Loss to follow-up of enrolled patients (a.k.a. attrition) is a major threat to study validity and power. Minimizing attrition can be challenging even under ideal research conditions, including the presence of adequate funding, experienced study personnel, and a refined research infrastructure. Emergency care research is shifting toward enrollment through multisite networks, but there have been limited descriptions of approaches to minimize attrition for these multicenter emergency care studies. This concept paper describes a stepwise approach to minimize attrition, using a case example of a multisite emergency department prospective cohort of over 3,000 patients that has achieved a 30-day direct phone follow-up attrition rate of <3%. The seven areas of approach to minimize attrition in this study focused on patient selection, baseline contact data collection, patient incentives, patient tracking, central phone banks, local enrollment site assistance, and continuous performance monitoring. Appropriate study design, including consideration of these methods to reduce attrition, will be time well spent and may improve study validity
