Table II.
Optimal cutoffs to classify subjects at high-risk for developing severe allergic reactions and reacting to a low dose (≤0.1 gs) of peanut protein during oral peanut challenge
| Parameters | Severe versus nonsevere allergic reactions |
Threshold ≤0.1 g vs >0.1 g of peanut protein |
||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Cutoff | Sensitivity | Specificity | PPV | NPV | Cutoff | Sensitivity | Specificity | PPV | NPV | |
| BAT (% of CD63+ basophils) | 48 | 100 (100-100) | 97 (95-98) | 41 (32-60) | 100 (100-100) | 1.7 | 95 (89-100) | 91 (86-96) | 43 (35-62) | 100 (99-100) |
| Ara h 2–specific IgE (kU/L) | 1.4 | 100 (100-100) | 93 (91-98) | 22 (18-48) | 100 (100-100) | 0.1 | 97 (90-100) | 89 (87-95) | 38 (34-57) | 100 (99-100) |
| Peanut-specific IgE (kU/L) | 5 | 100 (100-100) | 90 (87-98) | 18 (15-48) | 100 (100-100) | 0.4 | 95 (88 -100) | 79 (76-86) | 25 (23-34) | 100 (99-100) |
| Peanut-specific IgG4 (μg/L) | 175 | 75 (17-100) | 46 (30-99) | 3 (2-29) | 99 (98-100) | 75 | 82 (67-89) | 34 (32-45) | 8 (8-10) | 96 (94-98) |
| IgG4/IgE ratio | 1.6 | 100 (92-100) | 88 (86-98) | 16 (14-60) | 100 (100-100) | 2.1 | 91 (86-100) | 87 (78-92) | 35 (25-46) | 99 (99-100) |
| Peanut SPT (mm) | 8 | 100 (100-100) | 92 (89-94) | 21 (17-27) | 100 (100-100) | 6 | 98 (97-100) | 95 (91-96) | 59 (45-66) | 100 (100-100) |
Severity was assessed according to the Common Terminology Criteria for Adverse Events scale.18 Optimal cutoffs were determined on the basis of the Youden index, which is the distance between the point of inflection of the receiver operator characteristic curve and the reference line (see the Methods section in this article’s Online Repository at www.jacionline.org). Sensitivity, specificity, PPV, and NPV with 95% CIs are indicated for each cutoff.
NPV, Negative predictive value; PPV, positive predictive value.