Research fundamentals: follow-up of subjects in clinical trials: addressing subject attrition

Acad Emerg Med. 2004 Aug;11(8):859-66. doi: 10.1111/j.1553-2712.2004.tb00769.x.


Many published clinical trials have less than adequate follow-up. When conducting a clinical trial, researchers attempt to minimize data loss; however, some data may not be collected, particularly when subjects are lost to follow-up. Careful planning of research protocols, including comprehensive initial data collection, identification of locators, flexible scheduling, systematic subject tracking, monitoring subject loss, and systematically approaching problem cases can ensure high follow-up rates. This article presents a compendium of techniques and procedures that researchers can use to enhance follow-up and address attrition in their studies. Finally, this article outlines statistical techniques that can be used to address the effects of missing data, particularly when patients are lost to follow-up.

Publication types

  • Review

MeSH terms

  • Appointments and Schedules
  • Clinical Trials as Topic / methods*
  • Clinical Trials as Topic / standards
  • Data Interpretation, Statistical
  • Emergency Medicine / methods*
  • Follow-Up Studies*
  • Humans
  • Interviews as Topic / methods
  • Professional-Patient Relations
  • Refusal to Participate*
  • Reproducibility of Results
  • Research Subjects*