Accuracy of the 15-item Geriatric Depression Scale (GDS-15) in a Community Sample of the Oldest Old

Background: Cognitive impairment is common in the oldest old. This might influence the sensitivity and specificity of the 15-item Geriatric Depression Scale (GDS-15). Few studies, however, have included subjects older than 85 years to evaluate the GDS-15 as a screening instrument for depression.

Objective: To assess the sensitivity and specificity of the GDS-15 in a community sample of the oldest old.

Methods: Seventy-nine subjects aged 85 and over were enrolled in the study. The GDS-15 and the Mini-Mental State Examination (MMSE) were administered by a trained interviewer. Within two days the Geriatric Mental State (GMS)/AGECAT, was administered to obtain a clinical diagnosis of depression.

Results: Eight subjects (10%) were diagnosed with clinical depression. At a cut-off point of 3/4 the sensitivity and specificity of the GDS-15 were 88% and 76% respectively. In the group with MMSE scores of 28 and higher sensitivity was unaffected at all cut-off points while specificity increased. In the group with MMSE scores below 28 sensitivity was also unaffected at all cut-off points while specificity decreased.

Conclusion: The GDS-15 is a suitable instrument to diagnose depression in the general population of the oldest old. The optimal cut-off point depends on its intended use. In subjects with cognitive impairment the accuracy should be investigated further.