The Geriatric Depression Scale should be shortened: results of Rasch analysis

• Published in: International journal of geriatric psychiatry 2005-08, Vol.20 (8), p.783-789
• Main Authors: Tang, Wai Kwong, Wong, Eric, Chiu, Helen F. K., Lum, C. M., Ungvari, Gabor S.
• Format: Article
• Language: English
• Subjects: Adult; Adult and adolescent clinical studies; Age Distribution; Aged; Aged, 80 and over; Biological and medical sciences; Cognition Disorders - complications; Cognition Disorders - psychology; Depression; Depressive Disorder - complications; Depressive Disorder - diagnosis; Depressive Disorder - psychology; Educational Status; Female; Fundamental and applied biological sciences. Psychology; geriatric depression scale; Geriatric psychiatry; Geriatric psychology; Geriatrics; Hong Kong; Humans; Male; Medical diagnosis; Medical sciences; Mental depression; Middle Aged; Models, Statistical; Mood disorders; pneumoconiosis; Pneumoconiosis - complications; Pneumoconiosis - psychology; Psychiatric Status Rating Scales; Psychoanalysis; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; Rasch analysis; Severity of Illness Index; Sex Distribution
• ISSN: 0885-6230; 1099-1166
• DOI: 10.1002/gps.1360

Background The purpose of this study was to examine the unidimensionality, item fit, redundancy and differential item functioning (DIF) of the 15‐item version of the Geriatric Depression Scale (GDS) in a community sample of 300 Hong Kong Chinese patients with pneumoconiosis. Methods Participants were randomly selected from the case register of the Pneumoconiosis Compensation Fund Board of Hong Kong. A trained research assistant administered the GDS to all participants. A psychiatrist, who was blind to the GDS scores, conducted a structured clinical interview to diagnose depressive disorders according to the Diagnostic and Statistical Manual for Mental Disorders, Version IV (DSM‐IV) criteria. Results Of the 300 participants, 37 (12.3%) had a DSM‐IV diagnosis of depressive disorders. Eleven out of 15 items (73.3%) had INFIT/OUTFIT statistics between 0.7–1.3. Abbreviated versions were created by removal of misfit and redundant items resulting in similar overall performance as the original 15‐item GDS. None of the items had significant DIF for age, level of education and cognitive impairment. Conclusions Although the GDS was overall unidimensional, there was evidence of item redundancy indicating that a shortened version would be as adequate as the original version. Copyright © 2005 John Wiley & Sons, Ltd.