Nearly 600 doctors were surveyed for the study to determine how aggressively they treat their patients and whether non-medical issues have influenced their decisions to order invasive heart tests.
Most said they weren't swayed by such things as financial gain or a patient's expectations. But about 24 percent of the doctors said they had recommended the test in the previous year because they were worried about malpractice lawsuits. About 27 percent said they did it because they thought their colleagues would do the test.
Doctors who treated their patients aggressively were more likely to be influenced by malpractice worries or peer pressure than those who weren't as aggressive, the study determined.
The research was done to see whether doctors' attitudes and practices might be contributing to the wide differences in health care use and spending across the country.
“We have known for a long time that where you live has an influence on what kind of health care you get and how much health care you get,” said Lee Lucas, lead author of the study and associate director of the Center for Outcomes Research and Evaluation at Maine Medical Center.
Some of the reasons are known: differences in disease rates, patient preferences and the availability of medical services or hospital beds. And more care isn't necessarily better care, Lucas noted.
For the study, the doctors were asked to recommend tests and treatment for three hypothetical heart patients. Their answers were used to score them on how aggressively they tend to treat patients.
Using Medicare records, the researchers found that doctors with higher scores were more likely to be in the areas with higher spending overall or higher rates for a heart test, although the differences were small.
The doctors were also asked whether other issues had led them to recommend the heart test - called a cardiac catheterization - during which a thin tube is threaded to the heart to check how well it is working and to look for disease.
The researchers suggest that targeting malpractice concerns could help reduce the regional differences.
“We need a way for docs to be less afraid of not ordering a test,” said Lucas.
Medical malpractice was part of the health care reform debate, but didn't make it into the recently approved legislation. The new law does include pilot programs for states to explore alternatives to lawsuits.
The study was released Tuesday by the journal Circulation: Cardiovascular Quality and Outcomes.
The results support moving toward more integrated health care, and away from fee-for-service payments, and working on malpractice reforms, said Kenneth Thorpe, a professor of health policy at Emory University in Atlanta.
Lucas said patients can help by not pressuring their doctors to do tests.
“If he says you don't need it, let it go,” she said.
