The Health Assessment Questionnaire (Fries et al., 1982) was used to assess functional capacity, namely the Portuguese version of the questionnaire which was validated for the portuguese population (Santos et al., 1996). It is a 20-item questionnaire covering activities of daily living in 8 domains: dressing, arising, eating, walking, hygiene, reach, grip, errands and chores. Every question can be answered on a four-level scale regarding patient’s ability to perform an activity of daily living (0, no difficulty; 1, some difficulty; 2, much difficulty; 3, unable). Scores between 0 and 1 are generally considered to represent mild to moderate difficulty; between 1 and 2, moderate to severe disability; and between 2 and 3, severe to very severe disability.
Fries, J., Spitz, P., & Young, D. (1982). The dimensions of health outcomes: the health assessment questionnaire, disability and pain scales. Journal of Rheumatology, 9(5), 789–793.
Santos, R., Reis, P., Rebelo, L., Dias, F., Rosa, C., & Queiroz, M. (1996). Health Assessment Questionnaire (versão curta): adaptação para a língua portuguesa e estudo de aplicabilidade. Acta Reumatológica Portuguesa, 21(76), 15–20.