What is the effect of complement inhibition therapy on thromboembolic complications in paroxysmal nocturnal hemoglobinuria (PNH)?

Updated: May 20, 2021
  • Author: Emmanuel C Besa, MD; Chief Editor: Sara J Grethlein, MD, FACP  more...
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Answer

Complement inhibitor treatment reduces the risk of clinical thromboembolism in patients with PNH (the leading cause of death in PNH) and is recommended for PNH patients with a history of prior thromboembolism. [53] The rate of thrombotic complications prior to eculizumab was 5.6 per 100 patient years; after eculizumab, it dropped to 0.8 per 100 patient years.

In an international multi-institutional cooperative study involving 195 PNH patients, the thromboembolic (TE) event rate per 100 patient-years with eculizumab treatment was 1.07, compared with 7.37 events (P < 0.001) prior to eculizumab treatment, a relative absolute reduction of 85%. With equalization of duration of exposure before and during treatment for each patient, TE events were reduced from 39 before eculizumab to 3 during eculizumab (P < 0.001). The TE event rate in antithrombotic-treated patients (n = 103) was reduced from 10.61 to 0.62 events/100 patient-years with eculizumab treatment (P < 0.001).

One study has documented elevated D-dimer levels in PNH patients with a history of thrombosis. D-dimer levels decreased immediately after initiation of eculizumab therapy. [54]

Continuation of anticoagulation in patients with PNH with a previous thrombosis while on eculizumab is recommended, as stopping therapy has not been studied. However, patients with no previous thrombosis have discontinued warfarin after starting eculizumab, with no thrombotic sequelae. [52, 55]


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