The Oklahoma Thrombotic Thrombocytopenic Purpura-Hemolytic Uremic Syndrome (TTP-HUS) Registry: A community perspective of patients with clinically diagnosed TTP-HUS. George JN, Vesely SK, Terrell DR. Seminars in Hematology 2004;41(1):60-67.

The Oklahoma Thrombotic Thrombocytopenic Purpura-Hemolytic Uremic Syndrome (TTP-HUS) Registry enrolls all consecutive patients for whom plasma exchange (PE) treatment is requested for clinically diagnosed TTP-HUS within a defined geographic region. Within the clinical spectrum of TTP-HUS, the only excluded patients are children with typical diarrhea-positive HUS, since they are managed by supportive care without PE. During 14.5 years, from January 1989 through June 2003, 301 patients were enrolled; follow-up is complete on 300 patients. Clinical categories were designated based on associated conditions and potential etiologies; presenting features and clinical outcomes were defined to allow comparisons between groups. Of the 290 patients enrolled with their first episode of clinically diagnosed TTP-HUS, 18 were categorized as having bloody diarrhea prodrome. The majority of those patients (83%) responded to PE and 13% of the responders experienced an exacerbation (of a continuing episode) of TTP. One-third in the bloody diarrhea group died but none of the surviving patients experienced a relapse (a new episode) of TTP. ADAMTS-13 activity was measured on 142 (88%) of 161 consecutive patients enrolled from 1995 to 2001. Only 13% of all patients, and 33% of patients with idiopathic TTP-HUS, had severe ADAMTS-13 deficiency (<5% activity). Only those in the idiopathic and pregnancy-associated TTP groups had severe ADAMTS-13 deficiency. The presenting features and clinical outcomes of patients with severe ADAMTS-13 deficiency were heterogeneous and not distinct from patients without severe ADAMTS-13 deficiency. These data suggest that severe ADAMTS-13 deficiency does not detect all patients who may be appropriately diagnosed with TTP-HUS and who may respond to PE treatment. The authors conclude that prospective data from consecutive patients are essential to translate new observations on pathogenesis into improved patient care.