The CARDE-B Scoring System Predicts 30-Day Mortality After Revision Total Joint Arthroplasty

BACKGROUND: There exists a substantial risk of having a perioperative complication after revision total joint arthroplasty (TJA). The complex shared decision-making between surgeon and patient would benefit from a high-fidelity tool to identify patients at risk for mortality after revision TJA. Therefore, we developed the CARDE-B score. CARDE-B is an acronym for congestive heart failure, albumin or malnutrition (<3.5 mg/dL), renal failure on dialysis, dependence for daily living, elderly (>65 years of age), and body mass index <25 kg/m2. We developed and validated the CARDE-B score to determine the risk of death within 30 days of a revision TJA. METHODS: A total of 13,118 revision TJAs (40% hip and 60% knee) from the National Surgical Quality Improvement Program (NSQIP) database were analyzed. A simple 1-point scoring system, CARDE-B, was created for predicting 30-day mortality after revision TJA, based on a logistic regression model. The CARDE-B scoring system assigns 1 point to each criterion in the acronym: congestive heart failure, albumin (<3.5 mg/dL), renal failure on dialysis, dependence for daily living, elderly (>65 years of age), and body mass index of <25 kg/m2. The CARDE-B scoring system was compared with 2 commonly utilized scores: American Society of Anesthesiologists (ASA) physical status classification and the 5-factor modified frailty index (mFI-5). The area under the curve (AUC) was used to assess the accuracy of each model. The Hosmer-Lemeshow test was used to assess goodness of fit. Finally, the Nationwide Inpatient Sample (NIS) was used for external validation of the CARDE-B score in 19,153 patients who underwent revision TJA in 2017. RESULTS: Eighty-eight patients (0.7%) did not survive 30 days after revision TJA. The AUC for the logistic regression model was 0.88 in both the derivation and internal validation samples using NSQIP. The predicted probability of 30-day mortality after revision TJA increased stepwise from <0.01% for a CARDE-B score of 0 points to 39% for a CARDE-B score of 5 points. The AUC for the CARDE-B score predicting 30-day mortality after revision TJA was 0.85. This was more accurate (p < 0.001) than the ASA physical status classification (AUC, 0.77) and the mFI-5 (AUC, 0.67). The AUC for the CARDE-B score in the NIS external validation set was 0.75. The Hosmer-Lemeshow p value for goodness of fit was 0.34, indicating goodness of fit in the external validation sample. CONCLUSIONS: The CARDE-B score is a simple system that predicts the risk of death within 30 days of a revision TJA, offering surgeons and patients a valuable and validated risk-stratification tool. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.