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Allergy Intolerance UseCase Storyboards May23

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Scope and Use Case

Allergy and Intolerances are some of the most commonly recorded information in the medical record. Clinicians record allergies and intolerances as a way to remind themselves and other providers to avoid giving substances that are known to potentially cause harm or discomfort to the patient. The process of identifying known adverse reactions and the believed causes for thme is a critical element of good clinical practice and is essential for safety and quality (Nehta).

Within the context of allergies, an _adverse reaction_ is a harmful or undesirable response after administration of an agent/substance. _Intolerance_ is a condition where the patient has been noted to have an adverse reaction and a judgment is made that the reaction was caused by a given substance. Administration of substances (in the form of ingestion, inhalation, injection, or direct contact) may result in adverse reactions which may be severe or mild, occur after variable lengths of time, and the relationship between exposure and the adverse reaction may be uncertain. Additionally, the noted exposure may be (usually is) to a mixture of complex substances. Additionally, many substances cross react, so that it may be a class of medications that cause problems. Therefore the assignment of causality of the actual relationship between the offending substance and the reaction is generally always uncertain to some degree.

Many make the distinction between a true allergy and intolerance. A _true_ _allergy_ is a type of intolerance with where the patient's immune system "hyper" reacts after exposure to that agent/substance or a chemically similar substance. True allergies typically result in a rash or swelling and may be life threatening. They also have defined treatments such as steroids antihistamines, or epinephrine. The classic example is a penicillin allergy.

Use Case 1: The clinical “Allergy” list

Pragmatically, true allergies and intolerances are often (usually) mixed in a separate section of the medical record. This section may be called “intolerances”, “alerts” or most commonly (and confusingly) called simply “allergies.” Different providers will have varying opinions on the need to specifically note minor intolerances to medications such as gastric upset in this section, however there is general agreement that true allergies and severe intolerances be recorded in this section and reviewed regularly. Some severe intolerances such as heparin induced thrombocytopenia do not follow the same physiologic pathways as true allergy but follow the same need for explicit and clear warning to prescribing or administrating providers and therefore are grouped in with “allergies.” Fortunately, the modeling for allergies and intolerances does not generally need to include details of pathogenesis, and is otherwise the very similar.

Logically, an allergy or intolerance is a type of medical condition. It is an observation (as judged by the clinician) that asserts the patient does or does not have a condition where a substance administration is felt to be associated with an adverse reaction. It may tracked like other medical concerns as a series of observations as further clarification or understanding of the nature of that allergy occurs. However, there are important distinctions between most medical concerns and allergies concerns. Because they are used as specific reminders not to administer or to alter therapy, they are generally called out as a separately tracked list. Other clinical conditions and patient data may also alter therapy as well (for example dose changes based on age or renal function, or contraindications to medications in certain medical conditions) but allergies are differentiated because they are recorded as the type of therapy to avoid rather than as conditions which usually can’t be avoided. Also, in many cases systems may require explicit review and specific negative assertions for various types of known allergens. For example, it is most common to see a section of a document or element of the EMR which explicitly states that the patient does not have any known allergies or any known drug allergies. The degree of granularity for specific negation is variable from specific application to application or from use case to use case. For example, many systems record explicitly that the patient is not allergic to latex or IV contrast.

In general, obviously harmful substance administrations such as poisoning or overdoses are not included in allergy/intolerance lists because there is generally never intent to treat the patient in such a manor. Similarly, seasonal or pet allergies which share many of the same underlying pathophysiology as true allergy are generally not recorded in allergy lists because there is generally not concern that these substances will be administered as therapy planning. Food allergies are variably included in this list but typically are included since diets may be ordered or prescribed and many medications or immunizations may include food substances. Most notably many immunizations are grown in eggs.

Data Capture:

Allergies/Intolerance lists are typically reviewed at many points of patient care. For example, physicians typically review patient allergies when they first see a patient or perform History and Physicals. Nurses typically have a similar intake assessment where allergies are reviewed as do pharmacists. Typical use patterns typically involve a review rather than capture of new allergies because allergy information is considered to be important by a wide variety of people and so it is frequent that some records are available which provide this information. For example a nurse may review a list of the patients allergies from transfer records when he/she does their intake assessment, and a physician may review the nurses list with the patient when he/she does their history and physical.

It is also common that allergy lists are reviewed and updated in the course of care when new information is available. For example, it may be noted that the patient has a new suspect allergy when noted to have an adverse reaction after exposure to a medication. Similarly there is often review and correction a result of need to challenge the certainty that the allergy exists. For example an allergy to Penicillin may be noted. This may persist for quite some time before the patient actually needs antibiotics, and further questioning may reveal that the reaction happened many years ago and that patient is unsure about specifically what happened. Cautious trials of therapy or even further verification testing may proceed as a result. Additional clarification details may be appended such as “patient has tolerated cephalosporins in the past” (i.e. cross reactivity has been ruled out) or the allergy may even be marked as erroneous.

Allergies and some intolerances may be supported by evidence such as allergy sensitivity testing or serology tests.

Data Use:

Allergy information is useful for a variety of use cases. First, it is used in the human review of allergy information. Patients may forget or may be unable to indicate allergy information. Indeed even the same provider may have difficulty remembering a patients allergies as the patient moves through the continuity of care. As a result it is allergy information is usually provided from provider to provider on any patient transfer, discharge, or referral. This occurs through paper documents, simple storage in an EMR where both clinicians share the same EMR, or exchange between clinical information systems when the clinicians use different systems. Electronic transfer of this information may be either through structured documents, messages, or queries depending on particular use cases and or system capabilities.

Allergy data always includes some representation of the allergen, however also should ideally include the reaction with or without severity, then additional details including when the event occurred or supporting details. The data capture is often incomplete, however and even the allergen may be hazy. For example the patient may only remember that they are allergic to a “-cillins” Allergy information needs to be codified and computer processable since many systems use and exchange allergy data for the expressed purpose of drug order to allergy checks, and may require allergy information to be assessed. Many systems also require statements about the status allergy review within a given time period, thus it is important to include even updates even when the assertion is simply to repeat that no allergies are known to exist.

In some cases allergy information is used for reporting to external agencies.

Use Case 2: Reporting of Adverse Reactions:

If the assertion of between an allergen and a reaction cannot be established, the reaction may still be clinically relevant for reporting purposes. Drug trials typically record this information independent of the separately from allergies and expressly wish to avoid assigning the judgment of allergy prematurely. Details of adverse reaction within this context are usually more complete. Modeling should be similar, however and adverse reactions noted in this context may later be used to establish or support the judgment of allergy.


Storyboard 1: Physician adds and Allergy from patient history

Precondition: Patient Adam Everyman is seeing Dr. Patricia Primary for evaluation of a cough. In the process of recording Mr. Everyman’s history Dr. Primary states a history of no known drug allergies NKDA. After reviewing Mr. Everyman’s history and exam findings, Dr. Primary decides that Mr. Everyman probably has a chronic bronchitis and should be referred to the a pulmonologist Dr. Bob Breathright for further evaluation.

Activities: Dr Primary creates an electronic referral letter which includes the allergy information embedded in the document. He sends this data to Dr. Breathright as part of the electronic referral documents. Alternative flows include Dr. Primary has posting documents or the allergy information to a central repository and Dr. Breathright querying the repository. Yet other flows might have Dr. Breathright query Dr. Primary’s EMR directly.

PostConditions: Dr. Breathright accepts the referral and has the relevant allergy information.

Storyboard 2: Physician updates allergy information and sends it on transfer of care

Precondition: Dr. Breathright, a pulmonologist is seeing Mr. Everyman in his office after a referral from Dr. Primary. Dr. Breathright reviews the allergy information with Mr. Everyman noting the prior assessment of NKDA from Dr. Primary. On review, Mr. Everyman recalls, that he failed to mention an allergy to Penicillin. Mr. Everyman cannot recall what reaction happened, only that his mom told him as a child not to take it.

Activities: Dr. Breathright records the updated allergy to penicillin in his EMR. He includes this information in his consult note back to Dr. Primary. Alternative flows include Dr. Primary receiving message of the updated allergy information via message sent either directly, or forwarded from the central repository

Post condition: Dr. Primary receives notification of the updated allergy information, and can update his system appropriately.

Storyboard 3: Physician reviews and reassert allergy information

Precondition: Mr. Everyman calls Dr. Primary with complaint that he has a fever and is coughing copious amounts, mostly green in color but sometimes including streaks of blood. Dr. Primary advises Mr. Everyman to go to the Emergency Room for evaluation.

Activities: Dr. Primary prepares an emergency department referral which includes allergy information as it’s recorded from his EMR. In the emergency room, Nurse Carrie Careful reviews allergies with Mr. Everyman. Mr. Everyman is coughing severely and finds it hard to speak without coughing. The history goes a little faster because she has seen the referral note from Dr. Primary that includes the penicillin allergy. She quickly confirms this with Mr. Everyman with the statement “I see from your records that you have an allergy to penicillin, is that correct?” Mr. Everyman nods, yes. She asks about other allergies to which Mr. Everyman nods, no. She notes the Penicillin Allergy in her nurse assessment. The system prompts explicitly for Latex and IV contrast. She reviews those with Mr. Everyman, who again nods no. She records “no latex allergy” “no IV contrast allergy”. Dr. Eric Rescue, the physician on call in the emergency department, also reads Nurse Careful’s assessment and confirms this with Mr. Everyman. Dr. Rescue decides Mr. Everyman has pneumonia and needs to be admitted. Dr. Rescue reasserts the assessment of penicillin allergy in his note and prescribes antibiotics that don’t cross react with penicillin, because he sees the allergy.

Post Condition: Drugs that might cause adverse reactions are avoided. The hospital information system has a correct and updated allergy list. Important negations are noted.

Storyboard 4: Clarification of allergy information and use for drug/allergy checking

Preconditions: Mr. Everyman has been admitted to the hospital and has had a single dose of antibiotics in the emergency room. Dr. Primary has written for Levofloxicin as an alternative to the standard formulary choice of Cefuroxime. Cefuroxime is a type of Cephalosporin. Cephalosporins generally have about a 10% cross reactivity with Penicillin. Culture results return back that the organism in Mr. Everyman’s sputum sample are growing XXX which is resistant to Levofloxicin, but sensitive to CefXXX. Dr. Primary asks Mr. Everyman more about the allergy. Mr. Everyman admits that he has had other Cephalosporins in the past without any problem.

Activities: Dr. Primary discontinues the order for Levofloxicin, and adds an order for CefXXX. The system generates an alert indicating that there is a known cross reactivity between CefXXX and the patients allergy to penicillin. Dr. Primary indicates clarification about the fact that Mr. Everyman has had other cephalosporins in the past without difficulty.

Post condition: The system places the order, and also updates the pharmacy system. The allergies in both systems are updated to reflect the comment that cephalosporins are OK.

Storyboard 5: Physician requests skin testing for penicillin

TODO:(there is need to actually use pcn. Infectious disease is consulted and recommends skin testing. Patient is not allergic. Records updated to reflect that patient really is NKDA)

Storyboard 6: Reporting of new adverse reaction.

TODO:(?reason started on investigational drug. Nurse notes develops rash. New allergy noted. Reporting system (query)

Storyboard 7: Patient report of Food Allergy

TODO:(eg report of egg allergy, need for vaccination, system alerts cultured in egg)

Storyboard 8: Physician Evaluates a new Rash believed to be allergy: (use case 2).

Precondition: Dr. Patricia Primary is viewing the EMR of Patient Everyman. Mr. Everyman has come to clinic to have a rash evaluated. The allergy list is empty.

Activities: Dr. Primary elicits the patient history. The patient has visited an Indian restaurant for the first time and was exposed to many new spices. The patient wonders whether the rash is due to the spices. Dr. Primary examines the rash and notices the typical linear pattern associated with a plant exposure. She questions the patient further and finds the patient had been working in the garden earlier in the week. The patient has never had cedar wood chips. Dr. Primary assures the patient that allergy to Indian spices is unlikely to be the cause of this rash. Rather, Dr. Primary identifies probable cedar wood chips and educates the patient on the disease. She places the problem “rash – probably due to cedar wood chips” on his problem list and gives the patient a prescription for Prednisone. She adds cedar wood chips to the allergy list.

Post-condition: Mr. Everyman has progress notes, findings, impressions, care plans, and a populated allergy list in the EMR that are captured in a manner that allows navigation from one related data item to the next. Specifically, the user is able to navigate from the current name of the allergy on the allergy list to the string of observations and treatment activities associated with management of that allergy over time. Additionally, the user is able to navigate from a data item to the allergy management programs supported by the data element.

Storyboard 9: Physician notes severe Intolerance

TODO: (eg presentation to ED with anaphylaxis)