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Inexpensive sickle cell diagnostic tool shows perfect accuracy in Uganda
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SAN DIEGO — An inexpensive, easy-to-use diagnostic tool for sickle cell disease showed 100% accuracy among a large cohort of children from Uganda, according to findings presented during the late-breaking abstract session of ASH Annual Meeting and Exposition.
The test — HemoTypeSC (Silver Lake Research Corporation) — only requires a drop of blood and produces results in about 10 minutes.
Diagnosis, prophylaxis, counseling and treatment have dramatically reduced sickle cell disease incidence and mortality in the developing world, but screening for the disease has not been widely implemented in those regions, particularly in sub-Saharan Africa, according to Erik Serrao, PhD, director of business and product development at Silver Lake Research Corp.
“Although this disease is acknowledged as a public health problem by the U.N. and WHO, African governments and ministries of health still largely neglect this disease,” he said during a press conference. “Individuals with this disease are commonly identified only after they die or when they present at the hospital with life-threatening symptoms.”
Further, current diagnostic tools are unsuitable for the developing world for a number of reasons, Serrao said. These included that they are expensive; they require electricity and technology that is largely unavailable in resource-depleted regions; they require a large volume of blood; and because specimens must be shipped away for analysis.
“Often children are not amenable to be screened,” he said. “If they are screened, it is very traumatic for both the mother and the child.”
Thus, researchers sought to develop a low-cost, low-complexity, point-of-care diagnostic test for sickle cell disease.
The HemoTypeSC immunoassay uses monoclonal antibodies to detect HbA, HbS and HbC.
“The test has been shown to be very accurate in newborns,” Serrao said. “It’s an uncomplicated and rapid procedure.”
The cost is less than $2 per test. Administrators learned how to use it by watching a short video. “It’s ideal for Africa and the developing world,” Serrao said.
Serrao and colleagues evaluated the test in a high-prevalence region in Uganda, where approximately 20% of childhood deaths are due to sickle cell disease. The blinded, prospective, diagnostic study included 1,000 children (51% male) aged 5 years or younger. Serrao added that 20% of the cohort was between 1 month and 1 year old.
According to protocols, the researchers used capillary zone electrophoresis as the comparator assay.
Results indicated that in the initial analysis, the HemoTypeSC test matched the comparator in 998 of 1,000 samples screened, for a 99.8% overall accuracy. When the group ultimately analyzed the two discordant results, it was determined that HemoTypeSC made the correct diagnosis. Thus, in the secondary analysis in which the researchers retested discordant results, it was determined that the study assay yielded 100% overall accuracy.
“The significance here is that HemoTypeSC is an accurate, inexpensive, rapid tool that can enable sickle cell disease screening programs across rural areas of Africa and India,” Serrao said. “The test is easy to use, with no reported issues in this study of any difficulty with the protocol or reading the results.”
Serrao added that sickle cell disease screening programs have been shown to be cost-effective in Africa.
“They could actually save significant amounts of money for governments,” he said. “Early screening plus treatment plus counseling can save millions of lives over the coming decades. We’re excited that HemoTypeSC could form an integral part of the beginning of that equation.” – by Rob Volansky
Reference:
Nankanja R, et al. Abstract LBA-3. Presented at: ASH Annual Meeting and Exposition; Dec. 1-4, 2018; San Diego.
Disclosures : Serrao reports employment with Silver Lake Research Corp., which funded the study, approved its design and donated HemoTypeSC tests. The other authors report no relevant financial disclosures.
Perspective
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Mark Crowther, MD, MSc, FRCPC
In the United States, Canada and Europe, patients with sickle cell disease routinely survive into adulthood. With appropriate care both early in their life and through their adult life, many will survive into late adulthood and become elderly.
In Africa, in most countries, particularly in sub-Saharan Africa, it just doesn’t happen. Those patients all die. People who could have survived and become productive members of society just don’t have the opportunity to do so.
The introduction of a simple and easy-to-use, inexpensive test has a humongous potential to improve outcomes for patients. It is important to note that sometimes we introduce testing to developing nations that is impossible to implement. For sickle cell disease, not only is this test simple to implement, but the interventions that would then come out of it are also easy to implement — things like penicillin prophylaxis, which is really inexpensive and can be afforded everywhere, and hydroxyurea, which also can be provided. This test has huge potential.
ASH has sunk a lot of resources over the last 3 to 4 years into sickle cell disease, including helping to work with sickle cell associations from across Africa to develop programs. This test couldn’t come at a better time, because it is a real focus for the society, as well as for the betterment of humankind because of the number of patients who have this disorder.
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