Does the ACS NSQIP Surgical Risk Calculator Accurately Predict Complications Rates After Anterior Lumbar Interbody Fusion Procedures?

Ankur S. Narain, MD; Alexander Z. Kitto, MD; Benjamin Braun, MD; Matthew J. Poorman, MD; Patrick Curtin, MD; Justin Slavin, MD; Giles Whalen, MD; Christian P. DiPaola, MD; Patrick J. Connolly, MD; Michael P. Stauff, MD


Spine. 2021;46(12):E655-E662. 

In This Article

Abstract and Introduction


Study Design: Clinical case series.

Objective: The aim of this study was to determine the effectiveness of the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) surgical risk calculator in the prediction of complications after anterior lumbar interbody fusion (ALIF).

Summary of Background Data: Identifying at-risk patients may aid in the prevention of complications after spine procedures. The ACS NSQIP surgical risk calculator was developed to predict 30-day postoperative complications for a variety of operative procedures.

Methods: Medical records of patients undergoing ALIF at our institution from 2009 to 2019 were retrospectively reviewed. Demographic and comorbidity variables were entered into the ACS NSQIP surgical risk calculator to generate percentage predictions for complication incidence within 30 days postoperatively. The observed incidences of these complications were also abstracted from the medical record. The predictive ability of the ACS NSQIP surgical risk calculator was assessed in comparison to the observed incidence of complications using area under the curve (AUC) analyses.

Results: Two hundred fifty-three (253) patients were analyzed. The ACS NSQIP surgical risk calculator was a fair predictor of discharge to non-home facility (AUC 0.71) and surgical site infection (AUC 0.70). The ACS NSQIP surgical risk calculator was a good predictor of acute kidney injury/progressive renal insufficiency (AUC 0.81). The ACS NSQIP surgical risk calculator was not an adequate predictive tool for any other category, including: pneumonia, urinary tract infections, venous thromboembolism, readmission, reoperations, and aggregate complications (AUC < 0.70).

Conclusion: The ACS NSQIP surgical risk calculator is an adequate predictive tool for a subset of complications after ALIF including acute kidney injury/progressive renal insufficiency, surgical site infections, and discharge to non-home facilities. However, it is a poor predictor for all other complication groups. The reliability of the ACS NSQIP surgical risk calculator is limited, and further identification of models for risk stratification is necessary for patients undergoing ALIF.

Level of Evidence: 3


As health care analytics increase in their complexity and ability to capture adverse outcomes, there has been an increasing focus on value. Health care value is commonly defined as quality of care delivered per unit cost.[1] The American College of Surgeons (ACS) has been at the forefront of this movement with the advent of the National Surgical Quality Improvement Program (NSQIP) database. This is a large administrative database that measures aspects of a patient's care during a surgical encounter, ranging from preoperative demographics to 30-day postoperative complications. This database has further been used to devise the ACS NSQIP surgical risk calculator, which is an online tool that predicts the likelihood of adverse events in surgical patients based on procedure and individual comorbidity profiles.[2] Although the accuracy of the ACS NSQIP surgical risk calculator has been investigated for many general surgical procedures, its use in orthopedics and spinal surgery is not yet fully elucidated.

Anterior lumbar interbody fusion (ALIF) is a commonly performed spinal procedure, in which the lower lumbar spine is accessed via the abdomen (either via a trans-peritoneal or retroperitoneal approach), and an interbody cage or allograft material is placed into the prepared disk space with or without instrumentation. Most commonly this is performed at levels L5-S1 and L4–5, with occasional extension to L3–4. In some cases, these procedures may also have a concomitant posterior decompression and/or fusion.[3] ALIF procedures have multiple indications, most commonly in the treatment of lumbar degenerative conditions, including spondylolisthesis and spinal deformity correction.[4]

Although the ACS NSQIP surgical risk calculator has been investigated in patients undergoing posterior lumbar or cervical fusions,[5] no study has been performed evaluating patients undergoing ALIF procedures. The primary purpose of this study is to use our institutional experience with ALIF procedures to determine the accuracy of adverse event prediction from the ACS NSQIP surgical risk calculator. Secondarily, this study will analyze the complication profile for patients undergoing ALIF procedures at a single institution. We hypothesize that the ACS NSQIP surgical risk calculator will not have a significant association with, and thus will not be an accurate predictor of, the incidence of total complications after ALIF procedures.