Operative Time Predicts Postoperative Outcomes in Bilateral DIEP Flap Reconstruction: Multivariate 1000 Flap Analysis

Background: Skin-to-skin operative time (OT) as a risk factor for adverse postoperative outcomes in microvascular breast reconstruction has not been thoroughly investigated. This study evaluates OT's impact on length of stay (LOS), overall morbidity, individual complications, and unplanned reoperation (UR) in deep inferior epigastric artery perforator (DIEP) flaps, with a primary objective of identifying a clinically relevant time of decreased odds. Methods: Patients who underwent bilateral DIEP flaps from 2010 to 2021 by two senior surgeons (N.T.H. and S.S.T.) with standardized surgical and postoperative protocols were retrospectively reviewed. One thousand flaps (500 patients) were analyzed with extensive multivariate regression equations to adjust for potential confounders, including intraoperative complexity. The odds of postoperative complication, extended LOS (eLOS, defined as ≥5 days) were compared across OT per hour and OT intervals. Results: After risk-adjustment, each hour of OT increased morbidity by 19%, UR by 8.7%, and LOS by 6.5 hours (all P < 0.001). For eLOS, procedures ≤5 hours had 9.5 times lower odds than ≥5 hours (P = 0.050), 5-7 hours had comparable odds (P = 0.540), and 7-9 hours had 5.5 times lower odds than procedures ≥ 9 hours (P < 0.001). Last, a multivariate linear regression showed that LOS can be calculated from OT: LOS (days) =1.527 + 0.272 × OT (hours) (R²= 0.308; P < 0.001). Conclusions: OT (per hour) independently predicts morbidity, UR and LOS in DIEP flaps. Furthermore, 5 and 9 hours are critical cutoffs for eLOS. These findings emphasize the benefits of decreasing OT through efficiency models, such as process analysis, team-based intraoperative protocols, and co-surgery model.