Evaluating the Validity and Reliability of the Beliefs About Medicines Questionnaire in Low-Income, Spanish-Speaking Patients With Diabetes in the United States

Purpose The purpose of this study was to examine the reliability and validity of a Spanish version of the Beliefs about Medicines Questionnaire (BMQ) as a measure to evaluate beliefs about medications and to differentiate adherent from nonadherent patients among low-income Latino patients with diabetes in the United States. Methods Seventy-three patients were administered the BMQ and surveyed for evidence of medication nonadherence. Internal consistency of the BMQ was assessed by Cronbach's alpha along with performing a confirmatory factor analysis. Criterion validity was assessed by comparing mean scores on 3 subscales of the BMQ (General Overuse, General Harm, and Specific NecessityConcerns difference score) between adherent patients and patients reporting nonadherence for 3 different reasons (unintentional nonadherence, cost-related nonadherence, and nonadherence due to reasons other than cost) using independent samples t tests. Results The BMQ is a reliable instrument to examine beliefs about medications in this Spanish-speaking population. Construct validity testing shows nearly identical factor loading as the original construct map. General Overuse scores were significantly more negative for patients reporting each reason for nonadherence compared with their adherent counterparts. Necessity-Concerns difference scores were significantly more negative for patients reporting nonadherence for reasons other than cost compared with those who did not report this reason for nonadherence. Conclusion The Spanish version of the BMQ is appropriate to assess beliefs about medications in Latino patients with type 2 diabetes in the United States and may help identify patients who become nonadherent to medications for reasons other than out-of-pocket costs.