Data Leakage Due to Care Provided Outside of the Study Electronic Health Record System: Potential Biases and Solutions

Information bias due to electronic health record (EHR) system data discontinuity, i.e., data leakage due to care provided outside of study EHR, can lead to misclassification of essential variables in comparative effectiveness research. We have developed an analytical approach to reduce such biases and tested it in a few empirical examples in routine-care databases.