Joeky Senders

72 Chapter 4 discharge from the hospital. In this retrospective cohort study, we assessed whether prolonged thromboprophylaxis decreases the rate of postoperative VTE compared to short prophylaxis and investigated its association with the occurrence of ICH. Methods Subjects All adult patients who were operated for a HGG (WHO grade III or IV) at University Medical Center Utrecht, The Netherlands, between the 1 st of January 2007 and 30 th of June 2013 were eligible for this study. Exclusion criteria were: age under 18 years at time of surgery and a previous craniotomy. A medical ethics committee stated that the national laws of the medical research human subjects act did not apply to this study because of the retrospective study design; hence, no written informed consent had to be obtained. Outcomes The primary outcomes were the occurrence of VTE (within 21 days and 90 days) as well as ICH postoperatively. VTE was defined as clinical symptoms of deep venous thrombosis or pulmonary embolism confirmed by Doppler ultrasonography or CT angiography, respectively. ICH was defined as a postoperative hemorrhage treated by means of surgical evacuation. Because all ICHs occurred in the direct postoperative period, no distinction was made based on the timing of follow-up. Thromboprophylaxis and other covariates Subcutaneous dalteparin (5000 UI per day) was administered according to the surgeon’s preference. In 2010, two neurosurgeons started continuing thromboprophylaxis up to 21 days after surgery. The other surgeons kept administering thromboprophylaxis until discharge from the hospital (0-7 days). This difference in policy was driven by the physician’s preference rather than by patient characteristics. Other variables collected from the electronic health records were gender, age, BMI, prior history of malignancy or VTE, steroid usage, tumor histology, length of hospitalization, extent of resection reported by the neurosurgeon (sub- or gross-total resection), intraoperative functional mapping, operative time, postoperative Karnofsky Performance Scale (KPS) score, postoperative immobility, and adjuvant chemo- and radiotherapy. Postoperative immobility was defined as weakness in a lower limb and/or walking difficulties.