The purpose of this study is to assess the psychometric properties of the Portuguese version of the Control, Autonomy, Self-realization, and Pleasure (CASP)-12 scale used in the Survey of Health, Aging and Retirement in Europe (SHARE) project. Data were obtained from a representative sample of 1666 people aged ≥50 years living in Portugal and participating in the SHARE wave 6. In addition to the CASP-12 scale, sociodemographic data and health status, activity limitation (GALI), depression (Euro-D) and satisfaction with life scores were collected. Data quality and acceptability, construct and structural validity and internal consistency of the CASP-12 scale were analyzed. A Rasch analysis was also performed. CASP-12 total score (mean: 33.3; standard deviation: 5.8, range: 12-48) correlated with Euro-D (-0.57) and with life satisfaction (0.52). Mean scores were significantly lower for women, people aged ≥75 years and those with activity limitations and worse health status (p < 0.001). The confirmatory factor analysis showed good fit to the 4-factor model (root mean squared error of approximation (RMSEA): 0.07; comparative fit index (CFI): 0.90, χ2 (48) = 444.59, p < 0.001), which was confirmed by Rasch analysis (χ2 (36) = 10.089, p = 0.745, person separation index (PSI) = 0.722 for the 4-factor model). For domains, person separation index ranged 0.31-0.79 and Cronbach's alpha, 0.37-0.73. In conclusion, the Portuguese version of the CASP-12 scale presents some inadequacies in acceptability, internal consistency and structural validity.
Keywords: CASP-12; Portugal; Rasch model; older adults; quality of life.