Updating the OMERACT filter: implications for patient-reported outcomes.

Objective: At a previous Outcome Measures in Rheumatology (OMERACT) meeting, participants reflected on the underlying methods of patient-reported outcome (PRO) instrument development. The participants requested proposals for more explicit instrument development protocols that would contribute to an enhanced version of the "Truth" statement in the OMERACT Filter, a widely used guide for outcome validation. In the present OMERACT session, we explored to what extent these new Filter 2.