Allergy & Intolerance Drug Sub-project

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Purpose

Produce a list of unique substances and multiple substance medications used in allergy & intolerance lists, ordered by frequency of incidence. This list will support the use of common elements for data capture and validation of data exchange. This list is not intended to prevent the recording of unusual substances where necessary, whether by code or text.

We would like to provide a set of standard coded identifiers for these substances. The codes for such a list would need to be free, readily available, and accepted for use by international stakeholders.

Note that the criterion is clinical use, not chemical specificity. I.e., if all we know is that the patient reports an allergy to "fish," that's what we can record. Similarly, if a patient has a reaction to percocet, and the clinician doesn't have evidence that supports identification of a specific ingredient, then "percocet" is what we know.

Goal

• A list of substances ordered by frequency of incidence, with frequency ratios
• Identifiers for these substances, using freely available standard identifiers

Plan

• Confirm goals
• Assess assets
• Evaluate gaps
• Fill gaps

Open questions

Scope & Governance

1. Stewardship: who owns and maintains the list? Patient Care? Vocabulary? Someone else?
   1. For now, Patient Care
2. How do we harmonize frequency thresholds for drugs (1000) & food (lower)?
3. Should we provide a single mapping per code or a multiple mapping table?
   1. Tentatively, one. More later if requested.
4. How do we present guidance
   1. False categories (seafood)
   2. Mislabeled categories (iodine contrast vs. high osmolality contrast)
   3. Distinguishing allergies from side effects (e.g., denying azithromycin due to erythromycin sensitivity better managed by contraindications)
   4. Criticality - to what extent can we prioritize substances based on likelihood that sensitivity may be critical?
5. Should we provide a single value set for substances or multiple sets for drugs, food, other?

Domains

1. How do we identify biologics, vaccine components
   1. Vaccine: Organism? Protein? Product?
2. How do we identify herbals, supplements
   1. Proposed: As other medications, if in RxNorm
3. How do we identify environmentals
   1. Proposed: SNOMED CT, which supports classification (e.g., 'wasp venom' vs many species-specific terms in UNII).
4. How do we identify supply items (latex, adhesive)
   1. Latex: RxNorm
   2. Adhesive: SCT classifier 418920007 |Adhesive agent (substance)|
5. Food/Drug items: record as both or as one?
   1. Eggs, lactose, fish oil, caffeine, alcohol
   2. Are Sulfites & Nitrites food only?

Specific Questions

1. Iodinated contrast media
   1. Use "high osmolality contrast media"?
   2. In addition to 'iodinated contrast media' or instead?
2. Penicillins
   1. Can we identify truly cross-reactive subgroups?
   2. Beta lactams, extended spectrum, beta-lactamase resistant penicillins, amino, carboxy, Ureido, etc.?
3. Negatives: we have NKA, NKDA, NKFA. Do we need NKEA, NKFDA?
   1. Frequency is the criterion.
4. Morphine derivatives. Morphine and related. List as Morphine and let drug check worry about x-reactivity?
5. Salicylates.
   1. A class including topical salicylates and ASA?
   2. Or distinguish topical salicylates, ASA (any other systemic salicylate?)

1. influenza virus vaccine, inactivated. Etc. CVX seems too specific, but no general terms available for components.
2. Tetanus. tetanus toxoid vaccine, inactivated?
3. "narcotic analgesics": Opioids?
4. Estrogens. Class or IN.
5. ASPIRIN BUFFERED.
6. Nitrates, Organic
7. Nickel, nickel sulfate
8. POVIDONE IODINE.
9. iodinated glycerol
10. aloe vera topical
11. VACCINES
12. quinine and analogues
13. Tegaderm. Adhesive, or this product?
14. sulfa topicals
15. Simvastatin, atorvastatin, pravastatin, rosuvastatin: distinct or cross-reactive?
16. Tape: How many kinds of tape do we need - plastic, paper, surgical, adhesive, medical, cordran, silk, steristrip, opsite, transparent? Or is this really about adhesive?
17. Is adhesive one substance or do brands differ?
18. Metal, nickel, trace metals? Top 500 has only nickel sulfate.
19. Do we need acetaminophen, aspirin, naproxen or does NSAIDs do the job?
20. Need to specify route for certain substances? (topical vs IV iodine, salicylates)
21. probably under threshold
    1. Beta Lactamase Inhibitors.

Closed Questions

1. Include substances only, or also null and negative values?
   1. Use is the criterion: include what is used. Agreed 10/19
   2. Specific negatives are rare; we anticipate two (nka & nkda).
2. How do we confirm quality?
   1. Process
      1. Acquire maps.
      2. If count(maps) > 1 and they agree, status is ok.
      3. If count(maps) < 2, acquire more maps.
      4. If count(maps) > 1 and they disagree, review.
3. Encode and then combine, or combine and then encode?
   1. Encoding is required to combine
4. How do we weight lists?
   1. Use filtered rankings to assess divergence, but no weighting in frequency list.
5. Rank all substances from contributed lists, or only those to a chosen level (97%, 99%, etc.)?
   1. Identified substances with counts > 500 (individually ~0.0017%; aggregate 0.71%)
   2. Actually, 1000. 4/19/17.
   3. Include frequency ratios in resulting list; users may choose their own thresholds.
6. Salt forms of medications are not relevant to the purpose of this list. Incidences recorded as salt forms should be summed to the incidence of the general form (e.g., codeine sulfate as codeine).
   1. Salts in solution have limited effect on the active moiety. This does not mean that an intolerance reaction dependent on a salt is not possible; only that it is not common enough to merit inclusion in this list.
7. Route can be significant.
   1. Enterally administered aspirin does not cross-react with topical salycilates. Topical salycilates should be specified as topical. Similarly, sensitivity to topical iodine preparations is not cross-reactive with intravenously administered iodine.
      1. confirm cross-reactivity. whether iodine can be the problem is a different question.
8. What system(s) should be used for encoding?
   1. Assumption: do we need to choose, or can we provide a list of substances with all pertinent code assignments?
   2. Criteria
      1. Maximal coverage of identified requirements
      2. Ability to add missing items
      3. Freely available
      4. International
   3. Candidates
      1. SNOMED CT: substances, classes; mixtures only as products. Licensing issue.
      2. RxNorm: substances & mixtures. No license issue, but US realm.
      3. NDF-RT: classes only. Class definitions problematic.
      4. UNII: substances only. US realm. no relationships (e.g., of salts)
      5. ATC: classes only. Class definitions problematic.
      6. INN: no access to list; tbd
      7. Proposal to use whatever G-SRS chooses to use. Will evaluate when available.
   4. Answer: for now, RxNorm (substances - IN & mixtures - PIN) and SNOMED CT (classes) meet our needs. When G-SRS can provide data for comparison and testing, we can confirm whether it also meets our needs and decide whether to map or replace the US realm list.

Minutes

9 May 2017

12 April 2017

8 March 2017

2 February 2017

11 January 2017

28 December 2016

14 December 2016

16 November 2016

2 November 2016

19 October 2016