151751-Najiba-Chargi

127 Surgery: skeletal muscle mass, systemic inflammation and flap reconstruction LOS (16.6 days, SD 10.5) compared to patients without low SMM (15.7 days, SD 17.0 days) (mean difference 0.9 days, 95%CI -1.8-3.5, p=0.5). This difference was not statistically signifi - cant. Patients with elevated NLR had a significant risk for longer LOS (17.7 days; SD 17.0 days) compared to patients with low NLR (14.5 days; SD 9.2 days) (mean difference 3.2 days, 95%CI 0.5-5.9, p=0.02). Also, patients with elevated NLR and low SMM had a significant longer LOS (17.3 days, SD 10.4) compared to patients without combined elevated NLR and low SMM (13.5 days, SD 7.7) (mean difference 3.9 days, 95% CI 1.4-6.3 days, p=0.002). SURVIVAL ANALYSIS Median follow-up time was 39.5 months (IQR 18.0-76.5). At the end of the study, 289 (46.9%) patients died, and 190 (34.2%) oncological patients developed a recurrence. Figure 2. shows the Kaplan Meier survival curves for DFS and OS for all patients. As shown, elevated NLR (Log rank χ 2 = 4.4, p=0.04) was prognostic for decreased DFS and low SMM (Log rank χ 2 = 4.2, p=0.04) and elevated NLR (Log rank χ 2 = 6.0, p=0.02) were prognostics for de - creased OS. Due to the heterogeneity of reasons for reconstructive surgery and also heterogeneity in tumor histology, we choose to perform survival analysis for the subgroup of patients with HNSCC (n=507). SMM and NLR status was only available in a subgroup of HNSCC patients (n=352), therefore we choose to evaluate the prognostic impact of these variables and other variables in this subgroup. Because TNM stage is a known prognostic factor, we decided to investigate the prognostic impact of low SMM and elevated NLR in patients with early (TNM stage I-II) and advanced stage (TNM stage III-IV) HNSCC. Table 4 shows the univariate and multivariate cox regression analysis of prognostic variables for DFS and OS. For DFS, multivariate analysis determined age to be prognostic in early stage HNSCC (HR 1.04, 1.01-1.1, p<0.05) and in ad - vanced stage HNSCC (HR 0.98; 0.96-0.99, p=0.02). For OS, in patients with early stage HNSCC, multivariate analysis showed low SMM (HR 2.3, 95%CI 1.2-4.4, p=0.01) and combined elevated NLR with low SMM (HR 2.6, 95%CI 1.1-6.0, p=0.03) to be significant prognostics for decreased OS, independent of comorbidity. Age and gender were not included in multivariate analysis due tomulticollinearity between SMM and age (r 2 =-0.4; p<0.001) and SMM and gender (r 2 =0.62; p<0.001). For OS, in patients with advanced stage HNSCC, in multivariate analysis only BMI (HR 0.9; 95%CI 0.9-0.98, p<0.001) and hemoglobin (HR 0.99, 95%CI 0.98-0.99, p=0.03) were prognostic for decreased OS. 7