Refining the diagnosis of house dust mite-induced allergic rhinitis: optimizing SPT and sIgE cutoff values as predictors of clinically relevant allergy

Skin prick testing (SPT) and serum-specific IgE (sIgE) measure sensitization rather than clinical allergic rhinitis (AR), making nasal provocation testing (NPT) the reference standard for confirming clinically relevant allergy. A cross-sectional study was conducted on 122 adult AR patients (18–60 years). Participants underwent SPT, sIgE measurement, and NPT for Der p and Der f. Correlations between SPT, sIgE, and NPT results were analyzed, and receiver operating characteristic (ROC) analysis was performed to determine optimal diagnostic cutoffs. Among participants, 106 (86.9%) were SPT-positive for Der p and 80 (65.6%) for Der f. Using the conventional screening threshold (sIgE ≥ 0.35 IU/mL), 86 (70.5%) were positive for Der p and 60 (49.2%) for Der f. NPT positivity was observed in 88 (72.1%) patients for Der p and in 68 (55.7%) patients for Der f. ROC analysis identified higher cutoffs associated with improved specificity: ≥4.2 mm mean wheal diameter (MWD) for SPT and ≥ 1.10 IU/mL for sIgE in Der p, and ≥ 3.75 mm MWD and ≥ 0.50 IU/mL for Der f. While the conventional sIgE threshold (≥ 0.35 IU/mL) remained a strong independent predictor of NPT positivity, the ROC-derived cutoffs demonstrated enhanced diagnostic precision. Our results suggest that although conventional thresholds remain appropriate for initial screening, the ROC-optimized values identified in this study provide greater diagnostic precision and may aid clinical decision-making when NPT is unavailable.