"Doctors make diagnoses," Wennberg said. "If you go to lots of doctors and doctors, they are going to make more diagnoses."
This complicates efforts to measure the quality and effectiveness of care, said Dr. Ashish Jha, an associate professor of health policy at the Harvard School of Public Health.
In an effort to improve health care, there's a growing movement to grade doctors and hospitals on performance, and to attach pay to how well doctors perform.
To make things fair, grading systems usually account for how sick patients are to avoid penalizing doctors who are taking care of a sicker group of people.
But research such as this study shows such methods may be flawed, because those who appear to have more chronic illnesses may not actually be any sicker than those with fewer chronic illnesses, and vice versa, he said.
Put simply: a patient diagnosed with heart disease and diabetes would be sicker than a patient with only one condition, but whether they are diagnosed with both may be more related to where they live and how many doctors they see.
Or, perhaps a patient gets an X-ray and is surprised to learn she has mild lung disease. If she were in another region were lower intensity healthcare, she might never get that X-ray and she'd feel fine and never learn she had lung disease.
But if those doctors in the high-intensity region "get credit" for having a sicker patient due to the chronic disease diagnosis, it may look like they're performing better when they're actually not.
"This is a really important study and a really important finding," Jha said. "If you are a doctor who is very good, but you don't order lots and lots of tests, it might look like your patients are not that sick and therefore your outcomes might look worse. Obviously, the last thing we want to do is
All rights reserved