  Diagnosis of a clinical condition is a challenging task, which often requires
significant medical investigation. Previous work related to diagnostic
inferencing problems mostly consider multivariate observational data (e.g.
physiological signals, lab tests etc.). In contrast, we explore the problem
using free-text medical notes recorded in an electronic health record (EHR).
Complex tasks like these can benefit from structured knowledge bases, but those
are not scalable. We instead exploit raw text from Wikipedia as a knowledge
source. Memory networks have been demonstrated to be effective in tasks which
require comprehension of free-form text. They use the final iteration of the
learned representation to predict probable classes. We introduce condensed
memory neural networks (C-MemNNs), a novel model with iterative condensation of
memory representations that preserves the hierarchy of features in the memory.
Experiments on the MIMIC-III dataset show that the proposed model outperforms
other variants of memory networks to predict the most probable diagnoses given
a complex clinical scenario.
