Objective:

To evaluate the agreement between crude extract and corresponding component allergen results using a MAST panel in a large clinical laboratory cohort.

Approach:

• Study Design: Retrospective analysis of deduplicated MAST results from a high-volume referral laboratory over a two-month period.
• Data Analysis: Positivity rates assessed using a cutoff of class 2 or higher (≥0.70 IU/mL); concordance defined as both crude extract and at least one component allergen being positive, or both being negative.
• Statistical Evaluation: Agreement evaluated using percent agreement and Cohen’s kappa coefficient.

Key Findings:

• A total of 19,949 patients were included.
• The highest positivity rates were observed for Dermatophagoides farinae (31.8%), D. pteronyssinus (29.9%), rDer f 2 (24.2%), and cat epithelium (12.2%).
• Overall percent agreement exceeded 90% for most allergen pairs, primarily driven by high negative agreement.
• Cohen’s kappa revealed substantial agreement (κ ≥ 0.6) for ten allergens including D. farinae, cat dander, and birch pollen, whereas eight allergens including D. pteronyssinus and milk showed poor agreement (κ < 0.1) due to low component allergen positivity despite positive crude extract results.

Interpretation:

Limitations:

• Study limited to a specific two-month period and a single high-volume referral laboratory.
• Findings may not be generalizable to other settings or populations.

Conclusion: