Measuring treatment satisfaction in MS: Is the treatment satisfaction questionnaire for medication fit for purpose?

Background: The Treatment Satisfaction Questionnaire for Medication (TSQM) was designed to assess patient treatment satisfaction in chronic diseases. Its performance has not been examined in multiple sclerosis (MS). The 14 items of the TSQM cover four domains: Effectiveness, Side Effects, Convenience, and Global Satisfaction. Objective: To evaluate performance of the TSQM in patients with relapsing MS, using data collected from the TENERE study (NCT00883337), in which 324 patients received oral teriflunomide or subcutaneous interferon beta-1a for ≥48 weeks. Methods: Five measurement properties were examined using traditional psychometric methods: data completeness, scale-to-sample targeting, scaling assumptions, reliability (including test-retest), and construct validity (internal: item-level scaling success, confirmatory factor analysis, and exploratory factor analysis; external: convergence, discrimination, and group differences). Results: There were few (<2%) missing item data; domain scores could be computed for all patients. Score distributions were skewed toward higher satisfaction; two domains had marked ceiling effects. Scaling assumptions were supported. Internal consistency reliability was high (Cronbach's α > 0.90). Internal validity tests supported item groupings. Correlations supported convergent and discriminant construct validity; hypothesis testing supported group differences validity. Conclusion: This investigation found the TSQM to be a useful tool, exhibiting good psychometric measurement properties in patients with relapsing MS in the TENERE study.