Who Remains Intubated After Adult Spinal Deformity Surgery? A 5-Factor Scoring System With Dual Institution External Validation

BACKGROUND AND OBJECTIVES: Prolonged intubation is an unwanted occurrence after adult spinal deformity (ASD) surgery, yet its risk factors are poorly understood. For patients undergoing ASD surgery, we sought to: (1) report the rate of intubation until postoperative day 1 (POD 1), (2) create a scoring system to predict it, and (3) externally validate the scoring system. METHODS: A retrospective cohort study (2009-2021) was performed for patients undergoing ASD surgery. Primary outcome was prolonged intubation (POD 1 or beyond). Univariate logistic regression were performed. External validation was performed using an independent cohort. RESULTS: Among 233 patients, 36 (15%) remained intubated until at least POD 1. These patients were older (70 vs 62 years, P = .001), had longer surgeries (543 vs 398 minutes, P < .001), late procedure end times (18:34 vs 15:59, P < .001), change of anesthetists (56% vs 31%, P = .04), greater blood loss (2809 vs 1207 mL, P < .001), and required intraoperative blood transfusion (89% vs 54%, P < .001). For every extra 30 minutes the case continued, odds of prolonged intubation increased by 22% (odds ratio = 1.2, 95% CI: 1.1-1.3, P < .001). The final scoring system included: age 60 years and older, intraoperative blood transfusion, operative time >7 hours, change of anesthetists, and procedure close time after 17:00. Receiver operating characteristic analysis revealed a cutoff of >4 points as a predictor of prolonged intubation (area under the curve = 0.8, 95% CI: 0.8-0.9, P < .001, sensitivity = 89%, specificity = 70%). On external validation, the score demonstrated moderate discriminative ability (area under the curve = 0.7). At the threshold of 4, sensitivity was 91%, and specificity was 26%. CONCLUSION: Approximately 15% ASD surgery patients remained intubated through POD 1. An 8-point risk score incorporating age 60 years and older, operative time ≥7 hours, intraoperative transfusion, change of anesthetists, and procedure end time after 17:00 demonstrated strong discrimination in the derivation cohort and moderate, high-sensitivity performance on external validation. Use of this score in collaboration with anesthesia teams may enable early risk stratification and targeted perioperative planning.