Usefulness of the 15-item geriatric depression scale (GDS-15) for classifying minor and major depressive disorders among community-dwelling elders

The 15-item geriatric depression scale (GDS-15) is a short form of GDS and is used to screen, diagnose, and evaluate depression in elderly individuals. Most previous studies evaluated the ability of GDS-15 to discriminate between depressive and non-depressive states. In this study, we investigated the multi-stage discriminating ability of GDS-15. A total of 774 participants, over 65 years of age were included (normal, n = 650; minor depressive disorder [MnDD], n = 94; major depressive disorder [MDD], n = 30). Multi-category receiver operating characteristic (ROC) surfaces were evaluated to identify three stages of geriatric depression. The optimal cutoff points were selected based on the volume under the ROC surface (VUS) and the Youden index. In the results of multi-category classification analyses, VUS of the GDS-15 of 0.61 was obtained, and optimal cutoff points of the GDS-15 for multiple stages of depression of 4 (between normal and MnDD) and 11 (between MnDD and MDD) were derived. The Youden index for the GDS-15 was 0.49, and the derived optimal cutoff points were 5 and 10, for the multiple stages, respectively. The overall diagnostic accuracy based on the Youden index was superior to that based on the VUS in the GDS-15. The participants’ cognitive function has potential to affect the GDS-15 score; nevertheless, the study included those with mild cognitive impairment. GDS-15 was a useful tool to classify stages of geriatric depression into either minor or major depressive disorder.