Doctors can expect to receive about $42 a month for managing the care of a Medicare patient. Care management services can be provided only if patients agree in writing. Patients will pay about 20 percent of the $42 fee, the same proportion as for many other doctor services.

Medicare wants to require doctors managing care to use electronic health records so they can more easily exchange information with other health care providers treating a patient.

Kenneth E. Thorpe, chairman of the department of health policy at Emory University, said, “The rising prevalence of chronic conditions, including diabetes and obesity, accounts for much of the growth in Medicare spending in recent years.”

The new care management services can be provided not only by doctors but also by nurse practitioners, physician assistants and certain other health professionals. Medicare officials said they expected doctors and other providers to focus on sicker patients with four or more chronic conditions.

“This is time-consuming and challenging work,” said Dr. Matthew J. Press, an assistant professor of health care policy at Weill Cornell Medical College in New York. In a recent article in The New England Journal of Medicine, he described his experience coordinating care for a 70-year-old man with bile duct cancer in the liver.

Over 80 days, Dr. Press said, 10 doctors helped care for the man, who had five procedures and 11 office visits before a surgeon removed his tumor. Dr. Press, the patient’s primary care doctor, communicated 40 times with the other clinicians and 12 times with the patient or his wife.

Poor coordination can cause medical errors — if, for example, doctors are unaware of abnormal laboratory test results or drugs that a patient is taking. “Patients can be harmed when the many moving parts of their care are out of sync,” Dr. Press said.