Clinical Features of Severe Acquired ADAMTS13 Deficiency in Thrombotic Thrombocytopenic Purpura: Second Report of the Korean TTP Registry.

Abstract 2188

The clinical utility of ADAMTS13 activity for TTP has been extensively studied for last years. However, the clinical significance of ADAMTS13 activity for response to treatment, mortality rate, recurrence, and prognosis is still unclear. We previously reported the characteristics of severe ADAMTS13 deficiency in thrombotic thrombocytopenic purpura (TTP) and patients with severe ADAMTS13 deficiency had lower serum creatinine levels than patients with non-severe ADAMTS13 deficiency using 66 patients enrolled from January 2005 to December 2008. (Jang MJ et al, Int J Hematol 2011;93:163–9). In this second report, we enrolled 65 additional patients from January 2009 to June 2012 and analyzed 131 TTP patients using same methods. Patients with severe ADAMTS13 deficiency had lower serum creatinine levels (P=0.001), lower platelet counts (P<0.0001), and high total bilirubin levels (P=0.018) at presentation. However, as same as previous results, treatment outcomes did not differ significantly between severe and non-severe ADAMTS13 deficiency groups in response rate (82 vs. 65%, P = 0.256), remission rate (70 vs. 63%, P = 0.781), and mortality rate (23 vs. 18%, P = 0.820). After adjusting for clinical and laboratory features, multivariate analysis did not reveal any independent risk factors for TTP-associated mortality. In conclusion, although TTP with severe ADAMTS13 deficiency is a unique subgroup characterized by lower platelet count and relatively good renal function, the prognostic significance of ADAMTS13 is still unclear and further study would be required to clarify it.