Desenvolvimento e validação de um questionário clínico para avaliação da predisposição a adesão ao tratamento imunossupressor em pacientes do pré-transplante renal

Abstract

Introduction: Nonadherence to immunosuppressive therapy after kidney transplantation is a critical factor leading to rejection and graft loss. Identifying nonadherence immunosuppressants is essential for effective treatment, however, it often occurs after irreparable damage to the graft has already been done. Therefore, the prior identification of patients susceptible to this nonadherence would enable the adoption of preventive measures. However, clinical instruments have not yet been developed for this purpose. Objective: To develop and validate a psychometric scale for the assessing the propensity for nonadherence to immunosuppressant therapy in pre-kidney transplant patients. Methodology: Multicenter, prospective, observational, cross-sectional, longitudinal and analytical study in candidate patients for kidney transplant of both sexes, over 18 years old. To develop the psychometric scale, a set of items expressing patient statements were compiled, obtained through a literature review, focus group and an expert panel. The pilot questionnaire was administered to 541 patients from 13 healthcare centers, of which 154 repeated the questionnaire approximately 12 months later. The final questionnaire was obtained by exploratory factor analysis and internal validation included analysis of internal consistency reliability, test-retest reliability and convergent validity assessed by differentiation by known groups. For external validation, 381 patients with already scheduled surgery were included in six transplant centers and were observed in the pre-transplant and in months 3, 6 and 12 post-transplant for evaluation of criterion validity, by comparison with two medication nonadherence scales, and validity predictive of nonadherence, assessed by a combination of 3 methods (self-report, serum level of immunosuppressants and drug withdrawal from the pharmacy). For cross-cultural validation of the Spanish version, the scale was administered to 163 patients over 18 years-old, of both sexes, candidates for kidney transplantation, recruited from 2 kidney transplant centers and 2 dialysis centers in Catalonia, Spain. The scale was re-administered to the first 79 patients included into the study, after an interval of 2 to 4 weeks. Internal consistency reliability was assessed with Cronbach's alpha and test-retest reliability with the intraclass correlation coefficient (ICC); construct validity was assessed with confirmatory factor analysis using structural equation modeling. Results: The final questionnaire, called Kidney AlloTransplant Immunosuppressive Therapy Adherence (KATITA) Questionnaire, consisting of 25 items in 3 uncorrelated dimensions, showed 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). Test-retest reliability showed an intraclass correlation coefficient of 0.62 (moderate agreement). The scale showed convergent validity. The longitudinal study included 381 patients and confirmed the multidimensional structure of the scale and criterion validity. The predictive validity of the scale was confirmed by an area under the ROC curve of 0.68, sensitivity of 59,8%, specificity of 68,2%, and positive predictive value of 71,8%. The Cronbach's alpha of the Spanish version was 0.83, and the alphas of the 3 subscales were 0.82, 0.74, and 0.52. In test-retest reliability analysis, the ICC was 0.86. Confirmatory factor analysis showed adequate fit of the structural model. In general, the analytical results were similar to those obtained in the validation of the original scale. Conclusion: The KATITA-25 questionnaire is the first validated psychometric questionnaire assessing predisposition to nonadherence to immunosuppressive medication in candidate patients to kidney transplantation in the pre-kidney transplant setting.