CONTINUOUS LIKELIHOOD RATIOS TO PREDICT THE PROBABILITY OF A PEANUT REACTION

Abstract

Introduction Peanut-specific IgE (PsIgE) is used to predict the probability of a reaction using likelihood ratios (LR) which convert pretest to posttest probabilities. While dichotomous (positive or negative) LRs are defined using a cutoff of 0.35, it is better to use a continuous LR which corresponds to each value of PsIgE. This is particularly important when there is only a PsIgE and no history of prior ingestion to rely on. Methods PsIgEs were measured and oral peanut challenges performed on 58 children ages 9 months to 18 years. An ROC curve was determined using SPSS. The slope of the ROC curve, which is the likelihood ratio for each value of PsIgE, was determined by differentiated the ROC curve and used to convert sIgEs to likelood ratios. Results PsIgE ranged from 0 to 23. There were 33 negative and 25 positive oral challenges. The area under the ROC curve was 0.71 (p Conclusions Continuous LRs can provide a more accurate assessment of the probability of a peanut reaction for a given sIgE when the history of peanut ingestion is not known. Additional data points will refine these estimates.