151751-Najiba-Chargi

144 CHAPTER 8 MATERIAL AND METHODS ETHICAL CONSIDERATIONS The local Medical Research Ethics Committee gave approval for this retrospective cohort study (reference number 17-208/C). PATIENTS AND STUDY DESIGN Patients who had surgery for OSCC at the University Medical Center Utrecht, the Netherlands, between September 2014 and January 2017 were identified from the departmental database. Inclusion criterion was the presence of a preoperative CT or MRI scan. All patients had been treated according to the national guidelines [27]. The surgical procedures had been performed by surgeons, dedicated to head and neck surgery. Potential risk factors for perioperative com - plications were collected from the electronic medical records: age, sex, body-mass index (BMI), comorbidity, alcohol intake, tumor, node, metastasis (TNM) stage (7 th edition) 27 , blood loss measured as decrease in hemoglobin level (mmol/L) following surgery, type of operation and operating time (in hours) (see Table 1 and 2). The comorbidity was determined using the American Society of Anesthesiologists (ASA) classi - fication system: ASA 1 for normal and healthy patient; ASA 2 for mild, systemic diseases; ASA 3 for severe systemic diseases; ASA 4 for severe systemic disease that is a constant threat to life; ASA 5 for patient not expected to survive without surgery. The overall comorbidity score was also determined with the Adult Comorbidity Evaluation system (ACE-27). The ACE-27 system identifies and grades 27 important ailments and gives an objective overall comorbidity score for the individual patient: 0 (none), 1 (mild), 2 (moderate) or 3 (severe). 28,29 The overall comor- bidity score is defined according to the highest ranked single ailment, except in the case where two or more Grade 2 ailments occur in different organ systems. In this situation, the overall comorbidity score is designated Grade 3. OUTCOME VARIABLES Perioperative data were obtained from the medical records: myocardial ischemia, acute myo- cardial infarction, congestive cardiac failure, thrombosis, pulmonary embolism, pneumonia, dysregulated diabetes, fever, postoperative hemorrhage, hematoma, wound dehiscence, wound infection, revision of the anastomosis, flap failure, jaw fracture, nerve damage, seroma, unexpected use of feeding tube, deliriumand the length of hospital stay. Perioperative compli - cations were defined according to Patel et al. 30 as any unanticipated adverse event requiring intervention or prolonging length of hospital stay. The perioperative complication rate was measured as presence and number of perioperative complications. SKELETAL MUSCLE MASS MEASUREMENT SMM was determined from a single CT-slice at the level of the third cervical vertebra (C3) ac - cording to the method described by Swartz et al. 26 When scrolling in caudo-cephalic direction,