Abbie Francis1,2, Daniel M Fatovich1,2,3, Glenn Arendts1,2,3,4, Stephen Pj Macdonald1,2,3,5, Erika Bosio1,2, Yusuf Nagree1,4,6, Hugh Ma Mitenko1,7, Simon Ga Brown1,2,3,8,9. 1. Centre for Clinical Research in Emergency Medicine, Harry Perkins Institute of Medical Research, Perth, Western Australia, Australia. 2. School of Medicine, The University of Western Australia, Perth, Western Australia, Australia. 3. Emergency Department, Royal Perth Hospital, Perth, Western Australia, Australia. 4. Emergency Department, Fiona Stanley Hospital, Perth, Western Australia, Australia. 5. Emergency Department, Armadale Kelmscott Memorial Hospital, Perth, Western Australia, Australia. 6. Emergency Department, Fremantle Hospital and Health Service, Fremantle, Western Australia, Australia. 7. Emergency Department, South West Health Campus, Bunbury, Western Australia, Australia. 8. Emergency Department, Royal Hobart Hospital, Hobart, Tasmania, Australia. 9. School of Medicine, University of Tasmania, Hobart, Tasmania, Australia.
Abstract
OBJECTIVE: Clinical diagnosis of anaphylaxis is principally based on symptoms and signs. However, particularly for patients with atypical symptoms, laboratory confirmation of anaphylaxis would be useful. This study investigated the utility of mast cell tryptase, an available clinical biomarker, for differentiating anaphylaxis from other causes of critical illness, which can also involve mast cell activation. METHODS: Tryptase was measured (ImmunoCAP) in serum from patients with anaphylaxis and non-anaphylactic critical illness (controls) at ED arrival, and after 1-2, 3-4 and 12-24 h. Differences in both peak and delta (difference between highest and lowest) tryptase concentrations between groups were investigated using linear regression models, and diagnostic ability was analysed using Receiver Operating Characteristic curve analysis. RESULTS: Peak tryptase was fourfold (95% CI: 2.9, 5.5) higher in anaphylaxis patients (n = 67) than controls (n = 120) (P < 0.001). Delta-tryptase was 5.1-fold (95% CI: 2.9, 8.9) higher in anaphylaxis than controls (P < 0.001). Optimal test characteristics (sensitivity: 72% [95% CI: 59, 82] and specificity: 72% [95%CI: 63, 80]) were observed when peak tryptase concentrations were >11.4 ng/mL and/or delta-tryptase ≥2.0 ng/mL. For hypotensive patients, peak tryptase >11.4 ng/mL had improved test characteristics (sensitivity: 85% [95% CI: 65, 96] and specificity: 92% [95% CI: 85, 97]); the use of delta-tryptase reduced test specificity. CONCLUSION: While peak and delta tryptase concentrations were higher in anaphylaxis than other forms of critical illness, the test lacks sufficient sensitivity and specificity. Therefore, mast cell tryptase values alone cannot be used to establish the diagnosis of anaphylaxis in the ED. In particular, tryptase has limited utility for differentiating anaphylactic from non-anaphylactic shock.
OBJECTIVE: Clinical diagnosis of anaphylaxis is principally based on symptoms and signs. However, particularly for patients with atypical symptoms, laboratory confirmation of anaphylaxis would be useful. This study investigated the utility of mast cell tryptase, an available clinical biomarker, for differentiating anaphylaxis from other causes of critical illness, which can also involve mast cell activation. METHODS: Tryptase was measured (ImmunoCAP) in serum from patients with anaphylaxis and non-anaphylactic critical illness (controls) at ED arrival, and after 1-2, 3-4 and 12-24 h. Differences in both peak and delta (difference between highest and lowest) tryptase concentrations between groups were investigated using linear regression models, and diagnostic ability was analysed using Receiver Operating Characteristic curve analysis. RESULTS: Peak tryptase was fourfold (95% CI: 2.9, 5.5) higher in anaphylaxis patients (n = 67) than controls (n = 120) (P < 0.001). Delta-tryptase was 5.1-fold (95% CI: 2.9, 8.9) higher in anaphylaxis than controls (P < 0.001). Optimal test characteristics (sensitivity: 72% [95% CI: 59, 82] and specificity: 72% [95%CI: 63, 80]) were observed when peak tryptase concentrations were >11.4 ng/mL and/or delta-tryptase ≥2.0 ng/mL. For hypotensivepatients, peak tryptase >11.4 ng/mL had improved test characteristics (sensitivity: 85% [95% CI: 65, 96] and specificity: 92% [95% CI: 85, 97]); the use of delta-tryptase reduced test specificity. CONCLUSION: While peak and delta tryptase concentrations were higher in anaphylaxis than other forms of critical illness, the test lacks sufficient sensitivity and specificity. Therefore, mast cell tryptase values alone cannot be used to establish the diagnosis of anaphylaxis in the ED. In particular, tryptase has limited utility for differentiating anaphylactic from non-anaphylactic shock.
Authors: Andrew F Whyte; Jasmeet Soar; Amy Dodd; Anna Hughes; Nicholas Sargant; Paul J Turner Journal: Clin Med (Lond) Date: 2022-07 Impact factor: 5.410
Authors: Thomas Boehm; Birgit Reiter; Robin Ristl; Karin Petroczi; Wolfgang Sperr; Thomas Stimpfl; Peter Valent; Bernd Jilma Journal: Allergy Date: 2019-01-01 Impact factor: 13.146