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Allergic,

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A patient who suffers from an allergic, hypersensitive, or intolerant reaction or disposition with a known cause should be protected by the healthcare providers from any repetitions of these episodes.

Healthcare professionals at the point of care should have access to known allergic, hypersensitive, or intolerant reactions or dispositions in the clinical record. Health information systems should share this information and implement systems to alert the healthcare team of possible risks automatically.

Allergic, hypersensitive, and intolerant reactions can be avoided by preventing the prescription or and administration of, or exposure to known trigger substances. The proper documentation of known allergic, hypersensitivity, or intolerance episodes is critical to making this knowledge available at the point of care and supporting decision-making that would prevent future situations. Information needs to be recorded with the right level of detail and context to support these processes. 

This page summarizes the key use cases covered by this guide. See section 4.3 for detailed examples. 

Use Case 1: Documentation of Information Related to Allergy, Hypersensitivity, and Intolerance

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Scenario 1.1: Documentation of an adverse reaction to a drug substance

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A physician sees a patient in clinic for routine outpatient care.  Recently the patient was prescribed penicillin V 500 mg orally two times daily x 10 days for streptococcal pharyngitis. He tells the physician that he has developed hives the previous week and on examination, the physician confirms the presence of generalized hives. He records this in the patient record as an Observation.

A review of systems fails to reveal any other causes and the physician believes that the patient may be having an urticarial reaction to penicillin. He has lingering uncertainty about this and tells the patient to stop the penicillin and employ diphenhydramine for relief. He schedules him back in a week for follow-up and when recording his note for the visit, he adds to his assessment in the problem list: “Moderate urticarial reaction, possible penicillin allergy”.

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Healthcare providers should be able to accurately record the details of a patient's adverse reaction to a drug substance. This information includes the drug substance involved, routes of administration, dosage, signs, and symptoms produced by the reaction, time frames, etc., allowing for clear and consistent documentation and communication between healthcare providers. This can improve patient care by facilitating a more accurate understanding of the reaction and facilitating the identification of potential risk factors. Additionally, the use of SNOMED CT can support research and data analysis on adverse drug reactions.

Scenario 1.2: Documentation of drug allergy in the allergy list and use as alert to provider

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Several years later, the patient from scenario 1.1 who has since received an aortic valve replacement is seeing another physician within the organization for consultation on antibiotic prophylaxis for an upcoming dental procedure. The second physician decides that a penicillin class antibiotic is appropriate for the patient.  

When the physician creates an order for amoxicillin 2 g orally as a single dose and commits to the electronic prescription, an alert appears which requires a response by the physician warning him of an allergy history to penicillin. The substance-based alert is generated by the EHR drug-disease interactions software, which uses the Allergy list as a reference. As the patient has not received penicillin class antibiotics for several years, the physician decides to refer the patient to an allergy specialist for clarification of current status of penicillin allergy. 

The specialist performs skin testing for penicillin allergy, the results of which are positive. The patient is confirmed as penicillin allergic and the results of the testing are documented in the patient’s medical record. 

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SNOMED CT can be used to document drug allergies in the allergy list and serve as an alert trigger to providers. This will allow providers to quickly and accurately identify drugs that a patient may be allergic to, for instance as they prescribe. SNOMED CT is used to identify potential allergy triggers in the patient's medical history and assist providers in determining the safest and most effective treatment options for the patient.

Scenario 1.3: Documentation of a food intolerance

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A 34-year-old female is seen by her primary care provider for complaints of abdominal pain, bloating and change in bowel habits within hours or a few days after ingesting whole wheat bread. In addition, she complains of feeling tired but denies itching rash or wheezing. Those complaints are entered as observations in the EHR.

Due to a family history of celiac disease, tissue transglutaminase IgG and IgA are ordered which are negative. The patient is also referred to a gastroenterologist, who performs an endoscopic biopsy, which is negative for celiac disease. (Both of these examination results can be recorded in the EHR as a FHIR observation using LOINC codes).

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Healthcare providers should be able to record the details of a patient's food intolerance accurately. This information includes the type of food, examination results, signs, and symptoms produced by the intolerance, time frames, etc., allowing for clear and consistent documentation and communication between healthcare providers. This can improve patient care by facilitating a more accurate understanding of intolerance events and facilitating the identification of potential risk factors. Additionally, the use of SNOMED CT can support research and data analysis on food intolerance, food allergies and cross reactivities.

Scenario 1.4: Documentation of animal allergy

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A physician sees a patient for the first time in clinic for routine outpatient care.  The patient tells the physician that he has begun to experience asthma symptoms.  The physician runs some blood tests and a series of skin tests, which demonstrate an intense reaction to the house dust mite, Dermatophagoides farinae protein with high IgE antibody levels. 

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Healthcare providers should be able to record the details of a patient's animal accurately. This information includes the type of animal, exposure, examination results, signs and symptoms produced by the allergy, time frames, etc., allowing for clear and consistent documentation and communication between healthcare providers. This can improve patient care by facilitating a more accurate understanding of his/her environmental allergic events and facilitating the identification of potential risk factors /situations. Additionally, the use of SNOMED CT can support research and data analysis on animal allergy.

Scenario 1.5: Documentation of allergy to non-medicinal substance cross-reacting with a pharmaceutical

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A patient’s mother reports to their child’s physician that the child reacts violently to eating peanuts with symptoms that include generalized hives, wheezing and hypotension requiring use of epinephrine for resuscitation.  The physician obtains a blood test which documents high levels of IgE antibody against the Arachis h2 peanut protein which is found in unrefined peanut oil (Arachis oil) - the sensitizing agent for clinical peanut allergy. Ara h2 is associated with a risk of severe reactions to peanut.  The physician records a peanut allergy in the EHR with anaphylaxis, hives and wheezing as reaction symptoms, records a criticality of high and reaction severity of ‘severe’.  

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SNOMED CT can be used to document non-medicinal substance allergies in the allergy list, which can cross-react with ingredients of medications or be an excipient in medications and thus serve as an alert to providers when prescribing a drug treatment. This will allow providers to quickly and accurately identify drug classes or specific branded drugs or drug forms a patient may be allergic to based on previously recorded allergies to non-medicinal ingredients. SNOMED CT is used to identify potential allergy triggers in the patient's medical history and assist providers in determining the safest and most effective treatment options for the patient.

Scenario 1.6: Documentation of allergic reaction to other non-medicinal substances

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A licensed nurse presents to her personal physician for recurring problems of a generalized rash and itching.  She works in an intensive care unit and is constantly handling chemicals, disinfectants, assisting in surgical procedures and performing catheter cares for her patients.  As a part of the health history, she noticed that she had an eruption on her hands after handling latex catheters.  Additionally, she reports a serious allergic reaction to papaya in the past and has been careful in the fruits she eats as a consequence.  The clinician suspects a latex allergy cross-reacting with foodstuffs and orders IgE testing for Hevea latex antibody.  The serology testing is strongly positive and the clinician advises the nurse of his findings with warnings about other foods, which may cross react.  While documenting the clinical encounter, he records a latex allergy in the allergy list.

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Healthcare providers should be able to record allergic reactions to other non-medicinal substances accurately. This information includes the type of non-medicinal substance, examination results, signs, and symptoms produced by the reaction, time frames, etc., allowing for clear and consistent documentation and communication between healthcare providers. This can improve patient care and general life by facilitating a more accurate understanding of allergic reactions and facilitating the identification of potential risk factors, situations or products to avoid in everyday life or protection equipment needed during professional exposure. Additionally, the use of SNOMED CT can support research and data analysis on allergic reactions.

Scenario 1.7: Documentation of ‘No Known Allergies’

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Healthcare providers should be able to record when a patient reports that he/she has no allergy history, with the data and time of the report.

Use Case 2:  Sharing of Information Related to Allergy, Hypersensitivity, and Intolerance

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Scenario 2.1: Sharing adverse reaction data

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The patient from scenario 1.1 is planning a vacation with his family consisting of a cross-country camping trip.  In preparation for travels, he speaks to his physician in hospital A and obtains an electronic summary of his healthcare record on a flash drive for himself, his wife and children. His physician informs him that the summary software includes an electronic ‘reader’ as well as a standard format that can be imported into another EHR for patient care.  Their vacation unfolds happily until, many miles from home the patient experiences an episode of right ear pain and is taken to a local emergency room in hospital B.  He provides the flash drive with his electronic record summary to the emergency room physician whose hospital employs an EHR which can accept FHIR extracted electronic record summaries for integration into the on-site health record system.  The emergency room nurse loads the flash drive and accepts the electronic copy of the problem list, allergies and medication list into the on-site record.  The software extract manages the differences in information model design between EHR vendors by crosschecking the allergy list with information in the problem list and encounter diagnosis.

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Electronically-stored allergy, hypersensitivity and intolerance information information should be semantically interoperable to enable sharing of information across system, organization and geographic boundaries.

Use Case 3:  Supporting the Implementation of Decision Support Systems

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Scenario 3.1: Potential adverse reaction alerts

Electronic health records should be able to leverage the stored information to run clinical decision support systems to alert clinicians of potential adverse reactions due to allergy, hypersensitivity and intolerance.