Methods for Handling Inter-Hospital Transfer in acute Myocardial Infarction Research

Context Patients are frequently transferred during their care for acute myocardial infarction. The clinical risks and benefits associated with inter-hospital transfer have not been fully evaluated. Objective To compare and contrast the analytic methods used to handle transferred patients in previous acute myocardial infarction research. Design Systematic review of acute myocardial infarction literature over the past 10 years. Main Outcomes Benefits and risks of various methods used for handling transferred patients in acute myocardial infarction research. Results Seven major methods for dealing with inter-hospital transfer emerged: 1) Count each hospitalization as a separate event. 2) Delete transferred patients from analysis. 3) Link the data from different hospitals and produce a record of the “episode” of acute myocardial infarction. 4) Analyze data on transferred patients the same as on non-transferred patients. 5) Transfer patients are the specific population of interest. 6) Diagnosis, treatment, outcomes are attributed to the index hospital. 7) Control for transfer in logistic regression modeling. Several studies included a combination of these methods. Conclusion Inter-hospital transfer in the care of acute MI is common and increasing. From a clinical standpoint, determining the patient most likely to benefit from inter-hospital transfer will help guide clinicians faced with this difficult decision. From a health services standpoint it is essential to understand the implications of using a particular method for handling transfer patients, the impact on data collection, the data lost, the appropriate analyses, and the generalizability of findings.