Annotating a corpus of clinical text records for learning to recognize symptoms automatically

We report on a research effort to create a corpus of clinical free text records enriched with annotation for symptoms of a particular disease (ovarian cancer). We describe the original data, the annotation procedure and the resulting corpus. The data (approximately 192K words) was annotated by three clinicians and a procedure was devised to resolve disagreements. We are using the corpus to investigate the amount of symptom-related information in clinical records that is not coded, and to develop techniques for recognizing these symptoms automatically in unseen text.