Point-of-Care Testing Useful for Newborn Sickle Cell Screening

By Will Boggs MD

September 19, 2019

NEW YORK (Reuters Health) - Point-of-care testing is useful for newborn screening for sickle cell disease (SCD) in low-income settings, according to results from an observational study.

"The most interesting thing for me was that the point-of-care test worked better than the laboratory test," Dr. Ofelia A. Alvarez from Mailman Center for Child Development, University of Miami, told Reuters Health by email. "I was expecting similar results but not better results."

Dr. Alvarez and colleagues compared the point-of-care immunoassay Sickle SCAN versus the gold standard laboratory-based testing for newborn screening in Haiti's second-largest city, Cap-Haitien.

Several countries have newborn screening programs for SCD, but Haiti doesn't, the researchers note in Pediatrics, online September 17. Laboratory testing can identify SCD, but tracking and notifying families of children with positive results is problematic in a setting where infrastructure is lacking and follow-up visits may not take place.

Overall, 19.8% of the 2,159 infants tested in the study had abnormal hemoglobin levels. In confirmatory testing, 0.83% had SCD, including 0.60% (13 children) with sickle cell anemia and 0.23% (five children) with hemoglobin SC disease.

Compared with the gold standard HPLC testing, the point-of-care test showed 97% sensitivity, 90% specificity and 93.6% overall accuracy (by AUROC) for diagnosing SCD.

The confirmatory testing rate improved from 75% to 87% after the introduction of point-of-care testing, which was also associated with shorter times to implement penicillin prophylaxis, engage children in health care, and receive pneumococcal vaccine.

"The Sickle SCAN may be useful in the clinic or in an emergency when you want to find out whether a patient has sickle cell disease or you want to counsel parents regarding trait results," Dr. Alvarez said. "All of this may apply to a higher-resource setting."

"I want to concentrate now on making sure newborn screening continues to be sustainable in our program and to extend it to other sites," she said.

"The ability to provide appropriate follow-up care will perhaps be the greatest challenge of point-of-care (POC) testing," the authors of a linked editorial write. "Because POC diagnosis of SCD yields rapid results directly at the time of testing, it is critically important that appropriate services be available regarding the diagnosis and management."

"Particularly for low-resource settings," add Dr. Russell E. Ware of Cincinnati Children's Hospital Medical Center, in Ohio, and Dr. Isaac Odame of the Hospital for Sick Children, in Toronto, Canada, "we suggest it would be advantageous to integrate POC screening into existing immunization programs that deliver a package of services, including breastfeeding and nutritional education settings, in which counseling can also be more effectively delivered."

Dr. Patrick T. McGann, also from Cincinnati Children's Hospital Medical Center, recently reviewed POC devices currently in development. He told Reuters Health by email, "While POC tests are a great advance and will change the diagnostic paradigm for sickle cell disease in limited resource settings, we need to be careful with widespread implementation."

"The new tests (Sickle SCAN and others) appear to be quite good but are not perfect," he said. "It has yet to be determined how to best utilize POC tests for newborn screening. Are they a standalone test? Confirmatory testing is prudent, but does confirmatory testing need to be performed with another methodology? What if there is no other methodology?"

"Overall, the results provide further validation of point-of-care testing, but further implementation studies in limited-resource settings are necessary to determine how POC tests should be employed for newborn screening in these settings," said Dr. McGann, who was not involved in the study.

The research had no commercial funding, and the authors report no financial interest in the test.

SOURCE: https://bit.ly/2mmRkJ1 and https://bit.ly/2lZIhxb

Pediatrics 2019.

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