Fibromyalgia syndrome (FM) is a musculoskeletal pain disorder characterized by chronic widespread pain, hypersensitivity to pain upon palpation, and a range of functional disorders 1 . Although there is controversy regarding the frequency of psychological distress in FM, a majority of investigations suggest that patients with FM have significantly more psychological problems than healthy controls and patients with chronic pain diseases with structural pathology, such as rheumatoid arthritis (RA) 2-8 . The vast majority of patients in the FM literature have been female and in epidemiological studies, women have been shown to be more significantly depressed than men 9 . Psychological factors play an important role in FM 2,10 . However, the psychological status of male patients with FM compared with female patients has not been specifically studied. Our study addresses the issue of gender difference in common and important psychological factors in FM. Based on available literature on gender difference in chronic conditions similar to FM, e.g., headaches and irritable bowel syndrome, we hypothesized that there would be no gender difference in psychological status in FM. MATERIALS AND METHODS Forty men and 160 women with FM were included in the study. All patients fulfilled the 1990 American College of Rheumatology (ACR) criteria for the classification of FM 1 . Male study participants were consecutively seen in the outpatient rheumatology clinic of the University of Illinois College of Medicine at Peoria (UICOMP); female participants, seen in the same clinic during the same period of time (1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002), were randomly selected. Clinical and psychological variables of the patients were assessed by the same protocol in both groups. Duration of disease, education, and tender points (TP) were recorded as continuous variables. A visual analog scale (VAS) was used to evaluate global severity of disease, fatigue, and aches and pains. The items were scored on a 0-100 scale, with 100 denoting the worst possible condition. The severity of pain, sleep disturbance, morning fatigue, anxiety, stress, and depression in the previous month were scored on a 1-4 point scale (1 = none, 2 = mild, 3 = moderate, 4 = severe). These variables were dichotomized as none or mild (no) or moderate and severe (yes) as in our previous studies; the decision for this dichotomization was based on the observation that most symptoms among healthy controls were either none or mild, whereas most symptoms among the patients were either moderate or severe 11 . In addition to measuring psychological variables on ordinal scales 1-4 , they were also assessed by Spielberger State-Trait Anxiety Inventory Scale for anxiety (STAI) 12 , Hassles Scale (HS) for current mental stress 13 , and Zung Self-rating Depression Index (ZSDI) for depression 14 . Health status and physical function were assessed by self-administered Health Assessment Questionnaire (HAQ) STAI contains scales that measure state (SAI) and trait anxiety (TAI). SAI comprises 20 items that assess the intensity of current anxiety symptoms. TAI consists of 20 items and measures the level and symptoms of anxiety across situations over a long-standing period. Scale scores are obtained on a 4-point Likert-type scale and by summing the ratings for scale items. Scores range from 20 to 80 for both, with higher scores indicating higher levels of anxiety ZSDI includes 20 statements; one of the 4 responses is chosen for each statement (1 = none or a little of the time, 2 = some of the time, 3 = good part of the time, 4 = most or all of the time). This scale has been found to Personal, non-commercial use only. The Journal of Rheumatology
