D18. Optimizing Length of Stay after Abdominally Based Autologous Free-flap Reconstruction: An Analysis of 4,582 Flaps

PURPOSE: Length of stay after autologous breast reconstruction (ABR) remains controversial. Prior analyses indicate inpatient costs increase rapidly after POD 2, exceeding a willingness-to-pay threshold of $100,000/quality adjusted life-year. We evaluated the incidence and risk factors for flap complications after POD 2. METHODS: Patients undergoing ABR were included (2005-2019). Risk-adjusted logistic regression was then performed to evaluate the factors associated with flap loss after POD 2. RESULTS: A total of 4,582 free flaps were identified. The patient mean age was 51 (SD 9.8) years, BMI 29.2 (SD 5.9), 244 (8.4%) were current smokers, 222 (7.8%) were diabetics, and 745 (26.2%) had hypertension. Overall, 141 (5.0%) vascular complications were identified intraoperatively and revised. Ten of the flaps with intraoperative complications went on to have some degree of flap loss (7.1%) compared to 53 (2.0%) in the overall cohort (P<0.001). Subsequently, 69 (2.4%) microvascular complications occurred in the post-operative period, of which 50 (72.5%) of these occurred by or on POD2. Fifteen (29%%) were venous and 15 (29%%) were arterial complications, while the rest were classified as "other" (i.e. mechanical compression). There were 32 total flap losses; 59.4% occurred by POD 2. Predictors of flap loss after POD2 were smoking (OR 2.65 [95% CI: 1.05-6.68], P=0.039) and higher BMI (OR 1.08 [95% CI: 1.04-1.14], P=0.001). CONCLUSION: With microvascular compromise occurring most often by POD2, patients undergoing AABR without predictive risk factors may be discharged early (ie. <POD3) with clinical monitoring at home to reduce unnecessary cost to the healthcare system.