E.ABDIN1, S.A. CHONG1, E.SEOW1, J.H. LAU1, V.SEET1, J.A.VAINGANKAR1, M.SUBRAMANIAM1
Institute of Mental Health1
The aim of the current analysis was to validate the 12-item World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0) as a generic instrument for measuring functioning and disability in patients with schizophrenia in Singapore.
A total of 189 outpatients with schizophrenia were recruited and administered the 12-item WHODAS 2.0, and the Social and Occupational Functioning Assessment Scale (SOFAS) for assessing current functioning, Montreal Cognitive Assessment (MoCA) for the assessment of cognitive impairment and Positive and Negative Syndrome Scale for rating symptom severity. A series of confirmatory factor analyses (CFA) were conducted to examine the structural validity of the WHODAS 2.0. The internal consistency reliability, convergent validity, and test-retest validity were tested using Cronbach’s alpha, Pearson correlation, and intraclass correlation coefficients.
CFA confirmed one-factor model structure of the 12-item WHODAS 2.0. The instrument demonstrated high internal consistency (Cronbach’s alpha=0.91) and adequate construct validity. The correlation between the 12-item WHODAS 2.0, SOFAS and the MoCA were inversely significant and ranged from -0.15 (MoCA) to -0.41 (SOFAS). While the correlation coefficient between the 12-item WHODAS 2.0 and PANSS subscales were positively significant and ranged from 0.18 (PANSS negative) to 0.41 (PANSS general psychopathology), respectively. The agreement between self-administered and interviewer-administered mode, estimated based on an intraclass correlation coefficient seems to be good (0.80, 95% CI: 0.63-0.90).
WHODAS 2.0 was found to be a valid generic measure of functional disability among patients with schizophrenia in Singapore.