Recruiting eligible patients for clinical trials is crucial for reliably answering specific questions about medical interventions and evaluation. However, clinical trial recruitment is a bottleneck in clinical research and drug development. Our goal is to provide an approach towards automating this manual and time-consuming patient recruitment task using natural language processing and machine learning techniques. Specifically, our approach extracts key information from series of narrative clinical documents in patient's records and collates helpful evidence to make decisions on eligibility of patients according to certain inclusion and exclusion criteria. Challenges in applying narrative clinical documents such as differences in reporting styles and sub-languages are addressed by enriching them with knowledge from domain ontologies in the form of semantic vector representations. We show that a machine learning model based on Multi-Layer Perceptron (MLP) is more effective for the task than five other neural networks and four conventional machine learning models. Our approach achieves overall micro-F1-Score of 84% for 13 different eligibility criteria. Our experiments also indicate that semantically enriched documents are more effective than using original documents for cohort selection. Our system provides an end-to-end machine learning-based solution that achieves comparable results with the state-of-the-art which relies on hand-crafted rules or data-centric engineered features.
Keywords: Artificial neural networks; Clinical document classification; Clinical trials; Cohort selection; Deep learning; Natural language processing.
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