Does Patient Body Mass Index Affect the Outcome of Multimodal Rehabilitation in Chronic Mechanical Low Back Pain?

STUDY DESIGN: Retrospective. OBJECTIVE: The aim of this study was to investigate the effect of body mass index (BMI) on pain and disability in patients with chronic mechanical low back pain (LBP) treated with multimodal rehabilitation. SUMMARY OF BACKGROUND DATA: Despite being a well-known risk factor for developing LBP, there is minimal data on the effect of BMI on pain and disability in patients with chronic mechanical low back pain (LBP) treated with multimodal rehabilitation. METHODS: Data from patients with chronic mechanical LBP who underwent multimodal rehabilitation treatment at a chain of spine rehabilitation outpatient clinics in one of the three BMI groups-1564 patients in normal body weight (BMI ≥18.5-24.9), 1990 patients in overweight (BMI ≥25-29.9), and 891 patients in obese (BMI ≥ 30) groups-were retrospectively analyzed. Pre- and post-treatment Numerical Pain Rating Scale (NPRS) and Oswestry Disability Index (ODI) scores, and final treatment outcomes were compared between the three groups. Multivariate analysis was used to determine the association between pre-treatment covariates and post-treatment clinical outcomes. RESULTS: Post-treatment, the mean NPRS (P = 0.005) and mean ODI (P < 0.001) scores were significantly higher with a significantly lower percentage of full success outcome (P = 0.009) in the obese group when compared to normal and overweight groups. However, multivariate analysis showed a significant correlation between age, the number of treatment sessions, pre-treatment NPRS and ODI scores, and post-treatment NPRS and ODI scores and treatment failure, and no correlation with patient BMI. CONCLUSION: Patient BMI may not affect pain and disability outcomes in patients undergoing a multimodal rehabilitation treatment for chronic LBP. In contrast to BMI, other covariates such as age, treatment sessions, and pre-treatment NPRS and ODI scores may be associated with increased risk for poor treatment outcome. Obese individuals can expect clinical outcomes similar to normal or overweight individuals with multimodal physical rehabilitation for chronic LBP.Level of Evidence: 3.