Quality of life (QOL) among community dwelling older people in Taiwan measured by the CASP-19, an index to capture QOL in old age

There was no existing scale in Mandarin Chinese to specifically measure QOL in old age. We aimed to validate a Chinese Taiwan version of the CASP-19 (control, autonomy, self-realization, pleasure), a QOL questionnaire, in Taiwan. The existing CASP-19 Cantonese version was modified into Chinese Taiwan version and pilot tested. Data were then gathered from 699 older people. Score distribution, exploratory and confirmatory factor structure, reliability and clinical validity of the CASP-19 and its shortened version, the CASP-12, were examined. The mean age of the participants was 75.5 (standard deviation (SD) 6.5), and half (49.5%) were female. The mean CASP-19 score was 38.2 (range 11-56; SD 7.1), lower than that of Western countries. Exploratory factor analysis revealed an additional factor, 'participation' (CASPP-19). There was satisfactory internal consistency (Cronbach's α 0.63-0.85) for the subscales, except for the control domain. For the 19-item scale, the first order five-domain model (CASPP-19) yielded the best fit. For the CASP-12, first and second order original CASP-12 models performed equally well. There was an inverse relationship between the CASP total scores and frailty, chronic diseases, depressive disorders, living alone and fall events in the past 12months, supporting good clinical validity for all versions of the CASP scale (CASP-19, CASPP-19, original and new CASP-12). The original CASP-12 may be presently the best choice for use in China, Taiwan or other Mandarin-speaking populations due to its conciseness and model parsimony.