WEDNESDAY, Sept. 26, 2012 (HealthDay News) -- Doctors who counsel patients not to drive or to drive with extra caution for medical reasons may help save the life of their patient as well as others on the road, a large new study finds.
The downside of this advice is that doctors run the risk of ruining the relationship with their patient when they suggest limiting their independence, the researchers say.
"Medical warnings to unfit drivers lead to a 40 to 50 percent reduction in the risk of a serious motor vehicle crash," said lead researcher Dr. Donald Redelmeier, from the department of medicine at the University of Toronto.
The decrease in risk, however, did not bring it down to the population norm, Redelmeier said. Most of the decreased risk was among elderly women living in rural areas, he added.
These findings may be due to the fact that while people were driving less, licenses were suspended in only 20 percent to 30 percent of cases, Redelmeier explained.
People warned about driving include those diagnosed with or taking medications for sleep apnea, high blood pressure or Parkinson's disease. Redelmeier noted that warnings were never given due to a patient's age, but rather because of a medical condition.
These conditions can include dizzy spells, stroke, epilepsy, Alzheimer's disease, alcoholism, advanced diabetes or schizophrenia, Redelmeier noted.
The warnings, however, increased patients' depression and significantly affected the doctor-patient relationship, he said. "This is why clinical judgment is needed so an intervention isn't carried to excess," Redelmeier said.
"This can be painful news to hear," he said. "It can be unpleasant news for a lot of patients to hear, but that's what good medicine is often about, unfortunately."
In most cases patients can still drive, Redelmeier pointed out. "It's a matter of driving more carefully," he said.
The report was published Sept. 27 in the New England Journal of Medicine.
For the study, the researchers identified patients whose doctor had warned them that they were potentially unfit to drive.
Between April 2006 and December 2009, more than 100,000 patients had received warnings from more than 6,000 doctors, the researchers found.
In the three years before the warnings, 1,430 car crashes occurred in which the patient was driving. In the year after a doctor's warning, crashes dropped to 273 -- a 45 percent reduction in crashes per 1,000 patients warned, the researchers reported.
The reduction in crashes was seen across the board among all patients regardless of age or the reason for the warning.
Warnings, however, were associated with more visits to the emergency room for depression and a drop in return visits to the doctor who gave the warning, the researchers added.
In Canada, doctors are paid when they warn patients about not driving and report it to the government. In the United States, however, doctors aren't paid for this advice and reporting requirements vary by state with most states not having any reporting requirements, Redelmeier noted.
In May, the American Medical Association launched a course to help doctors figure out when and how to tell a patient to limit driving or not drive.
"The AMA encourages physicians to make driver safety a routine part of their geriatric medical services," the association said in a statement.
But that's easier said than done, said Dr. Bradley Flansbaum, an internist at Lenox Hill Hospital in New York City, who was not involved with the study. Telling a patient to limit his or her driving is a thorny problem, he noted.
"When you talk about people's independence -- take away someone's keys and their life changes," Flansbaum said. "If it worked and the patient got off the road that would be hunky-dory, but that's not the way the world works," he added.
For a doctor it's not an easy problem to deal with, he explained. Flansbaum said if he knew a patient had had an accident, then he would advise the patient about driving. But without an accident, it is a gray zone and he would be less likely to offer driving advice.
Part of the problem, he suggested, is lack of support from state or federal government -- for instance, consistent regulations on reporting unfit drivers, or having drivers with medical conditions pass a test. Such national policies might help by taking the sole responsibility out of the doctor's hands, he said.
"It's a judgment call," Flansbaum added. "That's why it's so hard."
To learn more about medically impaired driving, visit the Oregon Department of Motor Vehicles.