Validation of International consensus equation for acute serum total tryptase in mast cell activation: A perioperative perspective

Abstract

Introduction

There is no standardised method for assessing serum total mast cell tryptase (MCT) in anaphylaxis. The consensus equation (peak MCT should be>1.2x baseline tryptase+2mg/L) has been proposed to interpret acute MCT in mast cell activation syndrome (MCAS).

Aim

To validate consensus equation in a setting of perioperative anaphylaxis.

Methods

Analyses of suspected perioperative anaphylaxis during general anaesthesia (GA). Anaphylaxis was defined as per World Allergy Organisation (WAO) criteria. Timed serial MCT measurements were mapped against the consensus equation and receiver operating characteristic (ROC) curves produced.

Results

82 patients (60 females, mean age 56.5 years ± SD17.2) underwent investigation. 60 (73%) patients fulfilled WAO criteria for anaphylaxis and 22 patients did not (controls). Aetiology: 59% IgE-mediated anaphylaxis, 2% non-IgE mediated anaphylaxis, 12% anaphylaxis of unknown cause, and 27% deemed non-anaphylaxis. IgE-mediated anaphylaxis included - NMBA (35%), antibiotics (46%), chlorhexidine (8%), patent blue dye (8%) and others (8%). An acute MCT with a comparable baseline was available in 71/82 (87%) patients (60-anaphylaxis and 11-controls).The median (IQR) time from reaction to peak MCT was 1.34 (0.82-2.51) hours. Analyses confirmed that a rise in acute MCT greater than that defined by the equation had a sensitivity, specificity, positive predictive value (PPV) and negative (N) PV of 78%, 91%, 98%, and 44% respectively. The magnitude of increase in acute MCT above the threshold predicted by consensus equation was higher in the anaphylaxis group compared to controls (P=0.0001).

Conclusion

This equation has a high specificity, PPV with a moderate NPV and sensitivity in perioperative anaphylaxis.

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