Low Body Mass Index Patients Undergoing an Anterior Lumbar Fusion May Have an Increased Risk of Perioperative Complications

Background: Previous research has shown that underweight patients may be at a greater risk of experiencing postsurgical complications. The purpose of this study was to investigate the association between body mass index (BMI) and postoperative complications following single-level anterior lumbar fusion (ALF). Methods: All single-level elective ALF procedures performed between 2010 and 2020 were identified in the PearlDiver Mariner Database. Patients were separated into 6 groups based on the World Health Organization BMI classifications. Differences in postsurgical complications (ie, deep vein thrombosis, pulmonary embolism, surgical site infection, hardware malfunction, wound dehiscence, and blood transfusion) among BMI categories were assessed using a.2 contingency test. Results: Results indicated that underweight patients (BMI <20) were at a significantly greater risk of developing deep vein thromboses, experiencing hardware malfunction, and requiring blood transfusion compared with any other BMI classification (P < 0.001). Results also demonstrated that underweight individuals had similar risks of developing surgical site infection and wound dehiscence compared with patients classified as having obesity class III. Conclusion: Underweight patients may be at a greater risk than currently believed of experiencing postoperative complications following single-level ALF procedures. Clinical Relevance: Patients with a BMI of 20 or less should be carefully evaluated prior to surgical intervention to ensure they are optimized for surgery. Level of Evidence: 3.