The incident user design in comparative effectiveness research

Eric S. Johnson, Barbara A. Bartman, Becky A. Briesacher, Neil S. Fleming, Tobias Gerhard, Cynthia J. Kornegay, Parivash Nourjah, Brian Sauer, Glen T. Schumock, Art Sedrakyan, Til Stürmer, Suzanne L. West, Sebastian Schneeweiss

Research output: Contribution to journalArticlepeer-review

150 Scopus citations


Comparative effectiveness research includes cohort studies and registries of interventions. When investigators design such studies, how important is it to follow patients from the day they initiated treatment with the study interventions? Our article considers this question and related issues to start a dialogue on the value of the incident user design in comparative effectiveness research. By incident user design, we mean a study that sets the cohort's inception date according to patients' new use of an intervention. In contrast, most epidemiologic studies enroll patients who were currently or recently using an intervention when follow-up began. We take the incident user design as a reasonable default strategy because it reduces biases that can impact non-randomized studies, especially when investigators use healthcare databases. We review case studies where investigators have explored the consequences of designing a cohort study by restricting to incident users, but most of the discussion has been informed by expert opinion, not by systematic evidence. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.

Original languageEnglish (US)
Pages (from-to)1-6
Number of pages6
JournalPharmacoepidemiology and drug safety
Issue number1
StatePublished - Jan 2013

All Science Journal Classification (ASJC) codes

  • Epidemiology
  • Pharmacology (medical)


  • Comparative effectiveness
  • Inception cohort
  • Incident interventions
  • Pharmacoepidemiology
  • Study design


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