How variability in the institutional review board review process affects minimal-risk multisite health services research.

Background: The Department of Health and Human Services recently called for public comment on human subjects research protections.

Objective: To assess variability in reviews across institutional review boards (IRBs) for a multisite, minimal-risk trial of financial incentives for evidence-based hypertension care and to quantify the effect of review determinations on site participation, budget, and timeline.

Design: A natural experiment occurring from multiple IRBs reviewing the same protocol for a multicenter trial (May 2005 to October 2007).