Beliefs About Medicines in Patients with Hypertension: The Instrument Validity and Reliability in Iran

Abstract

PURPOSE: Despite the importance of patients believes as one of the most important predictors of treatment adherence behavior, it is rarely considered in numerous studies. Then the current survey was aimed to develop and study the beliefs about medicines questionnaire (BMQ) in patients with hypertension. MATERIALS AND METHODS: The BMQ developed by Horn and et al. was used in the current study. This questionnaire included 18 questions in both public and private beliefs regarding drug. Face and content validity of the tool was investigated using expert's panel. In final, aforementioned tool was tested in 612 participants. To explore structure validity and internal consistency, exploratory and confirmatory factor analysis and alpha coefficient was conducted. To evaluate the final validity of instrument, the mean score of the beliefs about medicines of patients with appropriate medication adherence were compared to patients without medication adherence. RESULTS: The mean age of patients was 44.08 +/- 10.38 years. Women were 314 of participants. Calculated face validity by the impact score for each item indicated that all the items of the questionnaire had the impact score of more than 1.5. In total, all items had scored higher than 0.79 by considering 18 items for content validity. The average of content validity index for the questionnaire was 0.93. Load of factors were in the range of 0.51 to 0.79. Four items explained 57 of the total variance. Comparison of all instrument items in the two groups showed that patients with good adherence had higher score in 15 items ( 83 of all items). CONCLUSION: The findings suggested that the BMQ in patients with hypertension as a valid and reliable instrument can be used to evaluate the patients' medication adherence.