No More Western Blots for Lyme Diagnosis?

April 30, 2013

http://www.medscape.com/infectiousdiseases

NEW YORK (Reuters Health) Apr 30 – Regardless of travel history, Lyme disease can be diagnosed with a two-tiered algorithm that employs a standard Lyme disease ELISA, followed by a newer-generation C6 peptide ELISA, a new study suggests.

With the newer approach, “there is no requirement for cumbersome immunoblots, including IgM Western blotting, a test that has not fared well in the real world,” said Dr. Robert Schoen from Yale University School of Medicine in New Haven, Connecticut in an editorial published with the study in Clinical Infectious Diseases. “Both steps in this algorithm, the initial standard ELISA and the C6 peptide ELISA, are already

commercially available. It may be time to incorporate this newer two-tiered algorithm in clinical practice.”

“This newer approach has been previously demonstrated to be more sensitive in early Lyme disease than conventional, CDC recommended testing and equally specific for all stages of the illness,” he added.

The new study focused in particular on the problem presented by patients in the U.S. who might have acquired Lyme borreliosis (LB) in Europe.

The data showed that standard two-tiered testing (ELISA followed by immunoblot) using assays developed for use in the US was “inferior” to European assays for evaluating LB acquired in Europe, as Dr. Schoen pointed out in his editorial.

“This result is not surprising,” he wrote, “since Lyme disease in North America is caused by a single borrelial species, B. burgdorferi sensu stricto (s.s.). European tests would be expected to have better predictive value than US tests for European acquired infection.”

The researchers, led by Dr. John Branda from Massachusetts General Hospital in Boston, analyzed the sensitivity of each assay using 64 serum samples from infected patients at a single European site (Ljubljana, Slovenia) with early or late disease manifestations. Specificity was measured using 100 sera from healthy subjects from a non-endemic area (New Zealand).

For detection of European-acquired infection, conventional two-tiered testing (ELISA followed by immunoblot) using US assays had an overall sensitivity of 52% and specificity of 100% compared with 81% (p=0.0007) and 99% (p=1.0) using analogous European tests, the investigators reported online April 16th.

But the sensitivity of a US C6 ELISA used as a standalone test was 88% overall – statistically comparable to that of conventional two-tiered testing using European tests (p=0.47) and was 100% specific.

Similarly, an alternative two-tiered algorithm using a standard ELISA followed by a C6 ELISA was comparably sensitive (84% overall) compared with conventional two-tiered testing using European assays (p=0.82) and specificity remained 100%.

So what’s the “take home” message? Dr. Schoen says the C6 ELISA, used as a standalone test or as the second test in a two-tiered algorithm following a standard US ELISA “can be recommended for the diagnosis of Lyme disease acquired in North America and Europe and probably elsewhere. But the C6 ELISA as part of the two-tiered algorithm is a better test than the standalone test, because it is more specific.”

Dr. Branda did not respond to request for comment by press time.

The study had no commercial funding. Three of the authors have submitted a patent application for a point-of-care serodiagnostic test based on the algorithm described in the report and have received compensation from Alere Inc for collection and characterization of serum samples from patients with Lyme disease. Dr. Schoen has no conflicts of interest.

SOURCE: http://bit.ly/15WMFgA and http://bit.ly/15WMFgA

Clin Infec Dis 2013.

Carl Tuttle