The Surgical Apgar Score can help predict postoperative complications in femoral neck fracture patients: a 6-year retrospective cohort study

Abstract

Introduction The postoperative mortality rate following a femoral neck fracture remains high. The Surgical Apgar Score (SAS), based on intraoperative blood loss, the lowest mean arterial pressure, and the lowest heart rate, was created to predict 30-day postoperative major complications. Here, we evaluated the relationship between the SAS and postoperative complications in patients who underwent femoral neck surgeries. Methods We retrospectively collected data from patients with femoral neck surgeries performed in 2012-2017 at Kumamoto Central Hospital. The variables required for the SAS and the factors presumably associated with postoperative complications including the patients' characteristics were collected from the medical charts. Intergroup differences were assessed with the χ 2 test with Yates' correlation for continuity in category variables. The Mann-Whitney U test was used to test for differences in continuous variables. We assessed the power of the SAS value to distinguish patients who died ≤ 90 days post-surgery from those who did not, by calculating the area under the receiver operating characteristic curve (AUC). Results We retrospectively examined the cases of 506 patients (94 men, 412 women) aged 87 ± 6 (range 70-102) years old. The 90-day mortality rate was 3.4% (n = 17 non-survivors). There were significant differences between the non-survivors and survivors in body mass index (BMI), the presence of moderate to severe valvular heart disease, albumin concentration, the American Society of Anesthesiologists (ASA) classification, and the SAS. The 90-day mortality rate in the SAS ≤ 6 group (n = 97) was 10.3%, which was significantly higher than that in the SAS ≥ 7 group (n = 409), 1.7%. The AUC value to predict the 90-day mortality was 0.70 for ASA ≥ 3 only, 0.71 for SAS ≤ 6 only, 0.81 for SAS ≤ 6 combined with ASA ≥ 3, and 0.85 for SAS ≤ 6 combined with albumin concentration < 3.5 g/dl, BMI ≤ 20, and the presence of moderate to severe valvular heart disease. Conclusions Our results suggest that the SAS is useful to evaluate postoperative complications in patients who have undergone a femoral neck surgery. The ability to predict postoperative complications will be improved when the SAS is used in combination with the patient's preoperative physical status.