Increasing Age Linked to More Severe Anaphylaxis, Medications Frequent Trigger for Older Adults

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This new research examined trends among adults with severe and recurrent anaphylaxis, and identified several major risk factors.

A recent analysis identified several trends among adults with anaphylaxis, including the following: increasing age is linked to more severe presentations, medications are more frequent trigger in older adults, and food-related anaphylaxis is both a risk factor for recurrent cases and the most common trigger.1

These findings and others resulted from a study which set out to assess the risk factors in adult patients with severe and recurrent anaphylaxis presentations. The study also sought to examine patient management strategies related to the cascade of care recommendations.

The research was authored by Jacqueline Loprete, MBBS, from the Immunology and HIV Unit of St. Vincent’s Hospital in Sydney, Australia.

“By identifying risk factors, including comorbidities and potential gaps in education and ongoing management after initial anaphylaxis, it may be possible to reduce anaphylaxis incidence or severity,” Loprete and colleagues wrote.

Background and Findings

The investigators conducted the study at St. Vincent’s Hospital in Sydney, Australia, a tertiary-care facility with 402 beds that is known to treat patients aged 16 years and older. The hospital's ED receives over 49,000 anaphylactic presentations annually.

The research team’s work involved auditing the records of individuals who visited the hospital's ED with anaphylactic presentations in the time frame between January of 2009, and December of 2018. Data from electronic and paper records were reviewed by the team, covering various aspects including medical history, demographics, presenting event information, co-factors involved, treatment given, and discharge disposition.

Severe anaphylaxis, as per the Brown criteria, was defined by specific symptoms.2 The investigators also assessed whether the recommended cascade of care was carried out for each individual, including steps like monitoring, adrenaline administration, providing an adrenaline autoinjector at discharge, and advising follow-up with a specialist in allergies.

The data collected by the research team were entered into an electronic data collection form and analyzed using Stata, and their analysis involved examining associations through the use of odds ratios (ORs) and t-tests to compare distinctions between various groups.

Overall, the investigators’ research involved 616 patients (median age: 31 years, 56.3% female) recorded 689 occurrences in total, with 8.3% of patients experiencing anaphylaxis on at least 2 occasions. In 68.7% of episodes, the triggering agents were identified by the research team.

The primary triggers were found to be food-related (73.4% of cases with known triggers), with peanuts and seafood being the most common culprits. Among these food-related episodes, 76.4% were associated with food consumed outside one’s home or consuming food prepared by others.

Additionally, the investigators reported that drugs and medications were shown to be the second most prevalent triggers (22.4% of episodes), and that non-steroidal anti-inflammatories being the major contributor.

Individuals over the age of 65 were found to have identifiable triggers for anaphylaxis more often than younger individuals, with drugs/medications identified by the investigators as the predominant trigger in this age group (75% vs. 20.1% in those under 65). Being over 65 and having a history of asthma were noted as independent risk factors for severe anaphylaxis.

The investigators also noted that a history of food allergy and food as the trigger were found to have been linked with recurrent anaphylaxis presentations in these patients. Only 19% of those included followed the recommended cascade of care, with deficiencies observed by the team in post-adrenaline monitoring and referrals to allergy specialists.

The study’s investigators also reported an increase in anaphylaxis presentations over time but no major differences in triggers or severity.

“More work is required to further establish possibly modifiable risk factors for anaphylaxis in adults with allergies and to work with healthcare professionals to ensure that education and appropriate resources are delivered and expected standards followed, to address these gaps in care,” they wrote.


  1. Loprete J, Montemayor J, Bramah V, et al. Predictors of severe and recurrent adult anaphylaxis, and gaps in the cascade of care: a retrospective, single-centre study 2009-2018 [published online ahead of print, 2023 Jul 18]. Intern Med J. 2023;10.1111/imj.16177. doi:10.1111/imj.16177.
  2. Harris PA, Taylor R, Thielke R, Payne J, Gonzalez N, Conde JG. Research electronic data capture (REDCap) – a metadata-driven methodology and workflow process for providing translational research informatics support. J Biomed Inform 2009; 42: 377–81.