Independent Predictors of Early Flap Failure and Readmission Following Oral Cavity Microvascular Free Flap Reconstruction: A 7-Year Risk-Adjusted Cohort Study.

BACKGROUND

Microvascular free flap reconstruction is the standard for complex oral oncologic defects, with success rates exceeding 95% in high-volume centres. However, early flap failure and unplanned readmission remain clinically significant, and the relative impact of flap selection versus patient-related factors remains unclear.

METHODS

We conducted a retrospective cohort study of 690 consecutive oral cavity free flap reconstructions performed between 2017 and 2024. Each flap was analysed as an independent observation. Baseline demographics, prior radiotherapy, and comorbidity burden were recorded. Multivariable logistic regression identified predictors of 30-day readmission, and Cox proportional hazards modelling evaluated independent predictors of 30-day flap failure.

RESULTS

Overall flap survival was 95.1% (656/690), with 34 total flap losses (4.9%), 33 occurring within the first 4 postoperative days. Re-exploration for vascular compromise was required in 10.1% of cases, with a salvage rate of 71.4%. On multivariable Cox regression, prior radiotherapy (HR 6.63, 95% CI 3.28-13.41, p<0.001) and Charlson-Deyo score ≥3 (HR 2.11, 95% CI 1.07-4.15, p=0.031) independently predicted flap failure. Thirty-day readmission occurred in 12.4% and was independently associated with prior radiotherapy (OR 4.64), comorbidity burden (OR 3.29), and salvage resection (OR 4.42) (all p<0.001). Flap composition was independently associated with early flap failure, with soft tissue flaps demonstrating lower odds of failure compared to bony flaps (adjusted OR 0.23, 95% CI 0.10-0.52, p < 0.001).

CONCLUSION

Patient-related factors, particularly prior radiotherapy and comorbidity, remain the primary determinants of flap failure and readmission, although flap composition also independently influences outcomes, with higher risk in bony reconstructions.