Impact of obesity on complications and surgical outcomes after adult degenerative scoliosis spine surgery

Objective: To compare perioperative outcomes of obese versus non-obese adult patients who underwent degenerative scoliosis spine surgery. Methods: 235 patients who underwent thoracolumbar adult spinal deformity (ASD) surgery (≥4 levels) were identified and categorized into two cohorts based on their body mass indices (BMI): obese (BMI ≥30 kg/m²; n = 81) and non-obese (BMI <30 kg/m²; n = 154). Preoperative (demographics, co-morbidities, American Society of Anesthesiologists (ASA) score and modified frailty indices (mFI-5 and mFI-11)), intraoperative (estimated blood loss (EBL) and anesthesia duration), and postoperative (complication rates, Oswestry Disability Index (ODI) scores, discharge destination, readmission rates, and survival) characteristics were analyzed by student's t, chi-squared, and Mann-Whitney U tests. Results: Obese patients were more likely to be Black/African-American (p < 0.05, OR:4.11, 95% CI:1.20–14.10), diabetic (p < 0.05, OR:10.18, 95% CI:4.38–23.68) and had higher ASA (p <.01) and psoas muscle indices (p < 0.0001). Furthermore, they had greater pre- and post-operative ODI scores (p < 0.05) with elevated mFI-5 (p < 0.0001) and mFI-11 (p < 0.01). Intraoperatively, obese patients were under anesthesia for longer time periods (p < 0.05) with higher EBL (p < 0.05). Postoperatively, while they were more likely to have complications (OR:1.77, 95% CI:1.01 – 3.08), had increased postop days to initiate walking (p <.05) and were less likely to be discharged home (OR:0.55, 95% CI:0.31–0.99), no differences were found in change in ODI scores or readmission rates between the two cohorts. Conclusions: Obesity increases pre-operative risk factors including ASA, frailty and co-morbidities leading to longer operations, increased EBL, higher complications and decreased discharge to home. Pre-operative assessment and systematic measures should be taken to improve peri-operative outcomes.