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 specifi c 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.