Improved Patient Classification with Hierarchical Language Model Pretraining over Clinical Notes
Jonas Kemp, Alvin Rajkomar, Andrew M. Dai
Abstract: Clinical notes in electronic health records contain highly heterogeneous writing styles, including non-standard terminology or abbreviations. Using these notes in predictive modeling has traditionally required preprocessing (e.g. taking frequent terms or topic modeling) that removes much of the richness of the source data. We propose a pretrained hierarchical recurrent neural network model that parses minimally processed clinical notes in an intuitive fashion, and show that it improves performance for discharge diagnosis classification tasks on the Medical Information Mart for Intensive Care III (MIMIC-III) dataset, compared to models that conduct no pretraining or that treat the notes as an unordered collection of terms. We also apply an attribution technique to examples to identify the words that the model uses to make its prediction, and show the importance of the words’ nearby context.