The Global Activity Limitation Index mainly measured functional disability, whereas self-rated health measured physical morbidity

Abstract Objectives As the Global Activity Limitation Index (GALI) has only recently been created and it is not yet known whether it adds any additional information to self-rated health (SRH), two hypotheses were tested: (1) GALI is primarily correlated with functional disability and secondarily with morbidity and (2) SRH is primarily correlated with morbidity and secondarily with functional disability. Methods The data source used was a subsample of the 2006 Spanish National Health Survey comprising people aged more than 64 years ( N = 7,835). Age, sex, social class, physical and mental morbidities, and functional disability were selected as predictors in multinomial logistic regression models, in which GALI and SRH were the outcome variables. Fractional polynomials were used to handle the continuous predictors. Results The results supported, generally, both hypotheses: functional disability was the main correlate of GALI and physical morbidity, rather than mental morbidity, was the main correlate of SRH. Furthermore, mental morbidity was as strong a correlate of GALI as SRH, but physical morbidity was notably less strong a correlate for GALI than for SRH. Conclusion In older people, GALI mainly measured functional disability, whereas SRH mainly measured physical morbidity.