Factor structure of the modified Moos Menstrual Distress Questionnaire: assessment of prospectively reported follicular, menstrual and premenstrual symptomatology.

Despite the wide usage of the Moos Menstrual Distress Questionnaire (MDQ) in menstrual cycle research, the factor structure of the questionnaire has received relatively little attention since derived by Moos in 1968. This issue is one of considerable importance given that the methods of data collection used by Moos have since been subject to serious criticism. The aim of the current study was to determine whether Moos' factors could be replicated based on daily and prospective completion of the MDQ in women who were unaware of the study aims. One hundred and eighty-seven women from the general community (mean age 30 years) completed a modified version of the MDQ daily for 70 days. Principal components analysis of the modified MDQ items during the follicular, late luteal and menstrual phases indicated that a six-factor solution similar to that derived by Moos best summarized the data. A number of symptoms, however, loaded highly on more than one factor. This created some instability in the solution and may explain the discrepancies in previous research. Nonetheless, it was concluded that the Moos factors effectively represent the structure of menstrual cycle symptoms.