Optimizing the Risk Stratification Tools for Patients Undergoing Cranioplasty

BACKGROUND: Large size cranioplasty (>25cm2) after decompressive hemicraniectomy is associated with failure rates as high as 30-50%. Current risk stratification approaches for patients undergoing cranioplasty patients did not however take into consideration the cranioplasty sizes.1 Patients requiring large size cranioplasty usually have a baseline higher modified frailty index -5 (mfi-5) and risk analysis index (RAI) scores than other patient populations. These scores are direct indicators of frailty and have been shown to have a predictive utility for postoperative outcomes.1 The aim of this study is to determine predictive utility of these scores for surgical outcomes in patients undergoing large size cranioplasty. METHODS: A retrospective review of adult patients undergoing large defect cranioplasty at The Ohio State University (2013–2022) was conducted. Individual RAI-A and mFI-5 scores were calculated used to stratify patients into high (RAI >30 and mfi-5 ≥3) and low (RAI ≤30 and mfi-5 ≤2) risk group. Logistic regression and ROC analysis was used to determine the relationship with postoperative outcome. RESULTS: The analysis included 302 patients (mean age 50.5 years). Reoperation occurred in 28.8%, Clavien-Dindo III-IV complications in 28.4%, 30-day morbidity in 32.7%, and cranioplasty failure in 11.6%. Patients with RAI >30 or mFI-5 ≥3 had higher reoperation risk (p=0.012, p=0.008, respectively), with both scores showing robust predictive accuracy (AUC: 0.85). Reoperation risk was elevated for patients with prior surgeries (p<0.0001) and frontoparietal cranioplasties (p=0.02). RAI >30 increased 30-day morbidity risk (p=0.033), particularly in patients with frozen autogenous bone grafts (p=0.02), with RAI outperforming mFI-5 (AUC: 0.75). Conversely, mFI-5 demonstrated superior prediction of graft failure (AUC: 0.86), with mFI-5 ≥3 significantly associated with hardware/graft failure (p=0.00012). CONCLUSIONS: We have shown that RAI and mfi-5 scores can help stratify patients risks of postoperative complications. Further, these scores have different discriminatory ability on the specific type of complication. The scores may be helpful for preoperative identification and optimization of patients that are likely to have a complicated postoperative course.