Old age mortality in Japan: Does the socioeconomic gradient interact with gender and age?

Objectives. There is limited knowledge concerning how the effects of socioeconomic status (SES) on mortality interact with gender and age. In addition, current studies are largely based on data from the Western nations. The validity of prior observations needs to be further evaluated. This research examines socioeconomic inequalities in old age mortality in Japan, with a special emphasis on how inequalities interact with gender and age. Methods. Data came from a 5-wave panel study of a national probability sample of 2,200 elderly Japanese conducted between 1987 and 1999. Hazard rate models involving time-varying covariates were used to ascertain the direct and indirect effects of SES. In addition, interaction effects involving SES variables with age and gender were evaluated. Results. In contrast to prior findings from the Western developed nations, there is an educational crossover effect on mortality among older men, in that, at advanced age, those with less education live longer than those with higher education. On the other hand, there is some evidence that educational differences in the risk of dying tend to converge in the 70-79 age group. More interestingly, there is a crossover in the effect of education among the 80 and older age group. Discussion. The observation that educational crossover exists only among elderly men may be because of gender and SES differences in causes of death, morbidity, and health behavior. On the other hand, possible explanations for age differences in the educational crossover include selective survival and cohort effects.