“Although this study shows promise … to accurately identify Lyme arthritis with the use of the C6 EIA test, it is not clear what the false negative rate was,” she tells Reuters Health by email. “Their numbers show that they were able to diagnose 23.2% of children with Lyme arthritis and 1.2% with septic arthritis. But 75.6% were identified as having inflammatory arthritis, which means that the diagnosis is unclear. Based on the published false negative rate of this test, we can assume that a fair percentage of those with inflammatory arthritis probably had Lyme arthritis.”
“One key point is that the study design included a confirmatory immunoblot test for C6 EAI positive or equivocal results. This would be equivalent to a two-tier test,” she says. However, “no immunoblot testing was done on any of the C6 EAI- negative results. Since we we know a large number of patients will be missed by this (test), it is discouraging to think of all those patients who might still be suffering with Lyme disease that was undetected with the screening C6 EAI test.”
“There is no question that we need better testing for Lyme disease,” she says. “The C6 EIA has some benefits but is clearly not sufficient.
- Nigrovic LE, Bennett JE, Balamuth F, et al. Diagnostic performance of C6 enzyme immunoassay for Lyme arthritis. Pediatrics. 2019 Dec 13. pii: e20190593. [Epub ahead of print]
- Oliveira CR, Shapiro ED. Lyme arthritis and clinical judgment. Pediatrics. 2019 Dec 13. pii: e20191998. [Epub ahead of print]