The Brief Medication Questionnaire and Morisky-Green Test to evaluate medication adherence

Abstract

OBJECTIVE: To analyze the reliability and performance of the Portuguese version of questionnaires used to evaluate adherence to hypertensive treatment. METHODS: Hypertensive patients attending a primary healthcare unit in Porto Alegre, Southern Brazil, from January to September 2010, were randomly selected (n = 206). To evaluate adherence, Portuguese versions of the Morisky-Green test (MGT) and the Brief Medication Questionnaire (BMQ) were used. The analysis considered internal consistency, temporal stability and performance compared to three gold standards, which are: inadequate control of blood pressure (BP > 140/90 mmHg); insufficient rate of medication acquisition at the institution's pharmacy (<80%) and a combination of both factors. RESULTS: Of the patients studied, 97 only used medications dispensed by the Basic Health Unit. The tests showed good internal consistency by Cronbach's α: BMQ 0.66 (95%CI 0.60 to 0.73) and the MGT 0.73 (95%CI 0.67 to 0.79). The BMQ Regimen Screen had a sensitivity of 77%, specificity of 58%, and an area under the ROC curve of 0.70 (95%CI 0.55 to 0.86); for MGT sensitivity was 61%, specificity 36% and area under the ROC curve 0.46 (95%CI 0.30 to 0.62). The correlation between the BMQ and the MGT was r=0.28, p> 0.001. Low adherence per the BMQ is associated with higher blood pressure levels when compared to adherent patients (148.4 [SD 20.1] vs 128.8 [SD 17.8]; p <0.001), but not for the MGT. CONCLUSIONS: The BMQ showed better performance than the MGT, with greater sensitivity and specificity. Evaluation of adherence may help clinicians discriminate between inadequate use of medication and insufficient treatment regimen.