Differential item functioning of the Geriatric Depression Scale in an Asian population.
BACKGROUND
The Geriatric Depression Scale (GDS) is widely used for screening and assessment of major depressive disorder (MDD). Screening scales are often culture-specific and should be evaluated for item response bias (synonymously differential item functioning, DIF) before use in clinical practice and research in a different population. In this study, we examined DIF associated with age, gender, ethnicity and chronic illness in a heterogeneous Asian population in Singapore.


METHODS
The GDS-15 and Structured Clinical Interview for DSM-IV diagnosis of MDD were independently administered by interviewers on 4253 non-institutionalized community living elderly subjects aged 60 years and above who were users of social service agencies. Multiple Indicator Multiple Cause latent variable modelling was used to identify DIF.


RESULTS
We found evidence of significant DIF associated with age, gender, ethnicity and chronic illness for 8 items: dropped many activities and interests, afraid something bad is going to happen, prefer staying home to going out, more problems with memory than most, think it is (not) wonderful to be alive, feel pretty worthless, feel (not) full of energy, feel that situation is hopeless.


CONCLUSIONS
The smaller number of minority Indian and Malay subjects and the self-report of chronic medical illnesses.


CONCLUSIONS
In a heterogeneous mix of respondents in Singapore, eight items of the GDS-15 showed DIF for age, gender, ethnicity and chronic illness. The awareness and identification of DIF in the GDS-15 provides a rational basis for its use in diverse population groups and guiding the derivation of abbreviated scales.
Broekman
B F P
BF
Department of Psychological Medicine, National University of Singapore, Singapore.
Nyunt
S Z
SZ
Niti
M
M
Jin
A Z
AZ
Ko
S M
SM
Kumar
R
R
Fones
C S L
CS
Ng
T P
TP
D000368:Aged; D044466:Asian People / Q000706:statistics & numerical data; D002908:Chronic Disease; D003469:Culture; D003865:Major Depressive Disorder / Q000175:diagnosis* / Q000208:ethnology*; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012720:Severity of Illness Index; D012846:Singapore / Q000453:epidemiology; D012947:Social Work / Q000706:statistics & numerical data