The 15-item short form Geriatric Depression Scale (GDS-15) has been widely used for depression screening in multiple settings. However, few studies have specifically investigated the applicability of GDS-15 in longevous population. The aim of this study is to evaluate the psychometric property and item characteristic of the scale in Chinese community-dwelling longevous persons.
A total of 838 longevous people participated in this study. The reliability and validity of GDS-15 were analyzed with classical test theory, and the characteristics of each item were analyzed with item response theory using a three-parameters logistic model.
The Cronbach's α coefficient of the scale was 0.776. Spearman correlation coefficients between the GDS-15 score and each item were between 0.274 and 0.667 (P<0.01); the summed GDS-15 score was negatively associated with physical function, self-report health status and subjective well-being. Factors extracted using exploratory factor analysis accounted for 52.63% of the variance and the item loadings were between 0.513 and 0.828. The discrimination of each item ranged from 1.045 to 3.777; the difficulty ranged from -0.972 to 2.006, and the guessing parameter ranged from 0.000 to 0.499. The total information of GDS-15 was 13.645 when the subject's latent trait located at 1.131.
The sample used is representative of the longevous in rural communities, thus extrapolation to other populations requires further validation.
The GDS-15 has good applicability in depression detecting among Chinese longevous persons, especially for the individuals with moderate symptoms. Suggestions were provided on further improving its measurement precision.