Association of body mass index with symptom severity and quality of life in patients with fibromyalgia

Objective To examine the association between body mass index (BMI) and symptom severity and quality of life (QOL) in patients with fibromyalgia. Methods. We assessed BMI status and its association with symptom severity and QOL in 888 patients with fibromyalgia who were seen in a fibromyalgia treatment program and who completed the Fibromyalgia Impact Questionnaire (FIQ) and the Short Form 36 (SF-36) health survey. Results. The BMI distribution of nonobese (BMI < 25.0 kg/m(2)), overweight (BMI 25.0-29.9 kg/m2), moderately obese (BMI 30.0-34.9 kg/m(2)), and severely obese (BMI > 35.0 kg/m(2)) patients was 28.4% (n = 252), 26.8% (n = 238), 22.2% (n = 197), and 22.6% (n = 201), respectively. Age was significantly different among the 4 groups, with those having a greater BMI being older (P = 0.004). After adjustment for age, group differences were significant in the number of tender points (P = 0.003) and the FIQ and SF-36 scores. The groups with the greater BMI had greater fibromyalgia-related symptoms with worse FIQ total scores (P < 0.001), as well as worse scores in the FIQ subscales of physical function (P < 0.001), work missed (P = 0.04), job ability (P = 0.003), pain (P < 0.001), stiffness (P < 0.001), and depression (P = 0.03). These groups also had poorer SF-36 scores in physical functioning (P < 0.001), pain index (P = 0.005), general health perceptions (P = 0.003), role emotional (P = 0.04), and physical component summary (P < 0.001). Post hoc analysis among the 4 groups showed that differences resided primarily in the severely obese group compared with the other groups. Conclusion. In patients with fibromyalgia, severe obesity (BMI > 35.0 kg/m(2)) is associated with higher levels of fibromyalgia symptoms and lower levels of QOL.