Risk of venous thromboembolism among patients with vasculitis: a systematic review and meta-analysis.

To investigate the possible association between systemic vasculitis and risk of venous thromboembolism (VTE), two investigators independently searched published studies indexed in MEDLINE, EMBASE, and the Cochrane database from inception to April 2016 using the terms for each type of vasculitis in conjunction with the terms for venous thromboembolism. The inclusion criteria were as follows: (1) observational studies published as original studies to evaluate the association between vasculitis and VTE, (2) odds ratios, relative risk or hazard ratio or standardized incidence ratio with 95 % confidence intervals (CI) were provided, and (3) participants without vasculitis were used as comparators for cohort studies and cross-sectional studies while participants without VTE were used as comparators for case-control studies. RevMan 5.3 software was used for the data analysis. Point estimates and standard errors were extracted from individual studies and were combined by the generic inverse variance method of DerSimonian and Laird. Seven studies investigating the risk of VTE among patients with systemic vasculitis were identified. At least one study was available for three specific forms of vasculitis (polyarteritis nodosa [PAN], granulomatosis with polyangiitis [GPA], and giant cell arteritis [GCA]). An increased risk of VTE was seen in all three vasculitides (GPA, pooled RR 3.94, 95 % CI 1.11-14.01; PAN, pooled RR 3.00, 95 % CI 2.20-4.09; GCA, pooled RR 2.26, 95 % CI 1.38-3.71). This meta-analysis demonstrates that patients with systemic vasculitis may have a significantly increased risk of VTE.