Evaluation of the Thalassemia and Hemoglobin E Screening in Community Hospitals

Abstract

The  purpose  of this retrospective  descriptive  study was  to evaluate the use of mean

corpuscular volume (MCV)   values less than 80 fL  and mean corpuscular hemoglobin (MCH)

values  less  than  27  pg  combined  with  the  dichlorophenolindophenol  test (DCIP   test) in  a

national screening protocol for thalassemia and hemoglobin E (Hb E) screening  of pregnant

women and their partners in community hospitals. The interpreted results were compared with

the results obtained from Hb typing and DNA  analysis for  α0-thalassemia and β-thalassemia

as gold standard. Study participants consisted of 7,615 Thai pregnant women and their partners

who  were  positive on the preliminary  screening  and attending antenatal care services in 63

community  hospitals of the 4 provinces;  Nakhon Ratchasima,  Chaiyaphum,  Buriram,  and Surin.

The  7,615  blood samples were initially  screened for  α0-thalassemia and  β-thalassemia by

using 9 different hematology analyzers. A  total of  6,382  blood  samples  were  tested for  the

presence of Hb E by using DCIP  kit. The screening results were compared with the results of

Hb typing and DNA analysis. The study reveals that the Coulter DxH500, Coulter LH780, Dirui

BF  6800, Pentra ES60,  Pentra XL80,  Cell-Dyn  Ruby, Sysmex XN-1000i,  and Sysmex XS-800i

could  be used to detect  α0-thalassemia and  β-thalassemia with the reference cutoff values of

MCV   < 80 fL and MCH  < 27 pg, but only one sample of β+-thalassemia with MCV   > 80 fL and

MCH  > 27 pg was detected by Mindray  BC6800.   However,  this did not indicate that the cutoff

values of MCV<  80 fL  and MCH  < 27 pg were not suitable for Mindray  BC6800   as only one

sample might not represent  significant  data. Hb  E screening with DCIP   test revealed 93.8%

positive predictive value, 83.2% negative predictive value and 89.5% accuracy. It was also found

that the factors  affecting  the misinterpretation  were the lacking  of knowledge  and interpretation

skill  of laboratory personnel and insufficiency of quality control systems of the laboratories.

Based on these results, using the combined test of blood indices and Hb E screening for pregnant

women and their partners following the national screening protocol, all clinical  laboratories

should be concerned over false negative results and the proper quality control system. Moreover, personnel who are responsible for the screening  should get a competent training.