Construct Validity of a New Migraine Satisfaction with Treatment Questionnaire

OBJECTIVES: The aim of this study is to test the content validity of a new questionnaire measuring satisfaction with Treatment in migraine patients, the MISSAT-Q.

METHODS: After thorough scientific literature review and grounded in the SATMED-Q satisfaction model, a total of 35 items were produced to build up the questionnaire. Eight dimensions were defined to structure the questionnaire: Treatment effectiveness in crisis and in prevention, side effects, convenience, impact on Health-Related-Quality-of-Life (HRQoL), monitoring, emotions, and overall satisfaction. An expert panel composed by 3 clinicians, 1 nurse, 3 pharma-economists, 1 expert patient and 1 methodologist supervised item generating process. Thirteen content-specialists in migraine (8 clinicians, 2 nurses, 2 health-outcomes-research specialists and 1 psychologist) valued each of the proposed items in all 8 dimensions defined by the questionnaire (1=measured, 0=unsure, -1=not measured). Item-Domain congruence was measured using the Hambleton-Rovinelli (1976) procedure for assessing item validity by inter-rater agreement.

RESULTS: All items obtained a positive score in the theoretical intended dimension, ranging between 0.52 and 0.92 (88%≥0.70). Most items obtained lower and negative scores in all other dimension. The following pattern was observed: The overall satisfaction dimension tended to obtain low positive scores for most items. Similarly, HRQoL dimension tended to obtain moderate positive scores on most items, particularly for side-effect, prevention and emotion items.

Content-specialists agreed on the assignment of items to their construct dimension as the main measurement dimension. Albeit two dimensions gathered some minor positive values from other theoretic dimension: overall satisfaction, prevention and emotions. This result was expected since the treatment satisfaction construct assumes dimensions to be conceptually correlated.

CONCLUSIONS: Results from the item-Domain congruence task evidence on the validity of most items proposed to measure the Migraine Treatment Satisfaction concept structure, pointing out particular items which may be problematic in further validation steps, like confirmatory factor analysis.