Allergy & Intolerance Drug Sub-project questions

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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?
   1. In VSAC, the sets have values from a single system, so we are looking at several value sets, possibly with a "grouping" value set to tie them together.

Domains

1. How do we identify biologics, vaccine components
   1. Vaccine: Organism? Protein? Product?
   2. TNF
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. Negatives: we have NKA, NKDA, NKFA. Do we need NKEA, NKFDA?
   1. Frequency is the criterion.
2. Iodinated contrast media
   1. Keep 'iodinated contrast media' to support legacy use, if no other reason
   2. Consider adding "high osmolality contrast media"?
   3. See sheet of iodine & media terms here
3. Penicillins
   1. Can we identify truly cross-reactive subgroups?
   2. Beta lactams, extended spectrum, beta-lactamase resistant penicillins, amino, carboxy, Ureido, etc.?
4. "narcotic analgesics": Opioids?
   1. Morphine derivatives. Morphine and related. List as Morphine and let drug check worry about x-reactivity?
5. Need to specify route for certain substances?
   1. Salicylates.
      1. A class including topical salicylates and ASA?
      2. Or distinguish topical salicylates, ASA (are there other systemic salicylates?)
   2. Iodine: is povidone always topical? (Can be ophthalmic, but below threshold) Is it ever systemic?
   3. aloe vera topical - always?

1. Estrogens. Class or IN?
   1. propose "class"
2. ASPIRIN BUFFERED. Aspirin? Or ASA + Al(OH)3 + CaCO3 + Mg(OH)2?
3. iodinated glycerol: which is it? Mixture?
4. Tegaderm.
   1. Propose: hydrocolloid (substance)
5. Simvastatin, atorvastatin, pravastatin, rosuvastatin: distinct, or cross-reactive "statin"?
6. 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?
   1. Is adhesive one substance or do brands differ?
7. Metal, nickel, trace metals? Top 500 has only nickel sulfate.
8. Do we need acetaminophen, aspirin, naproxen or does NSAIDs do the job?
9. Beta Lactamase Inhibitors: no class in SCT

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 - MIN) 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.