Drug allergy is keeping our allergy services increasingly busy, but Dr Michaela Lucas believes general practice could save the day. 

The famously tragic case of David Vetter, the Texan child whose Severe Combined Immunodeficiency (SCID) resulted him living out his 12 short years of life inside a sterile bubble, made global headlines in the 1970s and 80s.

Despite his condition being the awful luck of genes and exceptionally rare, David Vetter’s SCID and his doctors’ novel treatment approach may have done much to fuel parents’ angst that the modern world was harming their children.

Dr Michaela Lucas, clinical immunologist and allergist

Dr Michaela Lucas, clinical immunologist and allergist

So have food, drugs and air quality changed so drastically that we are becoming ultra-sensitive to allergens? Or is it that human biology has changed? Or has it simply always been so and we are only now discovering the science to name it?

Clinical immunologist and allergist Dr Michaela Lucas, who is based at Sir Charles Gairdner and the Perth Children’s Hospital working on drug allergy, believes it is a combination of all those things.

“There has been a true increase in allergies as a result of our modern lifestyle – allergies across the board, from food to medication,” she told Medical Forum. “It was led by the increase in diagnosis of (allergy-related) asthma which has since plateaued but there remains a level of concern among consumers and some within the health profession.”

“Doctors are concerned about protecting their patients from harm, including medication intolerance, which is not the same as immune-mediated drug allergy. In particular, doctors and patients may overestimate the likelihood of a true allergy to an antibiotic, commonly penicillin, leading to an avoidance of that drug needlessly. This avoidance is leading to the increased use of broad spectrum antibiotics which has been linked to the emergence of antimicrobial resistance. However, lack of clinical testing and failings in current documentation practices may not protect patients with true allergy nor those who mistakenly believe they are ‘allergic’.

“There is a lack of consistent education in the antibiotic allergy field, and no clinical pathways to guide practitioners if someone with a self-reported penicillin allergy walks through their door.”

Michaela, along with colleagues Drs Richard Loh (Perth Children’s Hospital) and William Smith (Royal Adelaide Hospital), published an article in the February issue of Medical Journal of Australia highlighting the importance of national registries for people with verified drug allergies to increase patient safety, particularly in emergency situations.

They wrote:

“In Australia, drug allergy is the most common cause of fatal anaphylaxis. Drugs implicated in anaphylaxis deaths are antibiotics, anaesthetic agents, non-steroidal anti-inflammatories and radiocontrast media. Anaphylaxis and other serious drug allergy reactions are largely unpredictable; however, the risk is clearly elevated in patients who have had a previous reaction, offering an opportunity for prevention. In limited situations, genetic testing for risk of severe cutaneous drug reactions (e.g., abacavir, risk allele HLA-B*57:01) is also predictive.”

“A review of coronial findings in four drug allergy-related deaths between 2011 and 2013, conducted by the Australasian Society of Clinical Immunology and Allergy Drug Allergy Working Party, identified deficiencies in the knowledge and skills of health care professionals, including:

  • a lack of knowledge in recognising and appropriately managing severe allergic drug reactions;
  • unclear documentation of drug allergies;
  • a lack of knowledge with regards to generic versus trade names of drugs, and the potential cross-reactivity of drugs;
  • poor communication of known allergies (e.g. ignoring medical alert jewellery); and
  • misuse of terminology (e.g., “sulpha” instead of a specific drug name such as sulfamethoxazole).

“Therefore, improved education, communication and documentation are essential to prevent further fatal outcomes.”

Michaela says that while these deficiencies make it more difficult to get a true picture of the extent of drug allergy, there is no doubt that there is a true increase in incidence of allergic diseases.

While she said the allergy community in WA was small, it was growing with allergy services being established at PCH, SCGH and Fiona Stanley Hospital.

“We started from humble beginnings but now the clinics are busy and drug allergy comprises about a third of all the work we do,” she said. “At SCGH we have implemented a drug allergy training module for registrars and other colleagues. Going by the number of emails I get from other public and private hospitals, there is a growing need for dedicated drug allergy services.”

“Of course these services go hand in hand with antimicrobial stewardship practices because much of the drug allergy assessment concerns putative penicillin allergy which is commonly reported by patients. The US is leading the way here, tackling the problem of incorrect antibiotic allergy labels, but in Australia we have taken a similar approach and have proposed an evidence-based risk assessment strategy to determine how and when to test for antibiotic allergy. This approach will be published shortly in the Journal of Allergy and Clinical Immunology in Practice.

“I personally feel that other than having more time to take a detailed history, there is not a lot of difference between what a specialist can offer and what a GP can provide.” “In our current paper, we propose an algorithm to determine who would benefit from skin testing and who could be treated directly, in a way similar to a risk assessment for any vaccination or iron infusion. GPs treat some severe reactions to vaccination, so assessing drug allergy in many cases wouldn’t be much different.”

 “The paper provides good evidence that with models and standards of care, GPs can take on these cases. However, we need to access sustainable funding from within the MBS, because GPs are not reimbursed for this kind of care.” “It’s one thing to empower GPs to take on this work and another to make it viable, and it can only be viable if it is funded.”

In the MJA article, the authors recommended that among the priority areas for GPs to address was an improvement in the quality of the drug allergy history, which should be complete with contemporaneous details of the reaction, culprit drug, reaction type and severity.  Michaela suggested that standardised formats for electronic health records would facilitate the accurate documentation of adverse drug reactions including allergy.

A more extensive understanding of the mechanisms of drug allergy and the likelihood of cross reactivity was also highlighted together with the confidence to understand the risk of reaction.

With so many antibiotic reactions being self-reported, the paper asserts the importance of verifying or dismissing drug allergy labels. “Communicating drug allergy information and drug avoidance advice, such as degree of contraindication, is of central importance, particularly in emergency and perioperative situations as well as in any clinical context, including community practice, hospitals and pharmacies. This could be achieved through well designed, linked and reconciled local or national EHRs, national registries of verified drug reactions, and validated medical alerting devices,” they write.

Time is of the essence. With antimicrobial resistant bacteria becoming a growing spectre, a lot of work on drug allergy is being done in this context. Michaela points to a paper by a US colleague, Kimberley Blumenthal, who suggested that a patient with a penicillin allergy admitted to hospital stands a greater chance of developing an infection with multi-resistant bacteria.

To have these patients identified and tested in primary care will help.

“We might be OK now but if we don’t make changes to our system now and preserve our antibiotics we will definitely run into trouble in 50 years’ time. And patients who have complex drug allergies who have to avoid antibiotics are often those most vulnerable,” she said.

ED The 30th annual conference of the Australasian Society of Clinical Immunology and Allergy will be held in Perth at the PCEC starting on September 3. Dr Michaela Lucas is the conference chair.

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