D2.14 - Component ratio analysis supports a targeted diagnostic approach in house dust mite allergy

Dermatophagoides pteronyssinus is among the allergenic sources with the greatest number of available molecular components for diagnostic testing. However, it remains unclear whether this molecular complexity -particularly when multiple components are tested simultaneously- leads to improved diagnostic accuracy or better treatment outcomes. This raises the question of whether general extensive component testing in house dust mite (HDM) allergy is truly beneficial, or whether alternative strategies, such as component ratio analysis and inhibition assays, may provide greater clinical value.The aim of this study was to evaluate the added diagnostic value of component ratio analysis in the assessment of HDM allergy.

This retrospective, single-center, non-interventional study included 7,402 patients tested for Dermatophagoides pteronyssinus whole extract (we) specific IgE (sIgE). In addition, sIgE to Der p 1, Der p 2, Der p 10, and Der p 23 was measured according to clinicians’ judgment in routine clinical practice. All analyses were performed using the ImmunoCAP™ sIgE singleplex method (Thermo Fisher Scientific, Uppsala, Sweden) in accordance with the manufacturer’s instructions. Results were considered positive at sIgE levels ≥0.35 kUA/L. Ratio 2 (component sIgE / whole-extract sIgE) was calculated when data were available.

Der p 1 and Der p 2 testing was requested in approximately 90% of patients with positive whole-extract sIgE. Der p 23 and Der p 10 were requested in 10% and 3% of cases, respectively. Positivity rates were approximately 90% for Der p 1, Der p 2, and Der p 23, whereas Der p 10 showed a lower positivity rate of 70%.Component-to-extract ratios were calculated in 801 patients. The combined Ratio 2 for Der p 1 and Der p 2 exceeded 80% in 345 patients. Only 8% of patients showed a higher relative contribution of Der p 23 (Ratio 2 Der p 23 / Ratio 2 [Der p 1 + Der p 2] ≥0.5). Predominant sensitization to Der p 10 was observed in only two patients; in most cases, this component was absent or clinically irrelevant based on ratio analysis.

Component ratio analysis is a valuable tool for assessing the relative contribution of individual allergens. In HDM allergy, the clear predominance of Der p 1 and Der p 2 indicates that expanded component testing is generally unnecessary as a first-line  strategy. Additional testing should be reserved for selected cases in which ratio analysis suggests a meaningful contribution from other components. This stepwise approach supports more targeted diagnostics while minimizing unnecessary testing.