Risk Factors Associated with Free Flap Failure – an Analysis of 2103 Patients

Risk Factors Associated with Free Flap Failure – An Analysis of 2103 Patients

Background: The viability of microvascular free flaps depends upon various patient-based factors. The objective of this study was to identify such factors of patients at increased risk for flap failure.

Methods: The American College of Surgeons National Surgical Quality Improvement Program database (ACS-NSQIP) was queried for all patients who underwent microvascular free tissue transfer from 2005 through 2012. Patients were identified based upon the following CPT codes: 15756 (free muscle or myocutaneous flap with microvascular anastomosis), 15757 (free skin flap with microvascular anastomosis), 15758 (free fascial flap with microvascular anastomosis), and 19364 (breast reconstruction with free flap). Univariate analysis was performed to identify the association between free flap failure and the following factors: age, gender, race, body mass index (BMI), diabetes, smoking, alcohol, hypertension, intraoperative transfusion, functional health status, American Society of Anesthesiologists classification, operative time, and flap location. Factors yielding a significance of p <0.20 were included in multivariate logistic regression models in order to identify independent risk factor significance for flap failure. Furthermore, cases were stratified based upon recipient site (Breast, Head and Neck, Trunk, or Extremity), and analysis was repeated in order to identify risk factors specific to each location.

Results: 1921 of 2103 patients who underwent microvascular free flap reconstruction met inclusion criteria. Multivariate logistic regression identified BMI (AOR = 1.07, p=0.004) and male gender (AOR = 2.16, p=0.033) as independent risk factors for flap failure. Among the "Breast Flaps" subgroup, BMI (AOR=1.075, p=0.012) and smoking (AOR=3.35, p=0.02) were independent variables associated with flap failure. In "Head and Neck Flaps," operative time (AOR = 1.003, p=0.018) was an independent risk factor for flap failure. No independent risk factors were identified for the "Extremity Flaps" or "Trunk Flaps" subtypes.

Conclusion: BMI was identified as an independent risk factor for flap failure among all microvascular free flaps and within the "Breast Flaps" subcategory. Smoking additionally was identified as an independent risk factor within "Breast Flaps." Finally, increased operative time was a risk factor for flap failure among "Head and Neck Flaps."

Table 1.  Frequency of Microvascular Free Flaps Among Each Flap Category

Table 2. Multivariate Analysis Indicated Adjusted Odds Ratios for Flap Failure