Abbreviations: ASD, absolute standardized difference; H1 blocker, histamine-1 receptor blockers; H2 blocker, histamine-2 receptor blockers; SD, standardized difference; β2 agonist, beta 2-adrenergic receptor stimulants.

†: T78.0, Anaphylactic shock due to adverse food reaction

‡: T78.2, Anaphylactic shock, unspecified

§: T88.6, Anaphylactic shock due to adverse effect of correct drug or medicament properly administered

Table 2 . Proportions of biphasic reactions and 7-days all-cause mortality in unmatched and propensity score-matched groups