In the wake of a lead contamination crisis affecting cities across the country, the US Food and Drug Administration (FDA) on Wednesday warned that a commonly used line of lead testing systems may provide falsely low results under certain circumstances.
According to FDA, all four of Magellan Diagnostics' LeadCare testing systems may provide inaccurate results when testing blood drawn from a patient's vein. However, the agency says it does not have reason to believe the tests are inaccurate when done with capillary blood taken from a patients' finger or heel.
FDA cleared the first of Magellan's LeadCare diagnostics in 1997, and has cleared three subsequent versions—LeadCare II in 2005, LeadCare Ultra in 2013 and LeadCare Plus in 2015—for use in different settings.
Jeffrey Shuren, director of FDA's Center for Devices and Radiological Health (CDRH), said that most patients won't be affected the issue, as the majority of lead testing is done using capillary blood, and about half of all tests are processed using other unaffected methods, such as graphite furnace atomic absorption spectroscopy (GFAAS).
While Shuren said the LeadCare systems may have been used for 8 million tests since 2014, Patrick Breysse, director of the National Center for Environmental Health at the Centers for Disease Control and Prevention (CDC) said that at least in Flint, Michigan, less than 1% of children tested since 2016 are at risk for false results.
Nevertheless, CDC is recommending that children under the age of six, as well as pregnant or nursing women, that were tested with any of Magellan's LeadCare systems using blood drawn from a vein that received results of less than 10 micrograms per deciliter (µg/dL) be retested for lead exposure using an alternative method.
FDA's diagnostic review team first learned of the potentially inaccurate results when reviewing a 510(k) submission for a new version of the LeadCare system earlier this year, Shuren said.
However, Shuren said Magellan was aware of the issue as early as August 2014, when it received complaints from customers about the accuracy of the tests. At the time, the company looked into the issue and determined the risk for inaccurate results could be mitigated by delaying processing of the test for 24 hours.
"It wasn't until we started to ask more questions of the company—starting to peel back the onion—that we found that the company had underestimated the amount of risk to the public and that they did not have adequate data and supporting documentation regarding the cause of the problem or the effectiveness of the mitigation that they had put in place in the past," Shuren said.
Shuren added that the issues weren't caught during the agency's review of the LeadCare Plus in 2015, as the company did not convey information about the risk to FDA during that review.
In response, Shuren said FDA is issuing a Class I recall for the tests and that FDA investigators are on site at Magellan to look into the matter.
But Shuren said the investigation is still in its early stages and the agency has not determined the root cause of the inaccurate results.
"There may be differences in how the blood is collected, the tubes that may be used for it, or some of the other processing, and that may account for why there are differences," he said.
FDA Safety Communication, Press Release, CDC