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. 2015 Aug 20;17(8):e204. doi: 10.2196/jmir.4427

Figure 1.

Figure 1

Example of term expansion for HCUP CCS codes; each code is represented as its set of ICD-9 codes. The ICD-9 code for essential hypertension is expanded using the UMLS Metathesaurus to identify the n terms mapped to that concept. Each of the n terms (eg, “essential hypertension nos,” red) is used as a seed query to our custom lexicon to identify additional concepts and their terms. Here, “essential hypertension nos” maps to the concept hypertensive disease, and its additional m-1 terms (green) are used in combination with the n seed terms to identify searches corresponding to the HCUP CCS codes for hypertension.