title: Measuring disability across cultures--the psychometric properties of the WHODAS II in older people from seven low- and middle-income countries. The 10/66 Dementia Research Group population-based survey.
abstract: We evaluated the psychometric properties of the 12-item interviewer-administered screener version of the World Health Organization Disability Assessment Schedule-version II (WHODAS II) among older people living in seven low- and middle-income countries. Principal component analysis (PCA), confirmatory factor analysis (CFA) and Mokken analyses were carried out to test for unidimensionality, hierarchical structure, and measurement invariance across 10/66 Dementia Research Group sites. PCA generated a one-factor solution in most sites. In CFA, the two-factor solution generated in Dominican Republic fitted better for all sites other than rural China. The two factors were not easily interpretable, and may have been an artefact of differing item difficulties. Strong internal consistency and high factor loadings for the one-factor solution supported unidimensionality. Furthermore, the WHODAS II was found to be a 'strong' Mokken scale. Measurement invariance was supported by the similarity of factor loadings across sites, and by the high between-site correlations in item difficulties. The Mokken results strongly support that the WHODAS II 12-item screener is a unidimensional and hierarchical scale confirming to item response theory (IRT) principles, at least at the monotone homogeneity model level. More work is needed to assess the generalizability of our findings to different populations.
authors.affiliation: Institute of Psychiatry, King's College London, Health Services & Population Research Department, London, UK. r.sousa@iop.kcl.ac.uk
authors.forename: Renata M
authors.initials: RM
authors.lastname: Sousa
authors.forename: Michael E
authors.initials: ME
authors.lastname: Dewey
authors.forename: Daisy
authors.initials: D
authors.lastname: Acosta
authors.forename: A T
authors.initials: AT
authors.lastname: Jotheeswaran
authors.forename: Erico
authors.initials: E
authors.lastname: Castro-Costa
authors.forename: Cleusa P
authors.initials: CP
authors.lastname: Ferri
authors.forename: Mariella
authors.initials: M
authors.lastname: Guerra
authors.forename: Yueqin
authors.initials: Y
authors.lastname: Huang
authors.forename: K S
authors.initials: KS
authors.lastname: Jacob
authors.forename: Juana Guillermina
authors.initials: JG
authors.lastname: Rodriguez Pichardo
authors.forename: Nayeli
authors.initials: N
authors.lastname: Garcia Ramírez
authors.forename: Juan
authors.initials: J
authors.lastname: Llibre Rodriguez
authors.forename: Marina
authors.initials: M
authors.lastname: Calvo Rodriguez
authors.forename: Aquiles
authors.initials: A
authors.lastname: Salas
authors.forename: Ana Luisa
authors.initials: AL
authors.lastname: Sosa
authors.forename: Joseph
authors.initials: J
authors.lastname: Williams
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Prince
mesh_terms: D000203:Activities of Daily Living / Q000523:psychology; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000523:psychology*; D002681:China; D003431:Cross-Cultural Comparison; D003704:Dementia / Q000175:diagnosis* / Q000523:psychology; D003906:Developing Countries / Q000191:economics; D004185:Disability Evaluation; D006233:Persons with Disabilities / Q000145:classification / Q000523:psychology*; D004293:Dominican Republic; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000706:statistics & numerical data*; D025341:Principal Component Analysis; D011569:Psychiatric Status Rating Scales; D011594:Psychometrics / Q000706:statistics & numerical data; D015203:Reproducibility of Results; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires; D014944:World Health Organization