Effect of plasma exchange on plasma ADAMTS13 metalloprotease activity, inhibitor level, and clinical outcome in patients with idiopathic and nonidiopathic thrombotic thrombocytopenic purpura.
Therapeutic plasma exchange is an effective empiric treatment for thrombotic thrombocytopenic purpura (TTP), but how therapy affects the level of a disintegrin and metalloprotease with thrombospondin type 1 motif 13 (ADAMTS13) or inhibitor has not been reported in many patients. We prospectively analyzed ADAMTS13 activity and inhibitor levels in 37 adults with TTP. ADAMTS13 level at presentation was lower than 5% in 16 of 20 patients with idiopathic TTP and in none of 17 patients with TTP associated with hematopoietic stem cell transplantation, cancer, drugs, or pregnancy (P <.00001). Seven of the 16 patients with ADAMTS13 activity lower than 5% ( approximately 44%) had inhibitors. For 8 patients followed serially with ADAMTS13 activity lower than 5% but no inhibitor at presentation, plasma exchange led to complete clinical remission and a rise in ADAMTS13 level. In contrast, 4 patients with low ADAMTS13 activity but high-titer inhibitor (> 5 units/mL) had neither a rise in ADAMTS13 activity nor a reduction in the inhibitor titer: 3 had recurrent disease and 1 died. Among 17 patients with AD-AMTS13 activity at presentation higher than 25%, 10 died. Mortality rate for idiopathic TTP was 15%, whereas mortality for nonidiopathic TTP was 59% (P <.02). We conclude that assays of ADAMTS13 activity and inhibitors in addition to the clinical categories (idiopathic TTP and nonidiopathic TTP) are predictive of outcome and may be useful to tailor patient treatment.
Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, The University of Pennsylvania School of Medicine, 34th Street and Civic Center Boulevard, ARC 316, Philadelphia, PA 19104, USA. zheng@email.chop.edu
X Long
XL
Zheng
Richard M
RM
Kaufman
Lawrence T
LT
Goodnough
J Evan
JE
Sadler
D051722:ADAM Proteins; D000071120:ADAMTS13 Protein; D000328:Adult; D000368:Aged; D004791:Enzyme Inhibitors / Q000097:blood; D005260:Female; D018380:Hematopoietic Stem Cell Transplantation / Q000009:adverse effects; D006801:Humans; D008297:Male; D008666:Metalloendopeptidases / Q000097:blood* / Q000172:deficiency*; D008875:Middle Aged; D010951:Plasma Exchange; D011247:Pregnancy; D011248:Pregnancy Complications; D011446:Prospective Studies; D011697:Purpura, Thrombotic Thrombocytopenic / Q000209:etiology / Q000378:metabolism* / Q000628:therapy*; D012074:Remission Induction; D016896:Treatment Outcome
D004791:Enzyme Inhibitors; D051722:ADAM Proteins; D008666:Metalloendopeptidases; D000071120:ADAMTS13 Protein; C099604:ADAMTS13 protein, human