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The Natural History of Peanut and Egg Allergy and Predictors of Persistence: The Healthnuts Longitudinal Study, 6-Year-Old Follow-up.

      Rationale

      There is little prospectively collected data on the natural history of egg and peanut allergy. We examined whether skin prick test (SPT) thresholds or clinical factors present at diagnosis could predict the persistence or resolution of food allergy in early childhood.

      Methods

      One-year-old infants with challenge-confirmed peanut (n = 156) and egg (n = 468) allergy from the population-based, HealthNuts Study (n = 5276) underwent follow-up at age 6 year including SPT and oral food challenge (OFC). Children with SPT ≥ 8 mm and positive OFC at age 4 years were considered persistent allergic at age 6 without challenge.

      Results

      Peanut allergy resolved in 31% (95% CI 24-40%; n = 41/131) and egg allergy resolved in 89% (95% CI 85-92%; n = 284/320) at age 6. At age 6, SPT ≥5mm (95% CI 1-7mm) and ≥6mm (95% CI 5-7mm) had 95% positive predictive value to persistent peanut and egg allergy, respectively, while SPT ≤2mm had 95% or 98% negative predictive value to resolved peanut and egg allergy, respectively. SPT measured at age 1 was a poor predictor of persistent food allergy at age 6 (peanut: AUC 0.65 95%CI 0.55-0.75, egg: AUC 0.69 95%CI 0.59-0.78). Eczema at age 1 was associated with persistent food allergy (peanut: aOR 2.74 (95%CI 1.13-6.62), egg: aOR 3.53 (95%CI 1.31-9.47)); tree nut sensitisation at age 1 year was associated with persistent peanut allergy (aOR 2.63 (95%CI 0.99-6.96)).

      Conclusions

      We report SPT thresholds at age 6 with 95% PPV to persistent food allergy. SPT at diagnosis was a poorly predictor of persistent food allergy although coexisting allergies at diagnosis were associated with persistent food allergy.