration of deaths around the mean age of death. Authors distinguish between absolute and relative rectangularization, depending on whether an increase in life expectancy is accompanied by concentration of deaths into a smaller age interval or into a smaller proportion of total life expectancy.
METHODS
In this study, the authors intended to demonstrate the survival curve according to the year 1966 and 1970 to 1995. For these purpose, the authors used the annual mortality data published by the National Statistical Office from 1966 to 1995 in Korea. Authors used measures of variability based on Keyfitz' H and the standard deviation, both life table-based. Our results show that absolute and relative rectangularization of the entire survival curve occured except mortality data of 1966 which has little reliability over the complete period.
RESULTS
In this study, authors observed relative and absolute rectangularization and the survival curves of 1970 to 1995 shows the convergence between mid-60s and mid-80s. All the Keyfitz' H, NH, SD and CV decreased while the life expectancy increased in the period of 1970 to 1995. This result is similar to the mortality curve suggested by Fries according to his compression of morbidity hypothesis.
CONCLUSIONS
According to Keyfitz theory, rectangularization happens to survival curve in Korea. The implications of the recent rectangularization at older ages for achieving compression of morbidity have to be exactly understood. So, the authors suggest that health policy and research must be directed to the preventive health service and health promotion to reduce morbidity, postpone infirmity and to warrant the quality of life for senior people.