Risk of Venous Thrombosis Associated with White Cell Count On Peripheral Blood and Its Interrelationship with Other Environmental Risk Factors

Abstract 1149 Background: Antithrombotic prophylaxis needs to be balanced against bleeding risk. Therefore, risk stratification is useful to identify patients who would benefit most. In this study, we analyzed how VT risk relates to different leukocyte count. We also analyzed the effect of high leukocyte counts in groups with high risk of VT. Methods: In the MEGA case-control study, blood leukocyte count and information on environmental risk factors were collected from 2443 patients with VT and 1459 partner controls. Logistic regression analyses were adjusted for age and sex. Results: Population characteristics are detailed in Table 1. Risk of VT increased for measurements above the 97.5th percentile for total white cells, granulocytes, lymphocytes and monocytes. Adjusted odds ratio, [OR] for 99th percentile was 1.37 (95% confidence interval [CI], 0.73–2.56), 1.48 (95% CI, 0.79–2.77), 1.20 (95% CI, 0.63–2.31) and 1.88 (95% CI, 1.02–3.46), for total white cells, granulocytes lymphocytes and monocytes, respectively, compared to the reference percentile (5th-95th) (Table 2). We also analysed the effect of high leukocyte counts on VT in high risk groups, including surgical patients, hospitalized patients, and patients with cancer. Adjusted OR for high leukocyte counts (white cell, lymphocyte, monocyte or granulocyte counts > 97.5th percentile) was 6.3 (95% CI, 0.84–47.1) for groups who had surgery or were hospitalized and 2.2 (95% CI, 0.6–8.2) for patients with cancer, respectively, compared with cell counts within the percentile between 5th and 97.5th. Conclusions: High blood leukocyte count is associated with increased risk of VT. The risk is further increased in high risk groups. These results may assist in individually tailored thromboprophylaxis in high risk groups. Disclosures: No relevant conflicts of interest to declare.