Impact of obesity on complications and patient-reported outcomes in adult spinal deformity surgery

Abstract

Background Adult spinal deformity (ASD) surgery is known for its high complication rate. Obesity is known to be a risk factor for increased complications in orthopedic procedures, but its specific effect in adult spinal deformity (ASD) surgery is not well understood. This study looks at the impact of obesity on complications and HRQOL in adult spinal deformity surgery. Methods Retrospective review of a multicenter prospective database of operative ASD patients. Obesity was defined by a BMI &#8805 + 30. Outcomes included complications (total, minor, major, implant related, radiographic, infection, revision, and neurologic injury), blood loss (EBL), operative time, length of stay (LOS), and patient reported questionnaires (ODI, SF-36, SRS). The impact of obesity was studied using multivariate Poisson, linear, or logistic regression modeling. Models accounted for confounders, as determined by univariate analysis and expert opinion. Results In total, 395 patients were identified (284 non-obese, 112 obese), with 2-year follow up on 225 patients. Regression models showed that obesity increased the risk of overall complications (IRR 1.28, P  = 0.01), major complications (IRR 1.57, P  = 0.005), and wound infection (OR 4.74, P  = 0.006). Absolute weight, but not BMI, increased the incidence of implant-related complications (weight – IRR 1.12 per 10 kg increase in weight P  = 0.05, BMI P  = 0.69) Obesity did not increase the number of minor complications ( P  = 0.33), radiographic complications ( P  = 0.75), neurologic complications ( P  = 0.48) or need for revision surgery ( P  = 0.74). Obesity was not significantly associated with OR time ( P  = 0.15), LOS ( P  = 0.9) or EBL ( P  = 0.38). Both groups experienced significant improvement over time, as measured on the ODI ( P  = 0.0001), SF-36 ( P  = 0.0001), and SRS ( P  = 0.0001). However, the overall improvement was less for obese patients (SRS P  = 0.02, ODI P  = 0.003, SF-36 P  = 0.001). They also had a lower rate of improvement over time (SRS P  = 0.008, ODI P  = 0.0001 SF-36 P  = 0.0001). Conclusions This study reveals that obese patients have an increased risk of complications following ASD correction. Despite increased complications, obese patients do benefit from ASD surgery, however their improvement in HRQOL is less than that of non-obese patients.