| Recommendation |
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|---|---|
| Relative values of different outcomes | The following outcomes were identified by the GDG as important for decision-making: mortality, number of repeat drug allergic reactions, length of hospital stay, acute admission or readmission into secondary care, number of contacts with healthcare professionals, inappropriate avoidance of drugs, health-related quality of life. The group noted that no evidence was identified that directly addressed the effectiveness of algorithms in terms of the clinical outcomes specified, but the evidence instead focused on causality criteria with associated scores in developing an algorithm. |
| Trade-off between clinical benefits and harms | The group agreed that the benefit of an algorithm for the assessment of signs and symptoms is that it can help in identifying whether the reaction observed is likely to be caused by a drug. However, in the group's opinion, the key potential harm of recommending the use of an algorithm to people with a suspected drug allergy is the poor predictive value provided by algorithms. Specifically, the lack of absolute prediction of whether the person presenting with a suspected drug allergy is experiencing an allergic reaction or not and the risk of clinicians providing false reassurance was a key concern. The GDG noted that signs and symptoms of drug allergy in children may differ from those in adults, and typical patterns suggesting an allergic reaction to a drug may not apply in a child's case. For example, non-specific rashes are more common in children and these are usually not due to drug allergy, whilst severe cutaneous reactions are less common in children. The GDG also recognised that people of certain ethnicities and those with certain comorbidities such as cystic fibrosis or HIV are at higher risk of allergic reaction to specific drugs or drug classes. |
| Economic considerations | No relevant economic evidence was identified. The GDG did not prioritise this question for original economic analysis. The GDG agreed that the proposed assessment would most likely be carried out as part of an initial GP (or other non-drug allergy specialist) assessment, but could take longer than current practice (which generally involves noting an adverse reaction, rather than assessing the reaction and investigating the possibility of an allergy). Therefore, there may be a small increase in initial cost. However, the GDG felt that appropriate assessment would be of great clinical benefit to the person with a suspected drug allergy, as it would be likely to improve the accuracy of diagnosis. Accurate diagnosis will improve quality of life, and reduce the later costs associated with incorrect labelling of drug allergy (such as those incurred by patients who are unnecessarily given alternative second-line drugs, which are often more expensive and less effective than the first-line option). Appropriate assessment using the recommendations above will therefore assist selection of the appropriate treatment strategy for each person with a suspected drug allergy, and therefore promote economic efficiency of the clinical pathway. The GDG agreed that carrying out the assessment when the patient first presents with a potential allergic reaction would lead to the best clinical outcomes, as details of the reaction are likely to be documented more accurately than if left to a later stage. Overall the GDG agreed that the benefits (improvements in quality of life and reduced future costs) of the signs and symptoms checklist would outweigh the small upfront cost of a longer initial consultation. |
| Quality of evidence | The aim of the review of algorithms was to identify common signs and symptoms that indicate whether a person may have a drug allergy. The evidence showed that a number of the algorithms did not specify such patterns but focused on the types of questions that physicians need to consider when trying to identify whether the drug caused the reaction. The NICE quality assessment tool for systematic reviews was applied to the published systematic review. A further tool was designed to assess the quality of algorithm studies added to this review. The studies included in the review were assessed as good to moderate quality. However, since the algorithms that were reviewed did not always address signs and symptoms directly, the evidence was given less value in drawing up the recommendations. The GDG advised that not all the algorithms reviewed were applicable to primary care as they required too much time for a GP to use during standard consultations, required challenge testing, or did not result in a final clinical decision for managing a patient. The GDG noted that the algorithms included in the review looked at adverse drug reactions and not at drug allergy specifically and were not assessed for effectiveness in clinical settings. |
| Other considerations | The GDG concurred with the conclusion of the Agbabiaka3 systematic review that clinical judgement is still required when using an algorithm as a decision-making tool, and that no single algorithm is accepted as a gold standard. The GDG noted that the Naranjo121 and Kramer86,87 studies were the most commonly referred to within the literature, and the study by Jones which compared the 2 favoured the Naranjo algorithm.121 The European Network for Drug Allergy questionnaire (Bousquet 200918) was a large study designed for use by GPs and was assessed as being of high quality. However, no study had addressed how effective these tools were within a clinical practice setting, and the GDG thought that none of the algorithms were practical for use in general practice or other non-specialist settings. Most of the studies did not assess the clinical effectiveness (that is, directly leading to improved patient outcomes) of algorithms against each other or against other methods of diagnosis. This evidence would have been included but no further studies were identified. The GDG noted the difficulty of capturing the wide range of drugs and reactions to drugs in a single decision-making tool, and that as drug allergy is a subset of adverse drug reaction, it was difficult to identify drug allergy using an adverse drug reaction questionnaire such as the tools produced by Kramer86,87 or the European Network for Drug Allergy (ENDA).18 The GDG suggested alternatives which may be more effective, such as checklists, pathways or flow charts. The GDG questioned the helpfulness of a probability score as used in the ENDA questionnaire18 because it does not lead to a decision for the clinician. However, the group did think a checklist of common symptoms may be helpful and further agreed that any decision tool should ideally be short, easy to use and include a score that would determine the action to be considered by the clinician. The group cited the use of the CHADS2 system120 (congestive heart failure, hypertension, age ≥75 years, type 2 diabetes and previous stroke or transient ischemic attack), which is used as a predication rule for atrial fibrillation. Although no suitable scoring system was identified from the review, the development of a validated algorithm or decision rule including a scoring system for use within non-specialist settings would be a helpful guide in assessing and managing people who have had a suspected allergic reaction to a drug. The GDG agreed the common signs and symptoms listed in the ENDA study18 could be adapted and used as a basis for the recommendations. The GDG acknowledged the questions used within the Naranjo paper are for use within a specialist setting,121 however they believed some of these were also relevant for use within a non-specialist setting and would be a helpful addition to the recommendations as a part of the initial assessment and decision-making process undertaken by the clinician. Providing timings of when signs and symptoms are likely to occur after exposure to a drug was thought to be helpful when making an assessment. The group arrived at the timings given in the recommendations through informal consensus based on their clinical experience and knowledge of the literature in this area. The GDG noted that currently, adverse reactions are listed in the information provided with most drugs and these reactions are categorised from common reactions, to less common reactions and rare reactions. |
Note that these boxes describe common and important presenting features of drug allergy but other presentations are also recognised
From: 6, Assessment
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