High rates of venous thromboembolic events in patients undergoing systemic therapy for urothelial carcinoma: A systematic review and meta-analysis

Background: Patients undergoing systemic therapy for urothelial carcinoma (UC) are at increased risk for venous thromboembolic (VTE) events. The objective of the current study was to determine the rate of VTE events in patients undergoing systemic therapy for UC and assess factors affecting this rate. Methods: This study was registered with the PROSPERO database (CRD42015025774). We searched Pubmed, MEDLINE, EMBASE, The Cochrane Library, CINAHL, and Web of Science libraries through August 2014. As per PRISMA guidelines, 2 reviewers independently reviewed titles and abstracts. Disagreements were arbitrated by a third reviewer. After full text review, data were abstracted and pooled using a random effects model. Authors were contacted for clarification of data. To determine VTE risk factors, subgroup analyses and meta regression were conducted. Results: We identified 3,635 publications in the initial search, of which 410 met inclusion criteria for full text review. Of these, we were able to obtain data on the outcome of interest for 62 publications. A total of 5,082 patients, of which 77% were male, underwent systemic therapy for UC, with 373 VTE events. The proportion of patients who had had prior surgery, chemotherapy, or radiation was 55%, 25%, and 9%, respectively. Fixed effects and random effects models were used to estimate the VTE rate, yielding event rates of 6.7% and 5.4%, respectively. Conclusions: VTE occurs frequently in patients undergoing systemic therapy for UC. The VTE rate was affected by the country of origin, history of radiation, as well as by the systemic treatment class. The study was limited by the incomplete reporting of all variables of interest. (C) 2016 Elsevier Inc. All rights reserved.