Preliminary laboratory based diagnostic criteria for immune thrombocytopenic purpura: evaluation by multi-center prospective study.
BACKGROUND
We proposed diagnostic criteria for immune thrombocytopenic purpura (ITP) by modifying the existing guidelines for diagnosis of ITP and by incorporating laboratory tests found useful for predicting its diagnosis, for example erythrocyte count, leukocyte count, anti-GPIIb/IIIa antibody-producing B cells, platelet-associated anti-GPIIb/IIIa antibodies, percentage of reticulated platelets, and plasma thrombopoietin.


OBJECTIVE
To validate our criteria, we conducted a multi-center prospective study involving 112 patients with thrombocytopenia and a morphologically normal peripheral blood film at the first visit. Each patient underwent a physical examination, routine laboratory tests, and specialized tests for the anti-GPIIb/IIIa antibody response and platelet turnover.


RESULTS
Ninety-one patients (81%) satisfied the proposed criteria at first visit. Clinical diagnosis was made by skilled hematologists > 6 months after the first visit; ITP was diagnosed in 88 patients and non-ITP disorders in 24. The proposed criteria had 98% sensitivity, 79% specificity, a 95% positive predictive value, and a 90% negative predictive value. A relatively low specificity appears to be attributed to a few patients who had both ITP and aplastic anemia or myelodysplastic syndrome.


CONCLUSIONS
Our preliminary diagnostic criteria based on ITP-associated laboratory findings were useful for the differential diagnosis of ITP, but additional evaluations and modifications will be necessary to develop criteria that can be used routinely.
Kuwana
M
M
Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan. kuwanam@sc.itc.keio.ac.jp
Kurata
Y
Y
Fujimura
K
K
Fujisawa
K
K
Wada
H
H
Nagasawa
T
T
Nomura
S
S
Kojima
T
T
Yagi
H
H
Ikeda
Y
Y
D000293:Adolescent; D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000097:blood; D001772:Blood Cell Count; D001792:Blood Platelets / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D019411:Clinical Laboratory Techniques / Q000592:standards; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000276:immunology; D017410:Practice Guidelines as Topic; D011237:Predictive Value of Tests; D011446:Prospective Studies; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000175:diagnosis*; D012680:Sensitivity and Specificity
D001323:Autoantibodies; D019039:Platelet Glycoprotein GPIIb-IIIa Complex