Cut-off Value for Body Mass Index in Predicting Surgical Success in Patients with Lumbar Spinal Canal Stenosis

Parisa Azimi; Taravat Yazdanian; Sohrab Shahzadi; Edward C Benzel; Shirzad Azhari; Hossein Nayeb Aghaei; Ali Montazeri

doi:10.31616/asj.2018.12.6.1085

Cut-off Value for Body Mass Index in Predicting Surgical Success in Patients with Lumbar Spinal Canal Stenosis

Asian Spine J. 2018 Dec;12(6):1085-1091. doi: 10.31616/asj.2018.12.6.1085. Epub 2018 Oct 16.

Authors

Parisa Azimi¹, Taravat Yazdanian², Sohrab Shahzadi¹, Edward C Benzel³, Shirzad Azhari¹, Hossein Nayeb Aghaei¹, Ali Montazeri⁴

Affiliations

¹ Functional Neurosurgery Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
² School of Medicine, Capital Medical University, Beijing, China.
³ Department of Neurosurgery, Cleveland Clinic Foundation, Cleveland, OH, USA.
⁴ Mental Health Research Group, Health Metrics Research Centre, Iranian Institute for Health Sciences Research, Academic Center for Education, Culture and Research, Tehran, Iran.

Abstract

Study design: Case-control.

Purpose: To determine optimal cut-off value for body mass index (BMI) in predicting surgical success in patients with lumbar spinal canal stenosis (LSCS).

Overview of literature: BMI is an essential variable in the assessment of patients with LSCS.

Methods: We conducted a prospective study with obese and non-obese LSCS surgical patients and analyzed data on age, sex, duration of symptoms, walking distance, morphologic grade of stenosis, BMI, postoperative complications, and functional disability. Obesity was defined as BMI of ≥30 kg/m2. Patients completed the Oswestry Disability Index (ODI) questionnaire before surgery and 2 years after surgery. Surgical success was defined as ≥30% improvement from the baseline ODI score. Receiver operating characteristic (ROC) analysis was used to estimate the optimal cut-off values of BMI to predict surgical success. In addition, correlation was assessed between BMI and stenosis grade based on morphology as defined by Schizas and colleague in total, 189 patients were eligible to enter the study.

Results: Mean age of patients was 61.5±9.6 years. Mean follow-up was 36±12 months. Most patients (88.4%) were classified with grades C (severe stenosis) and D (extreme stenosis). Post-surgical success was 85.7% at the 2-year follow-up. A weak correlation was observed between morphologic grade of stenosis and BMI. Rates of postoperative complications were similar between patients who were obese and those who were non-obese. Both cohorts had similar degree of improvement in the ODI at the 2-year followup. However, patients who were non-obese presented significantly higher surgical success than those who were obese. In ROC curve analysis, a cut-off value of ≤29.1 kg/m2 for BMI in patients with LSCS was suggestive of surgical success, with 81.1% sensitivity and 82.2% specificity (area under the curve, 0.857; 95% confidence interval, 0.788-0.927).

Conclusion: This study showed that the BMI can be considered a parameter for predicting surgical success in patients with LSCS and can be useful in clinical practice.

Keywords: Body mass index; Lumbar spinal stenosis; Predicting; ROC curve; Surgical success.