Aim: To examine the reliability and validity of the Geriatric Depression Scale-15 (GDS-15) and the Patient Health Questionnaire-9 (PHQ-9) for evaluating depression in older adults.
Methods: A total of 1546 participants aged ≥60 years were investigated face-to-face with the PHQ-9 and GDS-15 anonymously. Internal consistency reliability was evaluated with Cronbach's α, and structural equation modeling was used to study the construct validity of the scale. Logistic regression was used to discusses the impact of demographic characteristics on the scale.
Results: The consistency rate between the GDS-15 and PHQ-9 was 96.10%. The Cronbach's α and split-half reliability in the scales were >0.7. The model fit indices χ2 /df., comparative fit index and root mean square error of approximation in the GDS-15 were 2.769, 0.815 and 0.077, respectively. The minimum fit function χ2 in the PHQ-9 model was 93.742, with 27 df., the comparative fit index was acceptably low (comparative fit index 0.837) and the root mean square error of approximation was acceptably high (root mean square error of approximation 0.118). Item standardized path regression coefficients of the GDS-15 model varied between 0.07 and 0.76, among which the coefficients of item 2 and item 9 were 0.12 and 0.07, respectively. Whereas in the PHQ-9, the item standardized path regression coefficients were high (r > 0.45), except for item 3 (r = 0.34). The GDS-15 was affected by urban-rural distribution (OR = 2.104, P = 0.027), whereas the PHQ-9 was affected by sex (OR = 4.266, P = 0.007).
Conclusions: The similar psychometric performance of the PHQ-9, along with its ease of use and relative brevity, makes it attractive compared with the longer GDS-15 for use in Chinese older adults, whereas the influence of sex distribution on the PHQ-9 should be paid attention to. Geriatr Gerontol Int 2020; 20: 138-143.
Keywords: Elderly; Geriatric Depression Scale-15; Patient Health Questionnaire-9; Psychology.
© 2019 Japan Geriatrics Society.