Allergies & Intolerance Use Cases

HL7 Patient Care Technical CommitteeLarry McKnight, MD

Use Case 1: Clinical Care of patients

• Allergy lists are entered and reviewed regularly as a routine part of clinical care.

• Entered, revised, updated, and clarified at various points in time:– Ambulatory H&P– Hospital Admission (nurse/physician/pharmacist)– Need to order medication that conflicts – Random times when patient recall of old allergy after

recorded or new adverse reaction noted.

• May be shared from other clinical information systems.– HIS to pharmacy

Use Case 1: Clinical Care of patients• The purpose of capturing allergies is to avoid inadvertantly

giving the patient a therapy that may cause harm.• The allergy list is used in:

– Clinical reasoning by humans – simple display of information– Automated decision support – active check during medication

ordering• Provider Order Entry System, Pharmacy, RIS

• Allergy lists typically require explicit negation to show "I asked"

• NKA • NKDA (drug)• NKFA (food)• Latex (Y/N)• IV Contrast (Y/N)

Use Case 1: Clinical Care of patients• Typically the important clinically important characteristics to record

are for each allergy are:– Allergen (typically one per allergy) Eg. Penicillin– Reaction (may be many per allergen) Eg. Hives– Severity (of each reaction) Eg. Severe– Onset of allergy in patient. Eg. When did the patient first note it.– Who is asserting it and when. Eg. The clinician– Certainty (see next slide)– Type of Allergen:

• Eg. Food, environment, medication.

• May be required for CDSS to work

– Type of "Allergy"• Eg. True Allergy vs Intolerance

– Status (eg recoreded in error or inactive)– Comments

Use Case 1: Clinical Care of patients• Other important notes about Clinical Allergies

– The allergen is generally only one component of the administered substance that was temporally associated with the adverse reaction, and it may be unclear what the actual allergen is. This is usually a clinical judgment based on and always starts with patient history.

– More certainty may be obtained by specific allergy testing such as skin testing or checking antibody titers.

– Allergens may cross react. – Many people use the term to include "intolerance" for any other reason the

patient doesn't want to have a particular medication given.– There are a relative few common allergens (eg Sulfa, Latex), but

theoretically any substances may be an allergen. Similarly there is a short list of common reactions, but a very long list of possible reactions including reactions that require additional constraints such as lighting (photo erruption).

– Typical patients will have NKDA. 2-3% will have 1 or 2 drug allergies, but some have >15.

Use Case 1: Clinical Care of Patients

• Examples of Recording and Updating Allergy lists: – While recording an Admission Assessment, the nurse

asks about what allergies the patient has. The patient says: "penicillin" The nurse asks about what kind of reaction the patient has. The patient says " I don't know, my mom told me not to take it when I was a kid"

– While capturing a history and physical the patient state to the physician "I think I have a reaction to the '-cillins' – I get a rash"

Use Case 1: Clinical Care of Patients

• More examples:– While seeing a patient in the Emergency room, the

admitting physician says to the patient "I see from the medical record you have an allergy to peanuts. What happens when you take peanuts?". The patient states "My face swells. I've been hospitalized 3 times for after eating even tiny amounts"

– Doctor needs to order an CT scan, and notices an allergy to IV contrast recorded. Patient states "I have no idea how that got there – I just had a CT with IV contrast last month without complications"

Use Case 2: Recording an Allergic Reaction Event or Adverse Reaction• A Problem/Diagnosis/Condition/Concern

– Can be used in Reason for visit.– Followed and tracked independently as a regular "concern"– Prompts for Further Evaluation and Treatment (eg Epinephrine, Steroids,

Antihistamines)– May still be mild or severe.

• Examples – Anaphylaxis after a bee sting– Decreased platelets while on Heparin (HIT)– Allergy to peanuts under evaluation– Seasonal allergy (pollen) / Angioedema (ACEI)

• allergen often unknown, unlisted.

• Should result in updated allergy list – if / when allergen suspect.

Use Case 3: Allergy Confirmation

• Skin testing– A controlled observation.

• Same assertion model -- just a more controlled environment.

• Greater confidence in results -- >85% sens and spec.

• Used for food, environment and medications.

• Type: Intradermal skin test, patch testing, …

– Contraindications • Severe reaction based on history

• Always start based on history

– Factors affecting results• On some other meds – eg. Steroids, antihistamines, …

• Skin conditions

• Do these need to be explicitly listed? (they are not currently in model)

Use Case 3: Allergy Confirmation

• Supporting results– Fluorescent enzyme immunoassay and RAST

(Radioallergosorbent Tests)– Food Challenges.– Endoscopy.– Platelet level dropping– A picture of the rash.

• Simple Observations– Does this need to be a general Clinical Statement?

Use Case 4: Adverse Reaction Recording/Reporting

• Allergy assertion is NOT made. – Simply an observation and recording of a reaction

• Examples:– Investigational medication with any adverse reaction.

RMIM-Revised