Reliability and component structure of the modified Daily Symptom Report (DSR-20)

Abstract Objectives The purpose of the present study was to modify Freeman et al.'s (1996) Daily Symptom Report (DSR) for premenstrual syndrome (PMS) by adding items depicting aggressive and impulsive symptoms, to explore the component structure of this revised measure (DSR-20) in a sample of PMS sufferers, and to compare their scores with those from controls during the follicular and luteal cycle phases. Methods The DSR-20 was administered to 140 PMS sufferers who were seeking treatment for PMS and 54 controls who considered themselves to be free from premenstrual complaints daily for three menstrual cycles. Results Cronbach's α was 0.95 for the luteal DSR-20 scores of the PMS sufferers, indicating very high internal consistency of the 20 items. Exploratory Principal Components Analysis (PCA) of the luteal ratings of the PMS sufferers identified two components with high internal consistency (> 0.90), describing psychological and physical premenstrual symptoms. PMS sufferers scored significantly higher than the controls on each of these components during the luteal, but not follicular, phase. Conclusions The DSR-20 total scale score is an internally consistent global measure of the intensity of PMS. The division of PMS symptoms into psychological and physical components, both of which significantly differentiated PMS sufferers from controls during the luteal phase, sheds further light on the description of PMS and provides a clinically relevant and practical means by which to summarise and interpret daily symptom ratings, necessary for the identification and investigation of the syndrome.