Cross-cultural adaptation of the Independence in activities of daily living index (Katz index)

This study involved the development and performance assessment of a cultural adaptation of the Katz scale of independence in activities of daily living, translated into Portuguese in Brazil. Two translations and two back-translations of the items were analyzed by experts in order to decide on the final version. Operational equivalence was assessed in a pilot study. The reliability and internal consistency of the adapted version were assessed by retesting 156 patients on the same day or 7 days after the first interview. Cultural equivalence was achieved after resolving subtle differences in some items. The final version was considered easy to understand and use. Chance-corrected agreement (weighted kappa) was 0.91. Cronbach's alpha ranged from 0.80 to 0.92. Conclusions: a Portuguese version of the Katz scale of independence in activities of daily living, thoroughly developed and tested, proved equivalent to the original version in English. The items were internally consistent and the rates were reliable.