Predicting Outcomes in Patients with Thrombotic Thrombocytopenic Purpura

Thrombotic thrombocytopenic purpura (TTP) is a microvascular occlusive syndrome characterized by widespread platelet-fibrin thrombi, the formation of which is mediated by large multimers of von Willebrand factor (vWF). In some patients with TTP, levels of ADAMTS13 — a metalloproteinase that cleaves vWF multimers — are extremely low. Can measurement of ADAMTS13 levels predict outcomes in patients with TTP?

To address this question, investigators analyzed data collected during 20 years in the Oklahoma TTP Registry. ADAMTS13 levels were measured at initial diagnosis in 261 TTP patients; 23% of these patients had ADAMTS13 activity levels <10% of normal (“low levels”). Low ADAMTS13 levels did not predict death from any cause: 78% of patients with…