Validation of ERICVA Risk Score as a Predictor of One Year Amputation-Free Survival of Patients with Critical Limb Ischemia

BACKGROUND: The ERICVA score was derived to predict amputation-free survival in patients with critical limb ischemia (CLI). It may be a useful tool to stratify patients in trials of novel interventions to treat CLI but, as yet, it has not been externally validated. METHODS: A prospective database of CLI patients was developed during prescreening of patients for a phase 1 stem cell therapy clinical trial. The primary outcome was amputation free survival (AFS) at 1 year. Both the full ERICVA scale (11 parameters) and simplified ERICVA scale (5 parameters) were validated. Data analysis was performed by calculation of the area under the receiver operating characteristic (ROC) curve examining the predictive value of the scores. The Chi-square test was used to examine the association between risk group and one-year AFS and the cumulative survival of the three risk groups was compared using Kaplan Meier survival curves. RESULTS: A series of 179 CLI patients were included in the analysis. The Chi-square test of independence showed a significant association between the risk group (high, medium and low) and one-year AFS outcome (P = 0.0007). Kaplan-Meier survival curve showed significant difference in one-year AFS between the three risk groups (log-rank P < 0.001). The area under the curve (AUC) was found to be 0.63 and 0.61 for the full and simplified score, respectively. The sensitivity of the full score was 0.44 with specificity of 0.84. The simplified score had a sensitivity of 0.28 and specificity of 0.92. CONCLUSION: The ERICVA risk score system was found to have a fair validity but cannot be considered reliable as a single predictor of one year AFS of CLI patients. The simplified score had an AUC almost identical to the full score and can accordingly replace the full score.