Health plan quality-of-care information is undermined by voluntary reporting.

Background: Most health services in the United States are delivered by managed care organizations (MCOs). Publicly available, plan-specific performance information is required to adequately assess healthcare quality provided. Using women's health indicators, we compared performance results for MCOs and evaluated whether those MCOs that publicly report quality-of-care (QOC) results demonstrate better QOC than those plans that restrict public access to data.