Body Mass Index and Risk for Clinical Lumbar Spinal Stenosis

Authors: Björn Knutsson, MD

Spine. 2015;40(18):1451-1456.

Study Design. A prospective cohort study that used a Swedish nationwide occupational surveillance program for construction workers (period of registration from 1971 to 1992). In all, 364,467 participants (mean age at baseline 34 yr) were included in the study.

Objective. To determine whether overweight and obesity are associated with a higher risk of lumbar spinal stenosis (LSS).

Summary of Background Data. During recent decades, LSS has become the most common indication for spine surgery, a change that coincides with a higher prevalence of obesity.

Methods. A diagnosis of LSS was collected through individual linkage to the Swedish National Patient Register through December 31, 2011. Poisson regression models were employed to estimate multivariable-adjusted incidence rate ratios (IRRs) for LSS.

Results. At baseline, 65% had normal weight (BMI [body mass index]: 18.5–24.99 kg/m²), 29% were overweight (BMI: 25–29.99 kg/m²), 5% were obese (BMI ≥30 kg/m²), and 2% were underweight (BMI <18.5 kg/m²). During 11,190,944 person-years of follow-up, with a mean of 31 years, 2381 participants were diagnosed with LSS. Compared with normal weight individuals, obese workers had an IRR of 2.18 (95% confidence interval, 1.87–2.53) for LSS and overweight workers had an IRR of 1.68 (95% confidence interval, 1.54–1.83). Workers who were underweight halved their risk of LSS (IRR: 0.52, 95% confidence interval, 0.30–0.90).

Conclusion. Obese and overweight persons are at a higher risk of developing LSS. Furthermore, our results indicate that obesity might be a novel explanation for the increased number of patients with clinical LSS.