Cross-cultural adaptation of the Karnofsky Performance Status instrument to Brazilian Portuguese

The Karnofsky Performance Status (KPS) is one of the most widely used tools for assessing the prognosis of oncology patients, providing an estimate of treatment efficiency and survival. Despite this, it is commonly used in free translations without validation. The objective of the present study was to perform the cross-cultural adaptation of the KPS instrument to Brazilian Portuguese (KPS-BR) through the stages of conceptual, semantic, operational, measurement, and functional equivalences. To assess consistency, we used Cronbach's alpha and kappa coefficients. The Chi-square test was performed to evaluate the association between scores and the number of deaths. The relationship with survival and mortality was explored with Kaplan-Meier curves. A total of 316 patients participated in the study. The internal consistency analysis resulted in a Cronbach's alpha coefficient of 0.9265. For the inter-rater analysis, the correlation coefficient was 1, as was the kappa coefficient, indicating perfect agreement between observers. The correlation coefficient between the KPS-BR scale in the test-retest was 0.8631. We observed a 100% death rate at KPS-BR scale score 20 and a gradual decrease as the KPS-BR scale score increases up to KPS-BR 40 (p