ACR-FDA Summit Focuses on Study Design, Safety Considerations

The timing of study measurements is also important. Study outcomes may not occur immediately after drug initiation, and some drugs used to treat rheumatic conditions may have latent effects after discontinuation. It can be useful to define a latent period after drug initiation in which outcomes are not counted, as well as an extension period after discontinuation—perhaps 6 to 12 months depending on the study and treatment—to account for latent effects, Dr. Bradley said.

Other challenges include identifying true new users of a drug, confounding by indication and choosing an active comparator for studies in the real world.

Vanessa Caceres is a medical writer in Bradenton, Fla.