Double trouble: a propensity-matched cohort study evaluating the associations between duplicate medical records and patient outcomes

INTRODUCTION: Duplicate medical records occur when a single patient is assigned multiple medical record numbers within an instance of an electronic health record, potentially associated with fragmented care and adverse outcomes. Despite these concerns, limited research has evaluated the correlation between duplicate charts and patient outcomes. OBJECTIVE: To examine the association between duplicate charts and patient outcomes, including hospital length of stay, 30-day readmission, rapid response events, intensive care unit (ICU) level of care, and in-hospital mortality. METHODS: This retrospective cohort study analysed hospitalised patients aged 18-89 across 12 hospitals within a large multi-region health system from July 1, 2022 to June 30, 2023. Propensity score matching balanced covariates between patients with and without duplicate charts. Primary outcomes included in-hospital mortality, rapid response events, ICU level of care, hospital length of stay, 30-day readmission and 30-day emergency department visits. Standardised mean differences assessed group balance, and multivariable logistic or linear regression models, adjusted for discharge service and disposition, examined the relationship between patients with and without duplicate records and the selected outcomes. RESULTS: After matching, 1698 patients with duplicate charts were compared with 4388 without. Patients with duplicate records had significantly higher odds of adverse outcomes, including 30-day readmission (OR=1.3, 95% CI 1.1 to 1.5, p=0.0122), ICU level of care (OR=3.5, 95% CI 3.1 to 4.0, p