Validation of the Webb and Rivera Score in Predicting Complexity of Mohs Surgery Procedures: A Retrospective Study

Abstract

Background: Mohs micrographic surgeries (MMSs) vary in complexity and corresponding procedural duration. Preoperative triage of MMS cases enables physicians to estimate procedure duration and create an efficient schedule. The Webb and Rivera (WAR) score is a quantitative formula developed to predict complexity in Mohs cases based on tumor diameter, history of recurrence, location, and aggressiveness. Patients are given a score between 0 and 5 based on this information, with increasing surgical complexity for higher scores. Purpose: We aim to assess the association between WAR score, the number of stages, and repair type used in MMS to determine its value for clinical practice. Methods: Data for WAR score calculation were collected and analyzed for patients with squamous cell carcinoma and/or basal cell carcinoma treated with MMS between 2019 and 2023. Analyses were performed to determine if there was significant heterogeneity across WAR score groups. The Mantel–Haenszel Chi-square tests were performed for ordered categorical variables (Mohs stage), and Chi-square tests were performed for nonordered categorical variables. The results were verified using Fisher’s exact test when more than 25% of cells had an expected count of <5. Analyses were performed using SAS v9.4 (SAS Institute, Cary, NC). Results: Of the 712 patients who underwent MMS, 153 (21%) had a WAR score of 0, 270 (38%) had a WAR score of 1, 189 (26%) had a WAR score of 2, 75 (10%) had a WAR score of 3, 23 (3.2%) had a WAR score of 4, and 2 (0.2%) had a WAR score of 5. The average number of surgical stages increased as the WAR score increased, and the percentage of repairs using a flap or graft similarly increased for higher scores. While 86.2% of patients with a WAR score of 0 were cleared with one stage, this decreased to 75.5% with a score of 1, 74.6% with a score of 2, 72% with a score of 3, and 52.1% with a score of 4. Only two cases had a score of 5, both of which required two stages. In addition, only 13.7% of tumors with a WAR score of 0 required closure with a flap or graft, in comparison with 24.2% with a score of 1, 33.9% with a score of 2, 47.9% with a score of 3, and 47.7% with a score of 4. Conclusion: This study demonstrates that the WAR score is an effective predictive tool for identifying cases that may require multiple stages and more complex reconstructive techniques. Given that more complex cases will require increased operative time, a scheduling template that accounts for the level of complexity can lead to a more effective schedule. The WAR score may provide a practical tool for Mohs surgeons and their staff to triage incoming cases and design a schedule that allows for a consistent workflow.