Accuracy of Immunochromatographic Strip Test for Screening of α-thalassemia 1 Carriers at the Rural Clinical Settings
α-thalassemia 1 gene is the severe form of α-thalassemia. Couples with carrier of this gene are at risk of having hemoglobin Bart’s hydrops fetalis and the mother often suffers from complications such as pre-eclampsia and postpartum hemorrhage. Therefore, the screening of α-thalassemia 1 carrier in pregnant women and their partners is very important. The α-thalassemia immunochromatographic strip test (αTHAL IC strip, i+Med Laboratories Company Limited) might be an alternative tool to identify carriers of α-thalassemia 1 by testing for hemoglobin Bart’s because it is convenient, cheap and less-time consuming. However, the accuracy of this screening method has not been tested in a large-scale at the rural clinical settings as multi-centers. This study aimed to determine the accuracy of αTHAL IC strip for screening α-thalassemia 1 in two protocols. Protocol I, a total of 898 fresh blood samples of pregnant
women and their partners were screened. They were sent to our laboratory for further confirmation by polymerase chain reaction (PCR) technique. Protocol II, a total of 2,027 aged samples with positive results by the screening tests during the national prevention and control program. They were further tested for α-thalassemia 1 carrier with the αTHAL IC strip and DNA analysis at the Regional Health Promotion Centers, Department of Health. The sensitivity, specificity and accuracy of the αTHAL IC strip for screening α-thalassemia 1 carriers by protocol I were 83.3-100%, 72.0-89.9% and 73.2-89.7% respectively, whereas protocol II were 76.2-100%, 68.3-87.2% and 72.2-88.7%, respectively. It was found that the screening by protocol II had higher false negative results than by protocol I. Taken together; the study revealed that the αTHAL IC strip could be used effectively for screening α-thalassemia 1 carriers due to its high accuracy at the rural clinical settings with fresh blood samples. In addition, the protocol with application of the IC strip test after regular MCV/DCIP screening existing could as well help reduce the number of further DNA analysis samples. However, the cost-effectiveness should be further evaluated extensively.
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