Improving drug allergy management in Australia: education, communication and accurate information

Drug allergy education and effective communication of accurate information can optimise drug allergy management and patient safety

A drug allergy label is often applied to a patient after an adverse drug reaction (ADR), usually resulting in subsequent avoidance of the drug and related drugs. Recent attention has focused on antibiotic allergy labels and the benefits of delabelling.1 But drug allergy labels, which occur in up to 35% of patient electronic health records (EHRs), encompass all types of medications, with antibiotics, opiates and non-steroidal anti-inflammatory drugs being among the most common (Box 1).2 Accurate and effective communication of drug allergy is crucial for safe prescribing, including sufficient information to enable assessment of the risk of re-exposure compared with the risk of withholding the index drug and related drugs.

Although, strictly speaking, drug allergy refers to an immunological drug reaction (eg, an IgE-mediated immediate or T cell-mediated delayed reaction), in this context, “allergy” is commonly used as a generic term for any ADR, whether an immunological reaction or a pharmacological side effect. Drug allergy labels may be conveyed by the medical record (including EHRs), the patient history, or medical alert jewellery. However, the label is frequently not supported by information on the nature of the ADR. It is noteworthy that information entered into the allergy field in the current iteration of My Health Record may be self-reported, with very little reaction detail and no medical validation required (www.myhealthrecord.gov.au/for-healthcare-professionals/what-is-in-my-health-record). While it is vital that true allergies are appropriately highlighted and the causative agents avoided, it is also important that useful drugs are not unnecessarily contraindicated by spurious overlabelling (Box 2).

In Australia, drug allergy is the most common cause of fatal anaphylaxis.8 Drugs implicated in anaphylaxis deaths are antibiotics, anaesthetic agents, non-steroidal anti-inflammatories and radiocontrast media (Box 1).8 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 (eg, abacavir, risk allele HLA-B*57:019) 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 (eg, ignoring medical alert jewellery); and

• misuse of terminology (eg, “sulpha” instead of a specific drug name such as sulfamethoxazole).

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

A recent multicentre study of 232 616 adult outpatients in the United States found that allergy documentation is often incomplete.10 In this study, for example, 15.6% of patients had a documented β-lactam allergy; of these, the specific culprit drug was mentioned in only 39.8% and the initial allergic reaction characteristics were documented in only 22.7%. The variability in documentation suggested that many patients are mislabelled.10 Similarly, an audit of drug allergy documentation in the United Kingdom identified that at least 20% of medical records and 24% of the medication charts contained inaccurate drug allergy documentation. The documentation improved after better education of junior doctors in regards to drug allergies.11

A national Australian survey identified significant knowledge gaps among clinicians, including drug allergy specialists and pharmacists.12 Of note, nurses made the majority of penicillin allergy notations (58%) in South Australia’s Enterprise Patient Administration System statewide EHR,13 indicating that educational initiatives may need to include all health professionals.

Effective education and prescribing guidelines have been shown to improve knowledge of drug allergy natural history as well as diagnosis and management.14 A clinical guideline that directs history taking and prescribing of antibiotics for low risk patients with an antibiotic allergy label significantly increased first-line antibiotic use and delabelling without increasing ADRs.15

In cases in which a patient might benefit from the drug, a review of the label requires information on the nature, severity, timing and circumstances of the original reaction, when available. Knowledge of drug reaction types and cross-reaction risks (Box 1) enables risk stratification. Immunology or clinical pharmacology consultation may provide additional expertise when required. If this assessment indicates that the label may be erroneous or no longer valid, then further evaluation by blood tests or skin tests (when available) and cautious challenge may refute or verify the label. Challenge testing should be undertaken judiciously, under close observation and monitoring, with due consideration of the likelihood and potential severity of any reactions that could occur. Patients and doctors may be reluctant to challenge due to fear and overestimation of risk,16 but this risk should be balanced by the potential benefit from the drug if it is tolerated.

Priority areas of knowledge to be addressed include:

• improvement in quality of the drug allergy history — date, exact drug, reaction type and severity;

• contemporaneous documentation of ADRs in medical records to preserve maximum information for future reference — this may require standardised record formats for EHRs;

• understanding of the mechanism, severity and cross-reactivity of drug allergy (Box 1);

• understanding of risk, including likelihood and potential severity of adverse reactions — a low likelihood of anaphylaxis or severe cutaneous adverse reaction is a more important contraindication than a higher likelihood of a non-dangerous ADR; and

• referral for investigation to verify or dismiss drug allergy labels — priority for useful antibiotics or drugs with strong indications and potential benefits.

Communication of 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. Furthermore, education of health care workers would improve the quality of information entered into such systems.