Reproducibility of serum testing for environmental allergen-specific IgE in dogs in Europe

Serum testing for allergen-specific immunoglobulin (Ig)E is commonly employed to identify allergens used for allergen-specific immunotherapy in dogs, yet the reliability of results has been a matter of debate.

The aim of this study was to evaluate the reproducibility of serum tests for environmental allergen-specific IgE in three European laboratories.

Serum was obtained from 33 client-owned dogs diagnosed with atopic dermatitis, divided into three aliquots and sent to the laboratories under different names. Two aliquots were sent simultaneously to one of the laboratories on the first day; the third sample was then sent to the same laboratory on the subsequent day. The laboratory for each patient was chosen according to a predetermined randomization list. The agreement between different samples from the same dog for each of the laboratories was calculated with a Cohen's Kappa test. Spearman's rank coefficients (r_sp ) as well as the coefficients of variation (CV) additionally were calculated.

The intra- and interassay agreements for laboratories A, B and C were 0.79 and 0.75, 0.92 and 0.90, and 0.90 and 0.85, respectively. The CVs were 18.92% and 22.95%, 14.43% and 18.79%, and 15.38% and 18.75% (respectively) and the r_sp 0.73 and 0.68, 0.95 and 0.92, and 0.82 and 0.74 (respectively).

The differences in reproducibility between laboratories complicate test interpretation and underline the importance of interpreting results of serum testing for allergen-specific IgE in the context of the patient's clinical history.