The review, of 13 clinical trials, found that when doctors were given training to hone their people skills, patients typically fared better in their efforts to lose weight, lower their blood pressure or manage pain.
Experts said the findings, reported online April 9 in the journal PLOS One, show that the doctor-patient relationship can have an impact on people's health.
The effects in these studies were small, but still "impressive," said Alan Christensen, a professor of psychology at the University of Iowa.
Christensen, who was not involved in the research, studies the issue of health care provider-patient relationships. He pointed out that many of the training programs in the studies included in the new review focused on fairly "general" skills -- such as maintaining eye contact with patients, and listening without interrupting.
So it's encouraging to see that these training programs translate into specific health benefits at all, according to Christensen.
"It's important to be able to demonstrate that clinicians can learn to change how they interact with patients, and that it affects health outcomes," he said.
Dr. Helen Riess, the senior researcher on the new study, agreed. "I think that intuitively, people think that if you have an open, caring relationship with your provider, that's beneficial."
But to really know if there are objective health effects, clinical trials are key, said Riess, who directs the empathy and relational science program at Massachusetts General Hospital in Boston.
For its review, she said her team chose only rigorous clinical trials that measured "hard outcomes," such as blood pressure changes -- as opposed to subjective experiences like patient satisfaction.
The researchers ended up with 13 clinical trials from around the world. In each, health providers -- most often doctors -- were randomly assigned to either stick with their usual care or have some kind of training on patient interaction. Some focused on building "warmth" and empathy, Riess said, while others taught providers specific techniques, like "motivational interviewing."
In most of the trials, though not all, patients seemed to benefit. Obese and diabetic patients tended to lose more weight, arthritis patients reported less pain, and people with high blood pressure did a better job of lowering their numbers.
Those effects were "modest" overall, Riess and colleagues found. But the magnitude of the benefit was similar to what's been seen in studies testing low-dose aspirin or cholesterol-lowering statins for preventing heart attack, according to the new research.
"That's important because aspirin and statins are widely prescribed, and everyone agrees they should be used to reduce the risk of heart attack," Riess said.
It's not clear, she added, exactly why the trials in this review found benefits: Is it the improved empathy, or the motivational interview technique, for example?
And of course, individuals differ in what they consider a "good" relationship with their doctor, Christensen noted.
"People clearly differ in how much information they want," he said. "Some people want greater self-management, and see it as having more control. Some people see it as a burden. Some people like being asked about their personal life, beyond their health condition. Some don't."
But the bottom line, Christensen and Riess both said, is that the provider-patient relationship matters.
"Patients need to understand that it's OK to look for a doctor who meets your preferences and expectations," Christensen said.
Or, since finding a new doctor can be tough, Riess suggested talking to your current doctor.
"If you're unhappy, there are polite ways to speak up," she said. "Patients should feel empowered to say, 'I didn't understand that language you used. Can you explain it in laymen's terms?' You can tell (your doctor) if you feel rushed or anxious."
And don't worry about offending your doctor, Christensen advised. He said most doctors do care, and say they try to "tailor" how they communicate to individual patients.
But if patients don't speak up, Riess noted, a doctor might not realize there's a problem.