Published online Dec 18, 2016. doi: 10.5312/wjo.v7.i12.832
Peer-review started: June 27, 2016
First decision: August 11, 2016
Revised: September 19, 2016
Accepted: October 25, 2016
Article in press: October 27, 2016
Published online: December 18, 2016
To assess whether the surgical apgar score (SAS) is a prognostic tool capable of identifying patients at risk of major complications following lower extremity amputations surgery.
This was a single-center, retrospective observational cohort study conducted between January 2013 and April 2015. All patients who had either a primary transtibial amputation (TTA) or transfemoral amputation (TFA) conducted at our institution during the study period were assessed for inclusion. All TTA patients underwent a standardized one-stage operative procedure (ad modum Persson amputation) performed approximately 10 cm below the knee joint. All TTA procedures were performed with sagittal flaps. TFA procedures were performed in one stage with amputation approximately 10 cm above the knee joint, performed with anterior/posterior flaps. Trained residents or senior consultants performed the surgical procedures. The SAS is based on intraoperative heart rate, blood pressure and blood loss. Intraoperative parameters of interest were collected by revising electronic health records. The first author of this study calculated the SAS. Data regarding major complications were not revealed to the author until after the calculation of SAS. The SAS results were arranged into four groups (SAS 0-4, SAS 5-6, SAS 7-8 and SAS 9-10). The cohort was then divided into two groups representing low-risk (SAS ≥ 7) and high-risk patients (SAS < 7) using a previously established threshold. The outcome of interest was the occurrence of major complications and death within 30-d of surgery.
A logistic regression model with SAS 9-10 as a reference showed a significant linear association between lower SAS and more postoperative complications [all patients: OR = 2.00 (1.33-3.03), P = 0.001]. This effect was pronounced for TFA [OR = 2.61 (1.52-4.47), P < 0.001]. A significant increase was observed for the high-risk group compared to the low-risk group for all patients [OR = 2.80 (1.40-5.61), P = 0.004] and for the TFA sub-group [OR = 3.82 (1.5-9.42), P = 0.004]. The AUC from the models were estimated as follows: All patients = [0.648 (0.562-0.733), P = 0.001], for TFA patients = [0.710 (0.606-0.813), P < 0.001] and for TTA patients = [0.472 (0.383-0.672), P = 0.528]. This indicates moderate discriminatory power of the SAS in predicting postoperative complications among TFA patients.
SAS provides information regarding the potential development of complications following TFA. The SAS is especially useful when patients are divided into high- and low-risk groups.
Core tip: This study presents new knowledge regarding the use of Surgical Apgar Score (SAS) in dysvascular lower extremity amputations (LEA) surgery. There is a significant increase in complications with a low SAS after LEA surgery. This is even more pronounced when the transfemoral amputation (TFA) sub-group is analyzed separately. Thus, for a TFA patient with a SAS < 7, the odds of a major complication or death is four times greater than for a patient with a SAS ≥ 7. ROC analysis confirms the discriminatory power of the SAS approach among the TFA patients. However, the SAS model proved to be of no prognostic value in the transtibial amputation group.