Joeky Senders

60 Chapter 3 Limitations Complication rates found in the current study can be conservative estimates if events were not reported back to the hospitals. VTEs were only coded as events if they were diagnosed and treated, thereby missing asymptomatic and undetected VTEs. Tumor specific information (histology, size, location, residual tumor volume) and complication specific information (location and classification of DVT, PE, and ICH) was not available. However, both VTE and ICH were defined in the NSQIP database as complications requiring medical and surgical treatment, respectively, resulting in selection of the most clinically relevant events. Perhaps most importantly, no data is available regarding the use of thromboprophylaxis and non-pharmaceutical prophylactic strategies. Therefore, this study offers limited insight into the efficacy of different thromboprophylactic treatment strategies and their association with the occurrence of ICH. Selection bias can be introduced since institutions can selectively contribute patients to the NSQIP registry. Stratifying the analyses based on VTE type and clinical setting reduced the number of events per outcome measure. Yet, our study was not underpowered for most outcome measures according to rule of ten events per variable in the multivariable analysis. 52 Lastly, VTE and ICH events after the 30-day time period established in NSQIP are not accounted for in this study, whereas studies have demonstrated that the risk of VTE events remains non-negligible beyond 30 days postoperatively with incidences up to 26% in the first 12 months postoperatively. 4-6 Despite these limitations, this study provides useful insight into the rates, timing, and predictors of DVT, PE, and ICH after craniotomy for a primary malignant brain tumor. Due to the multicenter nature of the NSQIP dataset, the results of this study may be more representative of typical management at all hospitals, including but not limited to tertiary care academic centers. Implications The significant prevalence of VTE and ICH following craniotomy for primary malignant brain tumors found in the current study indicates that there is still roomfor improvement when it comes to monitoring and preventing these events. These results particularly encourage the need for continued awareness for VTE post- discharge, and PE in particular. These PEs can also be considered more sudden since they were less often preceded by a detected DVT. PEs preceded by a DVT, however, suggest inadequate treatment of the initial DVT event. It is possible that PE are less frequently preceded by a DVT after discharge. It is our primary suspicion, however, that DVTs remain undetected more frequently after leaving the hospital because they are less frequently symptomatic and cannot be effectively screened for. It is also possible