Dr. Kristofer Smith's recent visit to a patient at her Queens home was not your typical doctor's appointment -- a 15-minute visit with a harried-looking physician in a cold exam room. It was part of a three-year program the North Shore-Long Island Jewish Health System is participating in under the federal Affordable Care Act to provide home-based health care to about 350 elderly. The hope is to take care of their medical problems before those spiral out of control, reducing expensive visits to the emergency room and time in the hospital. The program is just one experiment to keep people out of the hospital. The Affordable Care Act and private health insurers are moving toward a system in which doctors and hospitals will be rewarded for keeping patients healthy, instead of being reimbursed for each service -- called fee-for-service -- used to treat them when they are sick.