Objective: Patients with giant cell arteritis (GCA) may have an increased risk of pulmonary embolism (PE), similar to other systemic vasculitidies; however, no relevant population data are available to date. Objective: To evaluate the future risk and time trends of new venous thromboembolism (VTE) in individuals with incident GCA at the general population level.

Methods: Observational cohort study. Methods: General population of British Columbia. Methods: 909 patients with incident GCA and 9288 age-matched, sex-matched and entry-time-matched control patients without a history of VTE. Methods: We calculated incidence rate ratios (IRR) overall, and stratified by GCA duration. We calculated HR of PE and deep vein thrombosis (DVT), adjusting for potential VTE risk factors.

Results: Among 909 individuals with GCA (mean age 76 years, 73% women), 18 developed PE and 20 developed DVT. Incidence rates (IR) of VTE, PE and DVT were 13.3, 7.7 and 8.5 per 1000 person-years (PY) in GCA cohort, versus 3.7, 1.9 and 2.2 per 1000 PY in the comparison cohort. The corresponding IRRs (95% CI) for VTE, PE and DVT were 3.58 (2.33 to 5.34), 3.98 (2.22 to 6.81) and 3.82 (2.21 to 6.34) with the highest IRR observed in the first year of GCA diagnosis (7.03, 7.23 and 7.85, respectively). Corresponding fully adjusted HRs (95% CI) were 2.49 (1.45 to 4.30), 2.71 (1.32 to 5.56) and 2.78 (1.39 to 5.54).

Conclusions: These findings provide general population-based evidence that patients with GCA have an increased risk of VTE, calling for increased vigilance in preventing this serious, but preventable complication, especially within months after GCA diagnosis.