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

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.