Evaluation of an immunochromatographic strip test for alpha-thalassaemia screening.

INTRODUCTION

Hb H inclusion test (HbH-i) commonly used for α-thalassaemia screening is not standardised and is labour-intensive. This study evaluated a strip test based on immunochromatographic detection of Hb Bart's (ICT) for use as a routine screening test for α-thalassaemia screening in the clinical laboratory setting.

METHODS

The performance characteristics of the ICT was determined by comparing the results of ICT and HbH-i on 67 patients, and the α-globin genotype on 47 of these patients who also had the molecular analysis. Specimen stability was tested on 16 specimens with the ICT repeated after 7 days of storage. The age of babies from which the ICT result becomes valid was determined on 49 samples with patient age ranged from 4 weeks to 12 months.

RESULTS

The ICT had higher overall sensitivity of 76% compared to 24% for HbH-i in detecting carriers of α-thalassaemia mutations, and this is seen in all α-thalassaemia genotypes. The test could be carried out on specimens stored at 4°C for 7 days and gave valid results with no false positive from the age of 6 months onwards. It required no special technical expertise or equipment and gave the result in less than 5 minutes.

CONCLUSION

The ICT is simple to perform, with higher sensitivity than HbH-i, and gives the result in a short time and at a lower cost. This can be used by clinical laboratories to replace HbH-i for α-thalassaemia detection.