Zung's Depression Scale as a Predictor of Death in Elderly People: a Cohort Study in Hokkaido, Japan

Abstract

The relation between each question in the Self-rating Depression Scale (SDS) of Zung and mortality in elderly people was investigated. Subjects were 2,166 inhabitants aged from 60 to 74 years in the Hidaka district of Hokkaido Prefecture, Japan, who were the same as in our previous prospective study concerning mental depression and mortality (J. Epidemiol. 1997). They were followed until February 1996. Among the original 20 questions of the SDS, 12 ones showed significant risk ratio for mortality (those whose score was 3 or 4 vs 1 or 2; P < 0.01). The mortality of those whose average score of the 12 questions was more than 2.4 (severe depression) was 157.2 per 1,000, which was about 5.8 time as high as that of those who were not depressive (average score < 2.0). The 12 questions showed different risk ratios concerning the mortality of cancer, heart disease and cerebrovascular disease. The questions "Morning is when I feel the best" and "My heart beats faster than usual," e.g., showed a significant risk ratio only for the mortality of heart disease (3.96) and for that of cerebrovascular disease (16.49), respectively (P < 0.01). Similar results were obtained from the subjects without respective diseases at the time of survey. Using these 12 questions, the risk for death and its cause can be estimated to a certain extent, and consequently, social supports can be given more effectively and more carefully.