An assessment of the Surgical Apgar Score in spine surgery

Background contextThe Surgical Apgar Score (SAS), a simple metric based on intraoperative heart rate, blood pressure, and blood loss, was developed in general and vascular surgery to predict 30-day major postoperative complications and mortality. No validation of SAS has been performed in spine surgery.PurposeTo perform a prospective assessment of SAS in spine surgery.Study designProspective study.Patient sampleTwo hundred sixty-eight consecutive patients undergoing major and intermediate spinal surgeries in an 18-month period.Outcome measuresOccurrence of major complications or death within 30 days of surgery.MethodsIntraoperative parameters were registered, and SAS was calculated immediately after surgery. Outcome data were collected during a 30-day follow-up. The relationship between SAS and the outcomes was analyzed calculating relative risks (RRs) and likelihood ratios (LRs) for different scoring groups. A univariate logistic regression analysis was also performed. The discriminatory accuracy of SAS was evaluated calculating a C-statistic.ResultsEighteen patients had ≥1 complications (6.72%). Patients with SAS 9-10 exhibited a 1.64% complication rate (RR=1; LR=0.23), which monotonically augmented as the score decreased: (SAS 7–8=2.75%; RR=1.68; LR=0.39), (SAS 5–6=13.33%; RR=8.13; LR=2.14), (SAS≤4=17.39%; RR=10.61; LR=2.92). The regression analysis odds ratio was 0.66 (95% confidence interval, 0.54–0.82), p<.01. The C-statistic was 0.77 (95% confidence interval, 0.66–0.88).ConclusionsSurgical Apgar Score allows risk stratification and has a good discriminatory power in patients undergoing spine surgery.