Beliefs about medications: measurement and relationship to adherence in patients with severe mental disorders

Objective: To determine if the Beliefs about Medicines Questionnaire (BMQ) has satisfactory psychometric properties in patients with severe mental disorders and if their scores differ from those of patients with severe medical disorders. To investigate if the scores are related to medication adherence. Method: Two hundred and eighty psychiatric patients completed the BMQ and reported how much of their medication they had taken the past week. Serum concentrations of medications were analyzed. BMQ scores were compared with those of patients with chronic medical disorders. Results: Cronbach's alpha was satisfactory for all subscales. The psychiatric group scored lower on the necessity of taking medication than the medical group. Non-adherent patients felt medication to be less necessary and were more concerned about it than adherent patients. The necessity subscale predicted adherence fairly well. Conclusion: The BMQ has satisfactory psychometric properties for use in patients with severe mental disorders. The constructs measured by the BMQ are related to adherence in these patients.