Six years of INSTAND e. V. sIgE proficiency testing

Abstract

BackgroundEven though allergies are an important health issue, wide manufacturer-dependent differences in the detected amounts of allergen-specific IgE (sIgE) have repeatedly been found. These discrepancies hinder diagnostics and research into clinically significant cutoff points for life-threatening symptoms.MethodsTo evaluate whether the reported differences have led to changes in diagnostic testing, we analyzed data from six years of round robin testing (RRT, also known as proficiency testing) at the Gesellschaft zur Förderung der Qualitätssicherung in medizinischen Laboratorien e.V. (Society for Promoting Quality Assurance in medical Laboratories) for the important allergen sources bee venom, wasp venom, and birch pollen. The results of the four main suppliers of in vitro diagnostic sIgE testing were compared in a pseudo-anonymized form using overlay images of box plot graphs for the semiquantitative data and allergen class results. Coefficients of variation (CV) were obtained to study the development of interlaboratory comparability.ResultsWe found that the large differences between the manufacturer collectives remained constant between January 2010 and April 2015 without any real improvement. The CVs were good for two of the four analyzed suppliers, one was marginal and one above the quality level of 20%.ConclusionThe numerous publications that have found discrepancies in the sIgE results of the different suppliers did not change the status quo within the last six years. Unfortunately, this is unlikely to change until there is a characterized standard material with known values of sIgE.

Allergen Immunotherapy in Children User’s Guide

“…Translating this problem into the daily clinical practice, divergent SPT wheal reactions for the same allergen species in the same patient elicited by different allergen extracts are not surprising . The variability of in vitro IgE test results to extracts of the same allergen source can in part similarly be attributed to the extract composition . Standardization of allergen extracts both for diagnosis and for therapy hence remains an issue in allergology.…”

Evaluation of INSTAND e.V.’s external quality assessment for C-reactive protein and procalcitonin

“…Even if these CV are lower than the ones, we observed previously for allergy diagnostics [25, 26], they could have a diagnostic impact: A decrease in CRP of at least 25% compared to the patient’s previous test result is considered a good indicator of sepsis resolution. With a variation potential of up to 30% for the immunological methods, the clinically relevant decline might be indicated by the uncertainty the tests alone.…”