The ngram chief complaint classifier: A novel method of automatically creating chief complaint classifiers based on international classification of diseases groupings

Introduction: The ngram classifier is created by using text fragments to measure associations between chief complaints (CC) and a syndromic grouping of ICD-9-CM codes. Objectives: For gastrointestinal (GI) syndrome to determine: (1) ngram CC classifier sensitivity/specificity. (2) Daily volumes for ngram CC and ICD-9-CM classifiers. Methods: Design: Retrospective cohort. Setting: 19 Emergency Departments. Participants: Consecutive visits (1/1/2000–12/31/2005). Protocol: (1) Used an existing ICD-9-CM filter for “lower GI” to create the ngram CC classifier from a training set and then measured sensitivity/specificity in a test set using an ICD-9-CM classifier as criterion. (2) Compare daily volumes based on ICD-9-CM with that predicted by the ngram classifier. Results: For a specificity of 0.96, sensitivity was 0.70. The daily volume correlation for ngram vs. ICD-9-CM was R = 0.92. Conclusion: The ngram CC classifier performed similarly to manually developed CC classifiers and has advantages of rapid automated creation and updating, and may be used independent of language or dialect.