The incidence of thrombotic thrombocytopenic purpura-hemolytic uremic syndrome: all patients, idiopathic patients, and patients with severe ADAMTS-13 deficiency.
BACKGROUND
Accurate estimates of the incidence of thrombotic thrombocytopenic purpura (TTP) are important to assess the resources required for current treatments as well as to anticipate the need to develop new treatments. Previous estimates have been indirect and have not reported data on patients with ADAMTS-13 deficiency.


OBJECTIVE
To determine the incidence of patients with TTP-hemolytic uremic syndrome (HUS) in three categories: all patients with clinically suspected TTP-HUS, patients with idiopathic TTP-HUS, and patients with severe ADAMTS-13 deficiency.


METHODS
Incidence rates were estimated from the Oklahoma TTP-HUS Registry, analyzing all 206 consecutive patients from January 1, 1996 to June 30, 2004 who were treated with plasma exchange for their initial episode of clinically suspected TTP-HUS. ADAMTS-13 activity was measured in 186 (90%) of the 206 patients.


RESULTS
The age-sex-race standardized annual incidence rates were 11.29 x 10(6) (95% CI: 9.70-12.88) for all patients with clinically suspected TTP-HUS; 4.46 x 10(6) (95% CI: 3.43-5.50) for patients with idiopathic TTP-HUS; and 1.74 x 10(6) (95% CI: 1.06-2.41) for patients with severe ADAMTS-13 deficiency (<5% activity). In all three categories, the incidence rates were greater for women and for blacks. For patients with severe ADAMTS-13 deficiency, the age-sex standardized incidence rate ratio of blacks to non-blacks was 9.29 (95% CI: 4.33-19.93).


CONCLUSIONS
Accurate incidence rate estimates for all patients with clinically suspected TTP-HUS, idiopathic TTP-HUS, and TTP associated with severe ADAMTS-13 deficiency have been determined. The greater incidence among women and blacks is comparable with their increased risk for other autoimmune disorders.
Hematology-Oncology Section, Department of Medicine, College of Medicine, The University of Oklahoma Health Sciences Center, Oklahoma City, OK 73190, USA.
D R
DR
Terrell
L A
LA
Williams
S K
SK
Vesely
B
B
Lämmle
J A K
JA
Hovinga
J N
JN
George
D051722:ADAM Proteins; D000071120:ADAMTS13 Protein; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001327:Autoimmune Diseases / Q000453:epidemiology; D044383:Black People; D002648:Child; D002675:Child, Preschool; D005260:Female; D006463:Hemolytic-Uremic Syndrome / Q000097:blood / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008666:Metalloendopeptidases / Q000172:deficiency*; D008875:Middle Aged; D010951:Plasma Exchange; D011247:Pregnancy; D011250:Pregnancy Complications, Hematologic; D011697:Purpura, Thrombotic Thrombocytopenic / Q000097:blood / Q000453:epidemiology*; D012042:Registries; D044465:White People
D051722:ADAM Proteins; D008666:Metalloendopeptidases; D000071120:ADAMTS13 Protein; C099604:ADAMTS13 protein, human