Drug Allergy Substance List HL7 Patient Care & Vocabulary Work Groups Saved 26-Apr-17

Problem Allergy substances are recorded in many different ways. A patient’s record may be difficult to read due to redundant records. Order check rules may not recognize relevant values. Existing specifications provide very broad guidance. They don’t support a usable human interface. Message validation is not feasible.

Goal Produce a relatively concise list of medications (substances, classes, & mixtures) frequently used in allergy & intolerance lists. Note that the use case is patient safety, not pharmacovigilance.  This list will support the use of common elements for data capture and validation of exchanged data. 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 desiderata for such codes (in addition to semantic accuracy) would be free of charge, readily available, and accepted for use by international stakeholders.

Data: Allergy Records VA, Dutch data pending Cerner DoD IMHC KP NE   Cerner DoD IMHC KP NE total [unassigned] 297,392 7,433 30,153 38,470 5,384 378,832 biologic 4,646 102 1,341 6,089 environmental 1,034,189 28,447 76,114 139,709 4,319 1,282,778 food 1,582,115 58,643 69,437 379,131 4,621 2,093,947 medication 16,333,129 509,605 517,802 3,131,045 107,267 20,598,848 medication class 6,157,854 287,107 237,751 1,140,079 29,081 7,851,872 negation 32,447,511 1,874,531 3,318,006 1,999,170 5 39,639,223 Null 60,058 87,815 9,322 1,115 158,310 supply 1,126,985 818 27,677 116,997 4,971 1,277,448 vaccine 207,981 7,006 7,403 41,039 919 264,348 59,251,860 2,861,405 4,284,445 6,996,303 157,682 73,551,695 VA, Dutch data pending

Data: Medication & Class Allergy Records Source Substance Strings Records, Cerner 10,069 22,492,668 DoD 7,127 796,712 IMHC 1,613 755,553 KP 2,370 4,272,440 NE 1,541 136,348 Aggregate 12,270 28,453,721

Term Frequency & Incidence

Mapping Threshold 28,453,721 records for medication & medication class

Map Questions: Unclassified Strings

Top 20 by Institution Trial mapping

Mapping Salts Substance Count Category mapName mapCode mapSystem mapSource QAstatus Abacavir 2733 medication abacavir 190521 RxNorm DoD - outbound CHDR 0 - raw 911 IMHC KP - HL 387005008 SNOMED CT Cerner ABACAVIR SULFATE 409 abacavir sulfate 221052

Issues Mapping unclassified strings Salts Identify a threshold for effort Most items below the threshold are unclear anyway Salts Is one answer right for all salts? For all “precise ingredient” refinements? Boundaries with herbals, vitamins Vaccines, Biologics CVX seems too specific RxNorm offers some more generic vaccine substances, but they are not connected to products What are likely reactive components – organism markers or stabilizers, preservatives, & adjuvants? How to handle other biologics – blood, TNF

Class issues Which ones are real & which are not; how to handle exclusions E.g., Iodine & contrast media If these are cross-reactive classes, do we also need more specific members? Pencillins / Pen G NSAIDS / Acetaminophen Opiates / Codeine Salicylate / Aspirin How are classes to be defined? ATC/NDF enumeration SNOMED CT concept Other approach

Class Options SNOMED CT: model in flux NDF-RT, ATC NDF-RT Classes based on principles that may not align with cross-reactivity NDF-RT Many class definitions, all constrained to enumerations, which differ -> New classes based on cross-reactivity

Quality assurance Caveat: this work is not to be used to map clinical records, and should have no direct effect on any patient. Its sole purpose is to identify frequently used concepts to facilitate information capture. Issues Dirty data: ignore ambiguous items and items below threshold Inconsistent reporting of negatives: partition negative analysis Duplication: assume duplicates are randomly distributed Divergent population sizes: compare contributor profiles to identify specific issues, but do not weight incidence Process For each string, if count(maps) > 1 and all maps agree, status = OK If count(maps) < 2, acquire more maps If maps disagree, review

QA Example 5 maps for term RxNorm for this map Don’t use salt Typo Agreement on map UMLS for some maps

System Options System Substance Class Mixture Realm License SNOMED CT Yes Only for products International Required RxNorm No US Free UNII NDF-RT Possible ATC INN* TBD *No identified source for INN