Efficiency assessment of immunochromatographic strip test for the diagnosis of alpha-thalassemia-1 carriers.

Context: The prevention and control of thalassemia in Thailand focus on the appropriate diagnosis with a simple, cheap, and practical tool for any staff to use.

Aims: (1) To screen alpha-thalassemia-1 carriers among pregnant women and spouses by immunochromatographic (IC) strip test and one tube osmotic fragility test (OFT) and (2) to evaluate the accuracy of both screening methods.

Setting And Design: Cross-sectional study for 6 months duration from January to June 2013 at Kudjab Hospital located in Udonthani Province, Thailand.

Subjects And Methods: Pregnant women and spouses attending the antenatal care clinic joined the study for blood sample collection (n = 414). The specimens were then taken for screening by osmotic fragility and IC strip test to specify alpha-thalassemia carriers. Another set of the specimens was sent for testing using hemoglobin (Hb) typing for thalassemia and abnormal Hb carriers and using multiplex polymerase chain reaction for alpha-thalassemia-1 carriers diagnosis as a gold standard.

Results: There were 27 cases found as positive for alpha-thalassemia including alpha-thalassemia-1 carriers, South East Asian type, alpha-thalassemia-1 carriers, Thai deletion type, HbH and Hb constant spring, which were 18, 2, 3, and 2 cases, respectively. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of IC strip test were 92.6%, 95.1%, 56.8%, 99.4%, and 94.9%, respectively, which were higher than those of OFT.

Conclusions: Accuracy of IC strip test was better than those of OFT. IC strip test may probably be very helpful in a massive thalassemia screening program.