Evaluation of an immunochromatographic test for alpha thalassaemia screening in a multi‐ethnic population

Abstract

Introduction The standard screening method for alpha thalassaemia is the examination of HbH preparation. It is labour intensive and poorly standardized. The development of a rapid strip immunochromatographic test (ICT) for haemoglobin Barts offers a fast, user friendly and cost‐effective alternative screening tool. Method A total of 180 subjects with results of the thalassaemia screen and genetic testing were included. Results of the ICT and HbH preparation were correlated with genetic results to determine the performance characteristics of the tests and the effect of mean sample age on results. Results Of 180 subjects, 111 carried alpha thalassaemia mutations and 69 participants had normal genetic results. The ICT had a sensitivity of 63.06% for all alpha gene mutations and 100% for both heterozygous alpha0 and HbH disease, with a specificity of 91.30%. Examination of HbH preparation had a sensitivity of 34.23% overall, detecting 89% of heterozygous alpha0 and 100% of HbH disease with a specificity of 98.55%. Sample age did not affect overall results. Conclusions The ICT is a sensitive screening method for significant alpha mutations and detects the majority of homozygous alpha+ and nondeletional mutations. It demonstrates greater correlation with genetic testing than HbH preparation and could replace HbH preparation in the screening algorithm for alpha thalassaemia.

False positive Hb Bart's immunochromatographic strip test for alpha thalassaemia in delta‐beta thalassaemia carriers

“…3 Compared to the conventional red cell Hb H-inclusion test commonly used in phenotypic haemoglobinopathy testing, AT-ICT has improved overall sensitivity of 63%-76% (alpha-zero 97%-100%, alpha-plus 44%-70%) and specificity of 91%-100% for alpha thalassaemia detection. [4][5][6] It has the advantages of fast turnaround time, requiring no special equipment or technical expertise and lower operator cost.The AT-ICT results, however, can be falsely positive in newborn babies when the Hb F levels are high. 5 Occasional false positive results have also been reported in other haemoglobinopathy conditions, mainly in Hb E, Hb S and beta thalassaemia conditions.…”

“…5 Occasional false positive results have also been reported in other haemoglobinopathy conditions, mainly in Hb E, Hb S and beta thalassaemia conditions. 4,6…”

“…3 Compared to the conventional red cell Hb H-inclusion test commonly used in phenotypic haemoglobinopathy testing, AT-ICT has improved overall sensitivity of 63%-76% (alpha-zero 97%-100%, alpha-plus 44%-70%) and specificity of 91%-100% for alpha thalassaemia detection. [4][5][6] It has the advantages of fast turnaround time, requiring no special equipment or technical expertise and lower operator cost.…”

Hb Bart's immunochromatographic test result and Hb F level in normal cord blood and in selected haemoglobinopathy cases

“…2 Occasional false positive results have also been reported in other haemoglobinopathy disorders, including Hb E and beta thalassaemia conditions. 3,4 There is no published study correlating the false positive AT-ICT result with Hb F level. The package insert indicates the test is unsuitable for cord blood or newborn samples, but there is no advice on the age when the test can start to be used for alpha thalassaemia detection.…”