Association of body mass index and fibromyalgia symptom severity by gender

We evaluated the relationship between body mass index (BMI) and fibromyalgia (FM) symptom severity in 10,651 men and women with FM seen at a tertiary medical center who responded to a mailed survey that included demographics, height, weight, and the modified 2010 American College of Rheumatology (ACR) FM Criteria. Respondents were grouped into World Health Organization (WHO) BMI categories. Analysis of variance (ANOVA) and multiple pairwise comparisons with Fisher's least significant differences test were conducted between BMI and fibromyalgia symptoms (FS) for all respondents and separately for men and women. Of survey respondents (n=2499), 93% were female with a mean age of 56.8 ±13.3 years. BMI distribution of normal, overweight, moderately obese, severely obese, and extremely obese was 29.8%, 29.3%, 20.7%, 12.0%, and 8.2% for the whole sample; 23.9%, 38%, 25.1%, 8.1%, and 4.6% for males; 30.3 %, 28.6%, 20.3%, 12.2%, and 8.4% for females, respectively. Since differences in FS scores were not observed between normal and overweight, the two categories were combined into one group (Group A). Similarly, moderately, severely, and extremely obese were combined into a second group (Group B). Significant differences in FS between Group A and B were found for the sample as a whole (p<0.001) and for men (p<0.05) and women (p<0.001) separately. Our results indicate that BMI is related to fibromyalgia symptom severity in both men and women. To our knowledge, this is the first report assessing the association between BMI and fibromyalgia symptom severity by gender.