Immune thrombocytopenia increases the risk of thrombosis: A two-sample Mendelian randomization study

Immune thrombocytopenia (ITP) is a prevalent autoimmune bleeding disorder, with the primary objective of treatment being the prevention of bleeding. Clinical investigations have indicated that individuals with ITP face an elevated risk of thrombosis, and the occurrence of thromboembolic events in ITP patients can be attributed to a multitude of factors. However, establishing a definitive causal relationship between ITP and thrombosis remains challenging.

A two-sample Mendelian randomization (MR) study utilizing summary data from FinnGen consortium and UK Biobank was undertaken to investigate the causal association between ITP and thrombosis. The primary analysis employed the inverse-variance weighted (IVW) method, while supplementary analyses were conducted using the MR-Egger, weighted median, and MR-PRESSO approaches.

Based on IVW method, there was a statistically significant but small positive correlation between ITP and thrombosis. Specifically, ITP patients exhibited a suggestive positive correlation with myocardial infarction and deep-vein thrombosis. However, our investigation did not identify any causal relationship between ITP and cerebral infarction, arterial embolism, other arterial embolisms, pulmonary embolism, thrombophlebitis, or portal vein thrombosis. Sensitivity analyses further confirmed the accuracy and robustness of these findings.

This study presents empirical support for the causal relationship between ITP and thrombosis. It is important to note that a diminished platelet count does not serve as a preventive measure against thrombus formation. Consequently, when managing a newly diagnosed ITP patient, clinicians need to be aware that there is a slight elevation in the risk of thrombosis during treatment.