Diagnostic performance of serial serum total tryptase measurement to differentiate positive from negative allergy testing among patients with suspected perioperative hypersensitivity.

Background: Serum total tryptase has been shown to increase during acute allergic reactions (acute tryptase, T ); however, few studies have investigated the values of T or a combination of T and baseline tryptase (T ) to discriminate positive from negative testing in perioperative hypersensitivity reaction (POH) allergy work-up. The aim of this study was to determine the diagnostic performance of T in order to differentiate positive from negative allergy testing suspected POH and analyse the diagnostic performance of serial tryptase levels using several formulas.

Methods: All patients from the University hospital of Montpellier and Strasbourg, France, who presented with suspected POH and underwent complete drug allergy work-up between March 2011 and December 2019 with available T and T were included. Four formulas, including a change in T  > 11 (F1), or >2 + 1.2 × T (F2), or >3 + T (F3), or >120%T (F4), were applied.

Results: One hundred and sixty-two patients were included, and 131 of them (80.8%) had Grade III or IV reactions. Ninety patients had positive allergy testing. The optimal cut-off value of T to distinguish positive from negative allergy testing patients was 9.8 μg/L with an AUC of 0.817 (95% CI: 0.752-0.882, p < .001). The 93% PPV threshold for T was 33 μg/L (95.8% specificity). Paired tryptase levels according to formulas F2 and F3 yielded the highest Youden index (0.54 and 0.53, respectively).

Conclusion: The optimal cut-off point for T for distinguishing positive from negative allergy testing suspected POH was 9.8 μg/L. T value of 33 μg/L was required to achieve >90% PPV.