Evaluating the Merit and Applications of the Caprini Risk Score as a Complication Predictor

Background: Venous thromboembolism (VTE) is considered a complication of free flap surgery. Prior studies investigating the use of Caprini Risk Score (CRS) to estimate risk of complications in free flap reconstruction are confounded by small sample sizes, varying surgical sites, and disparate classification of risk. This study evaluates the predictive merit of CRS for complications in free flap reconstructions. Methods: A retrospective review of patients (n=502) who underwent free flap reconstruction from January 2015 to April 2022 collected patient medical history, type and location of free tissue transfer, CRS, and prior and perioperative anticoagulation (AC). Reconstructive outcomes and complications were analyzed in low (CRS<8) and high (CRS≥8) cohorts using chi-squared tests. Complications were also analyzed by flap sites in sufficient cohort populations (n>10). Results: Of 502 patients, the high CRS cohort (n=71) were associated with upper (p<0.005) and lower (p<0.001) extremity reconstructions while the low CRS (n=431) cohort were associated with breast reconstructions (p<0.001). The high CRS cohort demonstrated an increased need for intraoperative blood transfusions (p<0.001). Other intra-operative or post-operative complications such as flap loss, intraoperative AC, return to OR, or VTE had no significant correlations. High CRS patients were more likely to be discharged on AC (p<0.001) and have a longer length of stay (LOS) (p<0.001). By flap site, there was a significant association between CRS and LOS >14 days in breast and head and neck flaps (p<0.05) and discharge on AC in head and neck flaps only (p<0.001). Conclusion: CRS may have utility in predicting the need for blood transfusion and AC requirements in free flap reconstruction but does not seem to predict incidence of flap complications. A larger, higher-powered study may be used to assess the validity of CRS in risk of VTE and anticoagulant prophylaxis.