Adaptation and validation of an oral anticoagulation measurement of treatment adherence instrument.

This methodological study adapted and analyzed the psychometric properties of the Measurement of Treatment Adherence (MTA) instrument for Brazilian users of oral anticoagulation therapy. Its final version was tested with 178 individuals. The average of answers for all questions ranged from 4.6 to 5.8 and 97.2% of the individuals were considered adherent. Moderate correlations were obtained between the adherence measure and the Mental health and Vitality domains of the SF-36. Cronbach's alpha was 0.60 and the ceiling effect occurred in answers to all items. These results indicate weak evidence of the validity, reliability and responsiveness of the MTA-adapted version for users of oral anticoagulant therapy.