Description of biphasic patients
During the study period, 237 patients with available tryptase measurements and a suspected anaphylaxis event consulted at our allergy center (Figure 1); 13 (5.5%) had a biphasic reaction. Detailed characteristics of these patients are in Table 1.
Six of the 13 patients (46%) presented a severe secondary reaction (Ring and Messmer grade III-IV), whereas 7 patients (64%) had a mild or moderate reaction (Ring and Messmer grade I-II). The mean delay between the first and second reaction was 8 hr (range 1-48). As compared with the first reaction, the second was less severe for 5 (38.5%) patients, as severe for 7 (53.8%) patients and more severe for only one (7.7%) patient. Nine patients required a transfer to an intensive care unit for the biphasic reaction, and 2 were already hospitalized when the biphasic reaction occurred. The identified allergens were Hymenoptera venom for 6 patients, neuro-muscular blocking agents (NMBAs) for 4 patients, antibiotics for 2 patients, and seafood for one patient.