Development and Internal Validation of a Questionnaire Assessing Predisposition to Nonadherence to Immunosuppressive Medication in Kidney Pretransplant Patients

Abstract

Background. After kidney transplant, nonadherence to immunosuppressive therapy is the main cause of impaired kidney function and graft loss. The objective of this study was the development and internal validation of a clinical questionnaire for assessing the predisposition to adherence to immunosuppressive therapy in kidney pretransplant patients. Methods. Multicenter prospective study conducted in 7 kidney hemodialysis and 6 kidney transplant centers of 3 Brazilian state capitals. Kidney transplant candidate patients of both sexes and >18-y-old were included. Retransplanted patients were excluded. A 72-item pilot version of the questionnaire, created through literature review complemented with a focus group of 8 kidney pretransplant patients, was administered to 541 kidney transplant candidate patients. Factor analysis with varimax rotation was used for questionnaire development. Internal validity evaluation used Cronbach’s alpha and test–retest reliability. Construct validity was assessed by differentiation by known groups. Results. The final questionnaire, named Kidney AlloTransplant Immunosuppressive Therapy Adherence (KATITA) Questionnaire, consisting of 25 items in 3 dimensions, presented good internal consistency reliability (Cronbach’s alpha 0.81). The 3 dimensions and respective Cronbach’s alpha were “Carelessness” (14 items, 0.81), “Skepticism” (6 items, 0.57), and “Concern” (5 items, 0.62). The interdimension correlation matrix showed low correlation coefficients (<0.35). Test–retest reliability, evaluated with 154 patients, showed an intraclass correlation coefficient of 0.62 (moderate agreement). The scale showed construct validity. Conclusions. The KATITA-25 questionnaire is the first psychometric instrument for evaluation of predisposition to nonadherence to immunosuppressive medication in candidate patients for kidney transplant in the pretransplant setting.