Patients with thrombotic thrombocytopenic purpura (TTP) may be at higher risk of venous thromboembolism (VTE), necessitating VTE thromboprophylaxis earlier for hospitalized patients with TTP, according to research published in the Journal of Thrombosis and Haemostasis.
Arterial thromboembolic events are relatively common in patients with TTP, but data on VTE are much less common. Plasma exchange (PLEX) is a common treatment for acquired TTP but it may put patients at higher risk of developing VTE.
The study authors retrospectively reviewed charts of patients with acute TTP in a tertiary care hospital to describe the point prevalence of VTE. They included 77 patients who were part of the institution’s registry of people treated for TTP and other thrombotic microangiopathies.
The study included 14 patients who were diagnosed with 16 VTEs (18%), including pulmonary emboli (PE), deep vein thrombosis (DVT), and superficial vein thrombosis (SVT). Of the VTEs, 81% were symptomatic. All patients received PLEX treatment, and VTE occurred a median of 13.5 days after the first PLEX treatment, after platelet count and hemolytic marker normalization.
The authors also examined risk factors for VTE and prophylaxis. Prior studies have found that obesity, immobility, surgery, cancer, and prior history of VTE raise the risk of VTE.
In this study, patients who had VTE were found to have a slightly higher median BMI than those who did not have VTE (29.7 vs 26), but the difference was not significant. Most patients did not receive thromboprophylaxis before being diagnosed with VTE.
Red blood cell transfusion did not appear to pose an increased risk of VTE in this study population, although it has been suggested as a risk factor in other studies. Patients who received solvent-detergent plasma had higher rates of VTE than the general population with TTP (75% vs 41%).
The authors concluded that TTP-specific guidelines are needed for thromboprophylaxis, but patients with TTP should receive prophylaxis based on current recommendations for thrombocytopenic patients. The current recommendation is to initiate treatment when the platelet count is more than 50 × 109 U/L.
Disclosures: Some authors have declared affiliations with or received grant support from the pharmaceutical industry. Please refer to the original study for a full list of disclosures.
Tse B, Lim G, Sholzberg M, Pavenski K. Describing the point prevalence and characteristics of venous thromboembolism in patients with thrombotic thrombocytopenic purpura. J Thromb Haemost. 2020;18(11):2870-2877. doi:10.1111/jth.15027