A Keyword-Enhanced Approach to Handle Class Imbalance in Clinical Text Classification

Authors:

Abstract
Recent applications ofdeep learning have shown promising results for classifying unstructured text in the healthcare domain. However, the reliability of models in production settings has been hindered by imbalanced data sets in which a small subset of the classes dominate. In the absence of adequate training data, rare classes necessitate additional model constraints for robust performance. Here, we present a strategy for incorporating short sequences of text (i.e. keywords) into training to boost model accuracy on rare classes. In our approach, we assemble a set of keywords, including short phrases, associated with each class. The keywords are then used as additional data during each batch of model training, resulting in a training loss that has contributions from both raw data and keywords. We evaluate our approach on classification of cancer pathology reports, which shows a substantial increase in model performance for rare classes. Furthermore, we analyze the impact of keywords on model output probabilities for bigrams, providing a straightforward method to identify model difficulties for limited training data.
Funding Information
  • Joint Design of Advanced Computing Solutions for Cancer
  • DOE
  • NCI
  • National Institutes of Health
  • DOE
  • Argonne National Laboratory (DE-AC02-06-CH11357)
  • Lawrence Livermore National Laboratory (DE-AC52-07NA27344)
  • Los Alamos National Laboratory (DE-AC5206NA25396)
  • Oak Ridge National Laboratory (DE-AC05-00OR22725)
  • NCI SEER (HHSN261201800013I)
  • CDC National Program of Cancer Registries (U58DP00003907)
  • Commonwealth of Kentucky
  • NCI
  • SEER Program (HHSN261201800007I)
  • NPCR (NU58DP006332-02-00)
  • State of Louisiana
  • NCI
  • SEER Program (HHSN261201300021I)
  • NPCR (NU58DP006279-02-00)
  • State of New Jersey Department of Education
  • Rutgers Cancer Institute of New Jersey
  • NCI's SEER Program (HHSN261201800016I)
  • NPCR (NU58DP0063200)
  • University of Utah
  • Huntsman Cancer Foundation
  • National Cancer Institute's Surveillance (HHSN261201800014I, HHSN26100001)
  • Epidemiology and End Results (SEER) Program
  • National Cancer Institute's SEER Program (HHSN261291800004I)
  • Fred Hutchinson Cancer Center

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