METHODS: Patients' records referred for perioperative hypersensitivity reaction between 2001-2016 were revised. Anaphylaxis was defined according to WAO/AAAAI criteria and graded according to Brown’s classification. Peak tryptase was quantified within 6 hours from the event. Median time between index reaction and baseline tryptase measurement was 9 weeks (1-910). Patients underwent allergological work-up including skin tests, specific IgE and basophil activation test.
RESULTS: In 180/532 patients fulfilling the criteria of anaphylaxis acute and basal tryptase was available. 139/180 (77%) showed evidence of MCA. MCA was predominantly observed in grade III reactions (125/147 [85%]) versus grade II (8/20 [40%]) and grade I and (6/13 [46 %]) (p<0.05). IgE-mediated reactions were significantly more prevalent in patients with MCA than without MCA (111/139 [80%] vs 17/41 [42%]; p<0.05). The most frequent identified culprits in case of MCA were NMBA (rocuronium), antibiotics (cefazolin), latex and chlorhexidine.
CONCLUSIONS: According to the consensus formula MCA was demonstrable in 77% of cases in whom peak and baseline tryptase was available. MCA was significantly more associated with severe grade III reactions and IgE-mediated anaphylaxis. Absence of MCA does not exclude an IgE-mediate anaphylaxis. Therefore, confirmatory testing should not be restricted to patients with MCA.