Psychometric validation of the dysmenorrhea daily diary (DysDD): a patient-reported outcome for dysmenorrhea

Abstract

The objective of this study was to evaluate the psychometric properties of the Dysmenorrhea Daily Diary (DysDD), an electronic patient-reported outcome, in a sample of 355 women with primary dysmenorrhea enrolled in a phase IIb, multicenter, randomized, partially blinded, placebo-controlled trial for treatment of dysmenorrhea. Subjects completed the DysDD over three menstrual cycles, one pre-treatment baseline cycle and two treatment cycles. The DysDD was administered alongside the Menstrual Distress Questionnaire (MDQ), the Short-Form 36 Version 2.0 (SF-36v2), and a Global Assessment of Change (GAC). Item response distributions, test-retest reliability, concurrent and known groups validity, responsiveness, and minimally important difference (MID) were evaluated for the DysDD. As expected, item response distributions varied throughout the menstrual period for all items, with the response scales fully utilized. Within-cycle test-retest reliability was adequate (weighted kappa: 0.5-0.7), although between-cycle test-retest was poor (weighted kappa: 0.1-0.5), most likely due to the highly variable nature of dysmenorrhea between cycles rather than limitations of the measure. Correlations with the MDQ and SF-36v2 were low-moderate, but in the predicted direction, supporting concurrent validity. There were significant differences in DysDD scores across severity groups based on pain medication use. The DysDD was responsive to changes in patients' dysmenorrhea with significantly different changes in scores between change groups (p < 0.0001). MID analyses suggest changes on the DysDD 0-10 pelvic pain score of three points can be considered clinically meaningful. Overall, findings indicate that the DysDD has acceptable reliability and is a valid and responsive instrument for assessing dysmenorrhea.