Body mass index and its association with disc degeneration of the lumbar spine in adults

Abstract

INTRODUCTION: Elevated body mass index (BMI) has been suggested as a risk factor of disc degeneration, but such an association remains questionable. Furthermore, the extent and severity of BMI upon disc degeneration remains speculative. As such, we addressed the association of BMI to the presence, extent, and severity of disc degeneration in adults. METHODS: A cross-sectional analysis was performed of 2,252 individuals (range: 21-88 years) of Southern Chinese origin having undergone sagittal T2-weighted MRIs of the lumbar spine. The presence/extent/severity of disc degeneration as well as additional radiographic and subject demographics where assessed. Asian-modified BMI (kg/m2) categories were established. RESULTS: There were 906 males and 1,346 females, with a mean age of 41.4 years. Disc degeneration was noted in 1,598 (71%) subjects. BMI was significantly higher in subjects with disc degeneration (mean: 23.3 kg/m2) compared to subjects without disc degeneration (mean: 21.6 kg/m2) (p<0.001). Age- and workload severity-adjusted BMI was positively correlated with overall disc degeneration severity (r=0.450, p<0.001), the number of levels of disc degeneration (r=0.365, p<0.001), and the overall disc herniation score (r=0.230, p<0.001). In the adjusted logistic regression model, there was a positive and significant polynomial dose-response between BMI and disc degeneration (underweight, 1; normal, OR: 2.3, 95% CI: 1.57-3.23; overweight, OR: 3.2, 95% CI: 2.20-4.73; obese, OR: 5.3, 95% CI: 3.13-9.05; p<0.001) DISCUSSION: Based on the largest population-based study to systematically assess lumbar disc degeneration, our study noted that BMI is associated with the presence of disc degeneration. To our knowledge, our study is the first to note a significantly increasing dose-response between BMI and disc degeneration. Increased extent and severity of disc degeneration was also noted with elevated BMI, in particular overweight and obesity. Future analyses assessing risk factors of disc degeneration should be cognizant of BMI as an influential factor and its effects upon disease.