Serum mast cell tryptase measurements: Sensitivity and specificity for a diagnosis of anaphylaxis in emergency department patients with shock or hypoxaemia

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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.

Original languageEnglish
JournalEmergency Medicine Australasia
DOIs
Publication statusE-pub ahead of print - 2 Nov 2017

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Tryptases
Anaphylaxis
Hospital Emergency Service
Shock
Sensitivity and Specificity
Serum
Critical Illness
Linear Models
Hypoxia
Mast Cells
ROC Curve
Signs and Symptoms
Biomarkers
Regression Analysis

Cite this

@article{a4a7e860a44b4950babe11e98f179b0a,
title = "Serum mast cell tryptase measurements: Sensitivity and specificity for a diagnosis of anaphylaxis in emergency department patients with shock or hypoxaemia",
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.",
keywords = "Journal Article",
author = "Abbie Francis and Fatovich, {Daniel M} and Glenn Arendts and Macdonald, {Stephen P.J.} and Erika Bosio and Yusuf Nagree and Mitenko, {Hugh M.A.} and Brown, {Simon G.A.}",
note = "{\circledC} 2017 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine.",
year = "2017",
month = "11",
day = "2",
doi = "10.1111/1742-6723.12875",
language = "English",
journal = "Emergency Medicine",
issn = "1742-6723",
publisher = "John Wiley & Sons",

}

TY - JOUR

T1 - Serum mast cell tryptase measurements

T2 - Sensitivity and specificity for a diagnosis of anaphylaxis in emergency department patients with shock or hypoxaemia

AU - Francis, Abbie

AU - Fatovich, Daniel M

AU - Arendts, Glenn

AU - Macdonald, Stephen P.J.

AU - Bosio, Erika

AU - Nagree, Yusuf

AU - Mitenko, Hugh M.A.

AU - Brown, Simon G.A.

N1 - © 2017 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine.

PY - 2017/11/2

Y1 - 2017/11/2

N2 - 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.

AB - 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.

KW - Journal Article

U2 - 10.1111/1742-6723.12875

DO - 10.1111/1742-6723.12875

M3 - Article

JO - Emergency Medicine

JF - Emergency Medicine

SN - 1742-6723

ER -