Shelley Dua1, James Dowey2, Loraine Foley3, Sabita Islam3, Yvonne King3, Pamela Ewan3, Andrew T Clark3. 1. Department of Medicine, University of Cambridge, Cambridge, UK. Electronic address: shelley.dua@addenbrookes.nhs.uk. 2. Department of Economic History, London School of Economics and Political Science, London, UK. 3. Department of Allergy, Addenbrooke's Hospital, Cambridge, UK.
Abstract
BACKGROUND: Serum tryptase is useful in diagnosing drug and venom anaphylaxis. Its utility in food anaphylaxis is unknown. OBJECTIVE: The objective of this study was to determine whether tryptase rises in food allergic reactions, optimal sampling time points, and a diagnostic cutoff for confirming a clinical reaction. METHODS: Characterized peanut allergic patients were recruited and underwent up to 4 peanut challenges and 1 placebo challenge each. Tryptase was measured serially on challenge days both before (baseline) and during the challenge. The peak percentage tryptase rise (peak/baseline) was related to reaction severity. Receiver operating characteristic (ROC) curves were generated establishing an optimal diagnostic cutoff. RESULTS: Tryptase was analyzed in 160 reactive (9% anaphylaxis) and 45 nonreactive (placebo) challenges in 50 adults aged 18 to 39 years. Tryptase rose above the normal range (11.4 ng/mL) in 4 of 160 reactions. When compared with baseline levels, a rise was observed in 100 of 160 (62.5%) reactions and 0 of 45 placebo challenges. The median rise (95% confidence interval [CI]) for all reactions was 25% (13.3% to 33.3%) and 70.8% (33.3% to 300%) during anaphylaxis. Peak levels occurred at 2 hours and correlated with severity (P < .05). Moderate-to-severe respiratory symptoms, generalized erythema, dizziness, and hypotension were correlated with a higher peak/baseline tryptase (P < .05). ROC curve analysis demonstrated the optimal cutoff to identify a reaction as a 30% rise (sensitivity 0.53; specificity 0.85), area under the curve 0.72 (95% CI, 0.67-0.78). CONCLUSIONS: Serum tryptase measurement is valuable in food allergic reactions, and correlates with symptom severity. Comparing peak reaction levels at 2 hours with baseline is essential. A rise in tryptase of 30% is associated with food allergic reactions. Crown
BACKGROUND: Serum tryptase is useful in diagnosing drug and venom anaphylaxis. Its utility in food anaphylaxis is unknown. OBJECTIVE: The objective of this study was to determine whether tryptase rises in food allergic reactions, optimal sampling time points, and a diagnostic cutoff for confirming a clinical reaction. METHODS: Characterized peanutallergicpatients were recruited and underwent up to 4 peanut challenges and 1 placebo challenge each. Tryptase was measured serially on challenge days both before (baseline) and during the challenge. The peak percentage tryptase rise (peak/baseline) was related to reaction severity. Receiver operating characteristic (ROC) curves were generated establishing an optimal diagnostic cutoff. RESULTS: Tryptase was analyzed in 160 reactive (9% anaphylaxis) and 45 nonreactive (placebo) challenges in 50 adults aged 18 to 39 years. Tryptase rose above the normal range (11.4 ng/mL) in 4 of 160 reactions. When compared with baseline levels, a rise was observed in 100 of 160 (62.5%) reactions and 0 of 45 placebo challenges. The median rise (95% confidence interval [CI]) for all reactions was 25% (13.3% to 33.3%) and 70.8% (33.3% to 300%) during anaphylaxis. Peak levels occurred at 2 hours and correlated with severity (P < .05). Moderate-to-severe respiratory symptoms, generalized erythema, dizziness, and hypotension were correlated with a higher peak/baseline tryptase (P < .05). ROC curve analysis demonstrated the optimal cutoff to identify a reaction as a 30% rise (sensitivity 0.53; specificity 0.85), area under the curve 0.72 (95% CI, 0.67-0.78). CONCLUSIONS: Serum tryptase measurement is valuable in food allergic reactions, and correlates with symptom severity. Comparing peak reaction levels at 2 hours with baseline is essential. A rise in tryptase of 30% is associated with food allergic reactions. Crown
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