Introduction and aim: Transplant recipients are chronically ill patients who rely on medical treatment throughout life to achieve positive results. Despite that, medication nonadherence after liver transplantation is extremely common. The self-report, one of several methods for measuring adherence, is easy to apply and low cost. Thus, this study aims to translate and validate the Immunosuppressant Therapy Adherence Instrument (ITAS) in Brazilian Portuguese for liver transplant recipients.
Material and methods: A total of 139 liver transplant recipients were selected from a general hospital, who were assessed by using the Portuguese version of ITAS. The scale was translated based on the model proposed by Wild, et al. and its psychometric properties were assessed.
Results: The average Cronbach's α coefficient was 0.830. ITAS and Basel Assessment of Adherence with Immunosuppressive Medications Scale (BAASIS) presented significant correlation, with a Spearman's ρ coefficient = 0.300 (S = 309,580; p < 0.001). The area under the receiver operating characteristics (ROC) curve was 0.638 (95% CI: 0.557 - 0.715). Factor analysis results indicated that the carelessness factor model was the optimal model, and the factor "feeling worse" was the lowest.
Conclusion: The Portuguese version of ITAS has adequate psychometric properties to measure adherence to immunosuppressant therapy.
Keywords: Adherence. Liver Transplantation. Immunosuppression. Psychometrics..