Dr. Patrick Quinlan will step down Sept. 1 as chief executive officer of Ochsner Health System, handing control of the region's largest health-care provider to his longtime second-in-command, President and Chief Operating Officer Warner Thomas. Quinlan, who has led Ochsner since 2001, will remain in the system as a governing board member and as director of a new enterprise: the Ochsner Center for Wellness and Health Policy. The leadership transition has been formally in the works for more than a year, according to the two executives and Ochsner board president Jimmy Maurin. Quinlan will keep his vote on the Ochsner governing board in one of the seats reserved for physicians.