Measurement properties of the Brazilian version of the Kidney Symptom Questionnaire

OBJECTIVE: The aim of this study was to measure the reliability, internal consistency, and construct validity of the Kidney Symptom Questionnaire for the Brazilian population. METHODS: This is a cross-cultural adaptation and questionnaire validation study. We included native Brazilians of both sex aged>18 years, as well as hypertensive and/or diabetic patients. All participants were assessed using Screening for Occult Renal Disease, EuroQol 5 Dimensions, 36-Item Short Form Survey, and the Kidney Symptom Questionnaire. We used Spearman’s coefficient (rho) to measure the correlations between the Kidney Symptom Questionnaire and other instruments; Cronbach’s alpha to measure internal consistency; and intraclass correlation coefficient, standard error of measurement, and minimum detectable change to measure test-retest reliability. RESULTS: The sample was formed by 121 adult participants, mostly female, with systemic arterial hypertension and/or diabetes mellitus. We found excellent reliability (intraclass correlation coefficient≥0.978), adequate internal consistency (Cronbach’s alpha≥0.860), and adequate construct validity on the Kidney Symptom Questionnaire domains; besides, we observed significant correlations between the Kidney Symptom Questionnaire and other instruments. CONCLUSION: The Brazilian version of the Kidney Symptom Questionnaire has adequate measurement properties to assess chronic/occult kidney disease in patients who do not require renal replacement therapy.