Risk factors associated with postoperative complications of free anterolateral thigh flap placement in patients with head and neck cancer: Analysis of propensity score-matched cohorts.

BACKGROUND: From the perspective of a surgeon, knowledge of the operative risk factors that may affect postoperative outcomes is important in free anterolateral thigh (ALT) flap reconstruction for head and neck defects after tumor ablation. Therefore, this study was designed to examine the surgical intervention factors related to postoperative complications in a propensity score matched patient population. PATIENTS AND METHODS: A total of 1,284 head and neck cancer patients who received free ALT flap repair over a 9-year period from March 1, 2008, to February 28, 2017, at a single medical center were selected and divided into two groups (without complications, n = 845 and with complications, n = 439) according to the presence or absence of complications at the recipient site. Complications were defined as the detection of hematoma, surgical site infection, partial flap loss, oral fistula formation, flap partial necrosis, and flap loss. Well-balanced propensity score-matched cohorts with 292 patients each were created using the 1:1 Greedy algorithm, with adjustment for significant baseline patient characteristics. RESULTS: The patients with postoperative complications had a higher proportion of individuals with betel nut chewing (91.8% vs. 86.6%, p = .008), diabetes mellitus (23.0% vs. 17.8%, p = .029), and preoperative chemotherapy (31.7% vs. 25.3%, p = .019), and higher serum creatinine levels (median [Q1-Q3]: 0.92 [0.80-1.07] vs. 0.89 [0.77-1.06], p = .008) and lower serum albumin levels (4.2 [3.9-4.5] vs. 4.3 [4.1-4.5], p < .001) than those without postoperative complications. Individual operator (p < .001), the length of flap (20 [15-23] cm vs. 20 [15-25] cm, p < .001), operative time (6.9 hr [5.7-8.3 hr] vs. 7.3 hr [5.9-8.7 hr], p = .001), operation start time (p = .003), and units of transfused packed red blood cells (0.0 [0.0-0.0] units vs. 0.0 [0.0-2.0] units, p < .001) were the factors significantly associated with the occurrence of postoperative complications. However, in the matched patient cohorts, individual operator (p = .003), flap length (18 [15-22] cm vs. 20 [15-25] cm, p < .001) and length-to-width ratio (2.6 [2.0-3.3] vs. 3.0 [2.5-3.6], p < .001), and operative time (6.9 hr [5.7-8.3 hr] vs. 7.2 hr [5.9-8.7 hr], p = .019) were associated with the occurrence of postoperative complications, but the operation start time (p = .285) and units of transfused packed red blood cells (p = .917) were not. CONCLUSIONS: This study demonstrated in matched patient cohorts that individual operator, flap size, and operative time were associated with postoperative complications of free ALT flap reconstruction in patients with head and neck cancer. To reduce the postoperative complication rate, this study implies the importance of length and length-to-width ratio in harvesting the flap, and meanwhile the surgeon experience in free-flap reconstruction.