title: Evaluation of RxNorm for Representing Ambulatory Prescriptions.
abstract: OBJECTIVE
  We evaluated the RxNorm standardized drug nomenclature for representing ambulatory e-prescriptions.
  
  
  METHODS
  Using a sample of 19743 primary care e-prescriptions, we estimated the coverage rate of RxNorm for representing clinical drugs, measured the 6-month replacement rate for RxNorm concepts, assessed the consistency of two independent concept mappings, and investigated inconsistent mappings.
  
  
  RESULTS
  RxNorm contained concepts for nearly all prescriptions in the sample (99.995%). Of 1419 concepts used, 8.1% were replaced between April and October 2009. Independent mappings produced different concepts for 676 e-prescriptions (3.4%), but most differences would have low clinical significance. Most mismatches were related to the use of extended-release form concepts with no duration specified, inhalers vs. their contents, and clinically inert salts.
  
  
  CONCLUSIONS
  RxNorm provides concepts covering nearly all ambulatory e-prescriptions in this setting. Independent mappings were relatively consistent. Improvements could be made by enabling selection of the most-specific concepts when broader prescribable concepts exist.
authors.affiliation: RAND Corporation, Santa Monica, CA;
authors.forename: Sean M
authors.initials: SM
authors.lastname: O'Neill
authors.forename: Douglas S
authors.initials: DS
authors.lastname: Bell
mesh_terms: D006801:Humans; D062245:RxNorm; D018875:Vocabulary, Controlled