By Ian Ingram, Deputy Managing Editor, MedPage Today - December 04, 2018
SAN DIEGO -- An inexpensive, easy-to-use blood test could dramatically alter how sickle cell disease is diagnosed in Africa, where the often-undiagnosed disease is a leading cause of childhood mortality, according to a manufacturer-sponsored study presented here.
Using a single drop of blood, the HemoTypeSC test accurately diagnosed sickle cell disease in 998 of 1,000 children in Uganda, reported Erik Serrao, PhD, of Silver Lake Research Corp. in Azusa, California.
With an end-user cost of $2, the test requires no electricity and can be used without special equipment or highly specialized training, noted session moderator Mark Crowther, MD, of McMaster University in Hamilton, Ontario.
"The current gold standard for diagnosing sickle cell disease is challenging, or in fact frankly impossible, in many low-resource settings due to the cost and requirement for sophisticated equipment and reliable electricity," said Crowther. "Of all the late-breaking abstracts, this one is the one that has the potential to save the most lives."
He said the test has "humongous potential" to improve outcomes.
"Sometimes we introduce testing to the third world, or the developing nations, which are impossible to implement," Crowther said. "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."
Results from HemoTypeSC were returned within 10 minutes and delivered at the point of care, and the test was found to be highly specific for HbA, HbS, and HbC abnormal hemoglobins. Silver Lake Research says the dipstick-type test can also be used with dried blood spots.
Serrao said that even in certain low-resource areas of the U.S., population-based screening with an inexpensive test could be of benefit, as some adults -- "lucky enough to have survived" -- may not know they have sickle cell disease. (The product is approved in Europe but remains investigational in the U.S.)
Crowther added that other potential applications for developed countries could be in circumstances where a patient's sickle cell disease status is unknown or cannot be reported or easily determined, such as an individual involved in a car accident -- "people present to the emergency department, it's 2 o'clock in the morning, you can't track down their medical records."
For those with a suggestive history of sickle cell disease, having a $2 test could have "real potential" to improve the quality of care, he said.
The study was conducted at the Jinja Regional Referral Hospital in southeastern Uganda, where sickle cell disease accounts for roughly one-fifth of childhood deaths each year. During the trial, there were no reported issues with either the study protocol or reading the results.
Most of the children (84.5%) were 5 years of age and below and were relatively evenly split by year of age -- 19.7% were in the 1 month to 1 year range and 24.9% were in the 1 to 2 year range. Patients were also evenly split between boys (51%) and girls (49%).
The test matched the reference test for all 720 HbAA specimens, and of the remaining 280 HbAS and HbSS specimens, there were two discordant results for an overall accuracy of 99.8%. But the two samples were retested with another reference method, and this secondary analysis revealed the HemoTypeSC test to have correctly diagnosed these cases.
Serrao noted that one limitation of the study was that the test was not used on newborns, but a recent study in the American Journal of Hematology confirmed HemoTypeSC in this setting (n=57) with 100% accuracy.