ABO blood group type and risk of venous thromboembolism in patients with cancer

Abstract

Abstract Venous thromboembolism (VTE) is common in patients with cancer. Although in the general population blood type non-O is associated with increased VTE risk, the impact of ABO blood type on risk of cancer-associated VTE has not been clarified. To determine the influence of ABO blood type on cancer-associated VTE risk, we conducted an analysis within the Vienna Cancer and Thrombosis Study, a prospective cohort study including patients with newly diagnosed or recurrent cancer observed for the primary outcome VTE. Restricted cubic spline analysis was performed and specific time-restricted subdistribution hazard ratios (SHR) were calculated to investigate the association between non-O blood type and VTE over time. One thousand, seven hundred and eight patients were included in the analysis (median follow-up time: 24 months; interquartile range: 10-24), and 151 patients developed VTE (8.8%). During the first 3 months of follow-up, there was no association between non-O blood type and VTE risk (SHR: 1.00; 95% confidence interval [CI]: 0.60-1.67). Thereafter, non-O blood type was associated with a higher VTE risk (SHR: 1.79; 95% CI: 1.12-2.85). Furthermore, non-O blood type was associated with increased VTE risk in patients with intermediate and low thrombotic risk tumor types (SHR: 1.73; 95% CI: 1.09-2.73) but not in very high-risk types (pancreatic, gastroesophageal, and brain cancer; SHR: 0.94; 95% CI: 0.55-1.61). This association was weakened after adjustment for factor VIII. Non-O blood type is a time-dependent predictor of VTE in patients with cancer. It is associated with increased VTE risk beyond 3 months of follow-up and in patients with intermediate- and low-risk tumor types.