Association between obesity and functional status in patients with spine disease

Study Design. A cross-sectional study of 15,974 patients with spine disease from 26 members of the National Spine Network. Objectives. To use functional status measures and clinical parameters to evaluate the association between obesity and health status among patients with spine conditions. Summary of Background Data. With 22.5% of Americans overweight, obesity is a significant health concern. However, the functional impact caused by obesity in spine patients remains unknown. Methods. Functional status was measured on 15,974 patients on an initial visit using a general physical health measure (SF-36 Physical Component Summary score) and a disease-specific measure (Oswestry Disability Index). Obesity was measured using body mass index (kg/m(2)), Patients were categorized into four groups according to body mass index: normal range (<25.0 kg/m(2), n = 5732), Grade 1 obesity (25.0-29.9 kg/m(2), n = 5845), Grade 2 obesity (30.0-39.9 kg/m(2), n = 3836), and Grade 3 obesity (greater than or equal to40.0 kg/m(2), n = 561). The associations between SF-36 Physical Component Summary and Oswestry Disability Index scores and body mass index were evaluated in a multivariate linear regression model. Clinical presentation data were derived from patient and clinician reports and were compared across body mass index categories. Results. In the four obesity categories, the PCS scores were 32.6 (normal range body mass index), 30.8 (Grade 1), 28.2 (Grade 2), and 25.9 (Grade 3) (P < 0.001). The SF-36 Physical Component Summary score of the general U.S. population is 50.0. The Oswestry Disability Index scores across the four body mass index groups were 39.0, 41.6, 46.6, and 52.2, respectively (P < 0.001). Compared with nonobese patients, obese patients were more likely to have radicular pain and neurologic signs (P < 0.01). Furthermore, obese patients had more comorbidities and were more likely to be receiving worker's compensation. After adjusting for clinical and demographic factors, each increased level of obesity was associated with a 1-1.5point worsening in both the SF-36 Physical Component Summary and Oswestry Disability Index scales (P < 0.05). Conclusions. General and disease-specific functional health status was significantly worse for patients with a higher body mass index. Obese patients also displayed more severe pain symptoms than nonobese spine patients.