Obesity and spine surgery: relation to perioperative complications

Abstract

Object: Many patients undergoing elective thoracic or lumbar fusion procedures are obese, but the contribution of obesity to complications in spine surgery has not been defined. The authors retrospectively assessed the prevalence of obesity in a cohort of patients undergoing thoracic and lumbar fusion and correlate the presence of obesity with the incidence of operative complications. Methods: A retrospective review of consecutive patients treated by a single surgeon (J.K.R.) over a 36-month period at either Rush University Medical Center or the Neurological and Orthopedic Institute of Chicago was performed. The authors identified 332 elective thoracic and lumbar spine surgery cases; the cohort was restricted to include only patients with symptomatic degenerative conditions in need of an anterior, posterior, or combined anterior–posterior fusion. Cases of trauma, tumor, and infection and any case in which the procedure was performed for emergency indications were excluded. A total of 97 cases were identified; of these 86 procedures performed in 84 patients had adequate follow-up material for inclusion in the present study. A broad definition of complications was used. Complications were divided into adverse events (minor) and significant complications (major) based on their impact on patient outcome. Stepwise multivariate logistic regression was used to identify which variables had a significant effect on the risk of complications. Variables considered were body mass index (BMI), height, weight, age, sex, presence or absence of diabetes mellitus (DM) and/or hypertension, number of levels fused (single compared with multiple), and type of surgery performed. The mean BMI for the cohort was 28.8 (95% confidence interval 24.4–30.3); 60 patients (71.4%) were considered overweight or obese (BMI ≥ 25). There were 42 complications in 31 patients (36.9%); this included 19 significant complications in 17 patients (20.2%). Logistic regression revealed that the probability of a significant complication was related to BMI (p < 0.04); the chance of a significant complication was 14% with a BMI of 25, 20% with a BMI of 30, and 36% with a BMI of 40. Positioning-related palsies were only found in extremely obese patients (BMI ≥ 40). The probability of minor complication occurrence increased with age (p < 0.02), not BMI. The rate of complications was independent of sex as well as the presence of DM or hypertension. A standard collection of complications occurred, including wound infection (three cases), cerebrospinal fluid leakage (eight cases, one requiring reoperation), deep vein thrombosis (two cases), cardiac events (four cases), symptomatic pseudarthrosis (one case), pneumonia (three cases), prolonged intubation (two cases), urological issues (eight cases), positioning-related palsy (two cases), and neuropathic pain (two cases). Conclusions: Obesity is a prevalent condition in patients undergoing elective fusion for degenerative spinal conditions and may increase the prevalence and incidence of perioperative complications. In their analysis, the authors correlated increasing BMI and increased risk of significant postoperative complications. The correlation of obesity and perioperative complications may assist in the preoperative evaluation and selection of patients for surgery.