Background and objective: There are no structural abnormalities in functional dyspepsia, therefore it is essential to have a viable questionnaire to measure treatment outcome according to patient perception. The aim of the study was to extensively document psychometric characteristics of the Glasgow Dyspepsia Severity Score and the Dyspepsia-Related Health Scale that are currently available in Spanish.
Methods: Patients with functional dyspepsia (n = 158) were recruited from a randomized trial that assessed standard vs. standard and psychological treatment. Participants had completed the validation questionnaires and the Medical Outcome Study Short-form 36. Reliability (Cronbach's alpha), validity (Confirmatory Factor Analysis, convergent and known group validity) and responsiveness (minimal clinically important difference) were analyzed.
Results: A Confirmatory Factor Analysis of the Glasgow Dyspepsia Severity Score showed a one-factor solution model, but a low Cronbach's alpha (0.61). With regard to the Dyspepsia-Related Health Scale, the Cronbach's alpha (0.80-0.97) and Confirmatory Factor Analysis supported a model with four inter-correlated dimensions and suggested a need to improve the "Satisfaction with dyspepsia-related health" dimension (Cronbach's alpha < 20). Finally, the global scores for both the Glasgow Dyspepsia Severity Score and the Dyspepsia-Related Health Scale were responsive at six months post-treatment, with a minimal clinically important difference of 4 and 6, respectively.
Conclusions: Our findings support the continued application of the Dyspepsia-Related Health Scale and the need to improve the "Satisfaction with dyspepsia-related health" dimension. Although the Glasgow Dyspepsia Severity Score is a promising questionnaire, further review of the content is required to eliminate and add items in order to provide greater consistency to the evaluated construct.