Joeky Senders

52 Chapter 3 A p-value below 0.05 was considered statistically significant. Bonferroni correction for multiple testing was deemed to be too rigorous due to the low number of events. The β-coefficients of the continuous variables in the final model were multiplied to represent the odds ratios and confidence intervals of meaningful and interpretable units for age (per ten years increase), BMI (per five kg/m2 increase), and operative time (per 60 minutes increase). Results Demographics of study population The NSQIP registry provided 7376 patients who underwent craniotomy for resection of a primary malignant brain tumor during the study period. Comorbidities, demographics, and preoperative laboratory values are shown separated by the occurrence of VTE (Table 1). Outcomes Of the 7376 patients that were identified, 257 (3.5%) developed a VTE within 30 days after surgery, of which 91 (36%) occurred within the initial hospital stay. VTE was the second-most common major complication and included 192 DVTs (2.6%) and 107 PEs (1.5%). Forty-two patients developed both DVT and PE (0.6%). The rate of DVT was highest within the first two weeks after surgery, whereas the rate of PE was fairly consistent throughout the first month, occurring predominantly post-discharge (Fig. 1a, Fig. 1b). The rate of VTE was more than twice as high (7.0% versus 3.2%, p < 0.001) among patients with a preoperative dependent functional status compared to patients with an independent functional status (Fig. 1c). The median length of stay among VTE patients was eight days (inter-quartile range [IQR] 5-16 days) compared to four days (IQR 3-8 days) in non-VTE patients (Fig. 1d). In- hospital VTE occurred at a median of six days (IQR 3-8 days) after surgery, and patients were discharged at a median of eight days after the occurrence of VTE (IQR 3-16 days). Post-discharge VTE occurred at a median of 13 days after discharge (IQR 6-19 days) and resulted in 25% of cases in readmission, making VTE the third-most common reason for readmission (7.4% of total readmissions). Of the patients that developed a PE, 35 (32.7%) were preceded by a DVT. Post-discharge PEs were less frequently preceded by a DVT than hospital acquired PEs (26% vs. 48%, p=0.048).