Explainable machine learning to identify risk factors for unplanned hospital readmissions in Nova Scotian hospitals

A report from the Canadian Institute for Health Information found unplanned hospital readmissions (UHR) common, costly, and potentially avoidable, estimating a $1.8 billion cost to the Canadian healthcare system associated with inpatient readmissions within 30 days of discharge for the studied period (11 months). The first step towards addressing this costly problem is enabling early detection of patients at risk through detecting UHR risk factors.

We utilized Machine Learning and explainability tools to examine risk factors for UHR within 30 days of discharge, utilizing data from Nova Scotian (Canada) healthcare institutions (2015-2022). To the best of our knowledge, our research constitutes the most comprehensive study on UHR risk factors for the province.

We found that predicting UHR solely from healthcare data has limitations, as discharge information often falls short of accurately predicting readmission occurrences. However, despite this inherent limitation, integrating explainability tools offers insights into the underlying factors contributing to readmission risk, empowering medical personnel with information to improve patient care and outcomes. As part of this work, we identify and report risk factors for UHR and build a guideline to support medical personnel's decision-making regarding targeted post-discharge follow-ups. We found that conditions such as heart failure and Chronic Obstructive Pulmonary Disease (COPD) are associated with a higher likelihood of readmission. Patients admitted for procedures related to childbirth have a lower probability of readmission. We studied the impact of the admission type, patient characteristics, and patient stay characteristics on UHR. For example, we found that new and elective admission patients are less likely to be readmitted, while patients who received a transfusion are more likely to be readmitted.

We validated the risk factors and the guidelines using real-world data. Our results suggested that our proposal correctly identifies risk factors and effectively produces valuable guidelines for medical personnel. The guideline evaluation suggests we can screen half the patients while capturing more than 72% of the readmission episodes. Our study contributes insights into the challenge of identifying risk factors for UHR while providing a practical guideline for healthcare professionals to identify factors influencing patient readmission, particularly within Nova Scotia.