After months of negotiating that left thousands of patients in insurance limbo, PA-based Crozer-Keystone Health System and Keystone Mercy Health Plan signed a contract hours before the old one was set to lapse. Keystone Mercy had recently mailed letters to 5,000 members in Delaware County, PA, assigning them to new primary-care doctors willing to accept the region's largest Medicaid managed-care plan. Thousands more already had chosen new doctors outside the Crozer system. The new agreement, which runs until the end of 2011, took effect May 1. Details were not disclosed.