LTR-ICD: A Learning-to-Rank Approach for Automatic ICD Coding
Mohammad Mansoori, Amira Soliman, Farzaneh Etminani
TL;DR
This paper addresses the need to preserve ICD code order in automatic coding. It introduces LTR-ICD, a two-module, shared-encoder framework that jointly learns to classify ICD codes and generate an ordered code sequence, optimized via a ranking mechanism. Evaluated on MIMIC-III, the model achieves superior ranking of high-priority codes and better macro and micro F1 metrics compared with state-of-the-art classifiers, demonstrating practical improvements for clinical coding and billing workflows. Limitations include reliance on ICD-9 and a single-hospital dataset, with future work expected to extend to ICD-10/ICD-11, multilingual data, and enhanced interpretability.
Abstract
Clinical notes contain unstructured text provided by clinicians during patient encounters. These notes are usually accompanied by a sequence of diagnostic codes following the International Classification of Diseases (ICD). Correctly assigning and ordering ICD codes are essential for medical diagnosis and reimbursement. However, automating this task remains challenging. State-of-the-art methods treated this problem as a classification task, leading to ignoring the order of ICD codes that is essential for different purposes. In this work, as a first attempt, we approach this task from a retrieval system perspective to consider the order of codes, thus formulating this problem as a classification and ranking task. Our results and analysis show that the proposed framework has a superior ability to identify high-priority codes compared to other methods. For instance, our model accuracy in correctly ranking primary diagnosis codes is 47%, compared to 20% for the state-of-the-art classifier. Additionally, in terms of classification metrics, the proposed model achieves a micro- and macro-F1 scores of 0.6065 and 0.2904, respectively, surpassing the previous best model with scores of 0.597 and 0.2660.
