L-Tryptophan and Eosinophilia-Myalgia Syndrome ("EMS")

National epidemic of new syndrome in 1989 quickly traced to a commercial product. Case study addresses surveillance, bias, criteria for causation.

Objectives:

• Discuss issues related to rapid establishment of national surveillance for a newly recognized and little understood disorder
• Discuss development of case definitions
• Describe the elements of design and the advantages and disadvantages of case‑control versus cohort studies
• Discuss some of the biases that might have affected these studies
• Calculate and interpret a relative risk, odds ratio, and attributable risk percent
• List and evaluate the criteria for causation