Bariatric surgery before elective posterior lumbar fusion is associated with reduced medical complications and infection

Background context: Severely obese patients with operative spinal pathology present a challenge to the spine surgeon, given the increased complication risk. Purpose: We aimed to determine the impact of bariatric surgery (BS) on perioperative complications of posterior lumbar fusion. Study Design: This is a retrospective cohort study. Patient Sample: Patients undergoing posterior lumbar fusion surgery in the State Inpatient Databases of New York, Florida, North Carolina, Nebraska, Utah, and California comprised the patient sample. Outcomes: Thirty-day medical complications, surgical complications (nerve injury, infection, revision), death, readmission, and hospital length of stay (LOS) were the study's outcomes. Methods: We analyzed 156,517 patients using International Classification of Diseases, Ninth Revision codes. Patients were categorized into three groups: Group 1: history of BS and obesity, Group 2: severe obesity, body mass index (BMI)>40 (severely obese), and Group 3: normal weight, BMI<25 (non-obese). Logistic and linear multivariate regressions were performed to compare complications and LOS, respectively, between BS and severely obese groups and BS and non-obese groups while controlling for confounders. There were no sources of funding for this study. Results: There were 590 patients with BS, 5,791 severely obese, and 150,136 non-obese. Comparing BS with severely obese, BS had significantly lower rates of respiratory failure (odds ratio [OR] 0.59, p=.019), urinary tract infection (OR 0.64, p=.031), acute renal failure (OR 0.39, p=.007), overall medical complications (OR 0.59, p<.001), and infection (OR 0.65, p=.025). Bariatric surgery also had significantly lower hospital LOS (B=−0.46, p=.01). Comparing BS with non-obese, there were no significant differences in medical complications; however, BS had significantly higher rates of infection (OR 2.70, p<.001), reoperation (OR 2.05, p=.045), and readmission (OR 1.89, p<.001). Conclusion: Bariatric surgery before elective posterior lumbar fusion mitigates risk of medical complications and infection. However, these patients still have increased risk of infection, revision surgery, and readmission compared with patients with normal BMI. Surgeons might consider referral for BS for the severely obese patient before undergoing spine surgery.