Depression and related syndromes are well identified in older adults. Depression has been reported to increase the incidence of a multitude of somatic disorders. In older adults, the severity of depression is associated with higher mortality rates. The aim of the study is to examine whether the effect of depression screening on mortality is different between individuals with different physical health status. In order to meet this aim, we will first reprove the relationship between depression and mortality rate, and then we will set a subgroup analysis by using self-reported health (SRH) status. Our data source, Taiwan Longitudinal Study on Aging (TLSA), is a population-based prospective cohort study that was initiated by the Health Promotion Administration, Ministry of Health and Welfare, Taiwan. The depression risk was evaluated by 10-items Center for Epidemiologic Studies Depression (CES-D-10), we set 3 CES-D-10 cutting points (5, 10, and 12) and cut our subjects into four groups. Taking mortality as an end point, we use the Taiwan National Death Registry (TNDR) record from 1999 to 2012. Self-rated health (SRH) was taken as an effect modifier between depression and mortality in the elderly group, and stratification took place into three groups (good, fair, poor). The case numbers of 4 CES-D-10 groups were 2253, 939, 285 and 522, respectively. After dividing into 4 CES-D-10 groups, the mortality prevalence rose as the CES-D-10 level grew (40.7%, 47.82%, 54.39% and 67.62%, respectively). In the subgroup analysis, although the p-value of log-rank test showed <0.05 in three groups, as the SRH got worse the Hazard Ratio became more significant (p = 0.122, 0.033, <0.001, respectively). Kaplan−Meier (K-M) survival estimates for different CES-D groups in SRH were poor, and we can see the curves representing second and third CES-D group going almost together, which may suggest the cutting point of CES-D-10 in predicting depression risk should be adjusted in the relatively unhealthy elderly. The importance of the relationship between depression and mortality is re-emphasized in our study. Moreover, through joining SRH in our analysis, we can conclude that in self-rated poor health any sign of depression may lead to a rise in mortality. Therefore, we should pay attention to the old age group’s psychological status, and remember that depressive mood should be scrutinized more carefully in the elderly who feel themselves to be unhealthy.
Keywords: CES-D; TLSA; depression; mortality; self-rated health.