About 1 in 8 anaphylaxis cases thought to be caused by medications

Medications were implicated in 12% of Victorian public and private emergency department presentations with anaphylaxis, according to research published today by the Medical Journal of Australia.

"From 1 November 2018, the Victorian Department of Health Department of Health and Human Services listed anaphylaxis as a notifiable condition," wrote the authors, led by Dr. George Drewett, an infectious diseases registrar at Austin Health.

That ruling allowed the incidence, causes, and characteristics of anaphylaxis to be analyzed for the first time.

Drewett and colleagues reviewed all cases of anaphylaxis reported to the Victorian Department of Health during 1 November 2018–31 December 2020.

"A total of 4,273 anaphylaxis episodes were reported (females: 2,292 cases, 54%); the overall anaphylaxis rate was 31.9 episodes per 100,000 person-years. The most frequently reported causes were foods (2,659 cases, 62%); drugs were implicated in 533 cases (12%), insect venoms in 342 (8%), and other causes in 144 (4%). No deaths were recorded," they reported.

"The median age in cases of food-related anaphylaxis was 17 years; and 45 years in cases of drug-related anaphylaxis.

"Hospitalization was required by 1,538 patients (36%) and intensive care by 111 (2.6%; 7% of people admitted to hospital).

"Antimicrobial drugs were implicated in 258 cases of drug-related anaphylaxis (48%) and non-steroidal anti-inflammatory drugs in 85 cases (16%). Penicillin-class agents were implicated in 143 cases of antimicrobial-related anaphylaxis (56%), cephalosporins in 80 cases (31%)."

Drewett and colleagues wrote that their findings were "largely consistent" with those of a retrospective multicentre cohort study in tertiary Australian hospitals during 2010–2015.

"Our study provides a unique analysis of drug- and antimicrobial-related anaphylaxis, for which prospective data are scarce; many studies have been based upon retrospective analyses of hospital stays," they concluded.

"Understanding the reasons for and the outcomes of drug-related anaphylaxis in Australia could improve decisions about prescribing and treatment."