Sensitivity and specificity of a commercial ELISA test for anti-MAG antibodies in patients with neuropathy.

For the diagnosis of anti-MAG polyneuropathy the commercial ELISA manufacturer currently recommends a cut-off of 1000 Bühlmann Titer Units (BTU). We analyzed sera from 80 anti-MAG neuropathy patients and 383 controls (with other neuropathies or healthy controls) to assess the ELISA sensitivity and specificity at different thresholds. A better combination of sensitivity/specificity was found at a threshold >1500 BTU than at >1000 BTU. The best value of specificity was obtained at threshold >7000 BTU. There was a diagnostic grey area between 1500 and 7000 BTU in which the clinical phenotypes as well as electrophysiological studies need to be carefully assessed particularly to differentiate CIDP and anti-MAG neuropathy.
Competing Interests: Declaration of Competing Interest E.N.O. reported personal fees for Advisory or Scientific Board from Kedrion, Italy, Baxter, Italy, Novartis, Switzerland, CSL-Behring, Italy, LFB, France, Astellas, the Netherlands, outside the submitted work and travel grants to attend Scientific Meeting from Baxter, Grifols, Kedrion, and Novartis, Italy. P.E.D. reported travel grants to attend scientific meetings from CSL Behring and Kedrion. G.L. reported travel grants to attend scientific meetings from CSL Behring and Kedrion. D.C. reported honoraria for lecturing from Shire, CSL Behring, and Kedrion and travel grants to attend scientific meeting from Shire, Kedrion, and CSL Behring. G.C. reported travel grants to attend scientific meetings from CSL Behring and Kedrion. F.M. reported personal fees for scientific events from CSL Behring and has received travel grants to attend scientific meetings from CSL Behring and Kedrion. G.C. reported honoraria for lecturing and travel grants to attend scientific meetings from Kedrion. M.F. has served on scientific advisory boards for CSL Behring and Sarepta Therapeutics and has received travel grants from Sanofi Genzyme, Kedrion, Baxter and CSL Behring to attend scientific meeting. G.A.M. reported consulence fees and travel fundings from CSL Behring, Kedrion, Shire and Grifols. G.A. reported honoraria for lecturing from Kedrion and Sanofi-genzyme, travel grants from Kedrion, Sanofi-Genzyme and LJ Pharma. The other authors declare no conflict of interest.
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