A Risk Calculator for the Prediction of C5 Nerve Root Palsy After Instrumented Cervical Fusion

BACKGROUND: C5 palsy is a common postoperative complication after cervical fusion and is associated with increased health care costs and diminished quality of life. Accurate prediction of C5 palsy may allow for appropriate preoperative counseling and risk stratification. We pri-marily aim to develop an algorithm for the prediction of C5 palsy after instrumented cervical fusion and identify novel features for risk prediction. Additionally, we aim to build a risk calculator to provide the risk of C5 palsy.METHODS: We identified adult patients who underwent instrumented cervical fusion at a tertiary care medical center between 2013 and 2020. The primary outcome was postoperative C5 palsy. We developed ensemble machine learning, standard machine learning, and logistic regres-sion models predicting the risk of C5 palsy -assessing discrimination and calibration. Additionally, a web-based risk calculator was built with the best-performing model. RESULTS: A total of 1024 patients were included, with 52 cases of C5 palsy. The ensemble model was well -calibrated and demonstrated excellent discrimination with an area under the receiver-operating characteristic curve of 0.773. The following features were the most important for ensemble model performance: diabetes mel-litus, bipolar disorder, C5 or C4 level, surgical approach, preoperative non-motor neurologic symptoms, degenera-tive disease, number of fused levels, and age.CONCLUSIONS: We report a risk calculator that gener-ates patient-specific C5 palsy risk after instrumented cervical fusion. Individualized risk prediction for patients may facilitate improved preoperative patient counseling and risk stratification as well as potential intraoperative mitigating measures. This tool may also aid in addressing potentially modifiable risk factors such as diabetes and obesity.