Clin Exp Allergy. 1998 Dec; 28(12): 1526-9.
Unreliability of IgE/IgG4 antibody testing as a diagnostic tool in food intolerance.
Royal London Homoeopathic Hospital NHS Trust and Research Council for Complementary Medicine, UK.
BACKGROUND: Some clinicians link chronic disease in certain patients to 'food intolerance'. This is currently diagnosed by exclusion dieting, a time-consuming and tedious technique. It has been claimed that IgE/IgG4 antibody testing is a rapid and valid method of determining food intolerance. OBJECTIVE: To determine the test/retest reliability of IgE/IgG4 antibody testing as a diagnostic tool. METHODS: Blinded testing of duplicate blood samples from nine patients with suspected food intolerance was undertaken by tertiary referral centre using the services of a commercial laboratory. The proportions of consistent and inconsistent results for tests of 95 different foods were analysed. RESULTS: Test/retest reliability was low. Even though the study method systematically overestimated kappa, this value never exceeded 0.51, regardless of the statistical model used. All but one patient had a greater number of inconsistent results than had been prespecified as an unacceptable level of disagreement. In one case, 50 out of 95 test results were inconsistent on retest. CONCLUSIONS: We found no evidence that IgE/IgG4 antibody testing as performed by this laboratory is a reliable diagnostic tool.