Figure 1.

A high-level diagram of the system (i.e., NLP-PAC). There are two components in NLP-PAC: the text processing component extracts concepts in PAC delineated in Table 1 from medical records, and the asthma status ascertainment component classifies asthma status at a patient level using pattern-based rules, assertion status (e.g., nonnegated, associated with patient), and section constraints (e.g., diagnosis). EMR = electronic medical records; NLP = natural language processing; PAC = predetermined asthma criteria.