Dr. Sunita Sah practiced general medicine for several years in the United Kingdom’s National Health Service. When she came to the United States, she noticed something strange.

The U.K. guidelines for tests such as mammograms and colon cancer screenings drastically differed from those in the U.S. – even though they were based on the same medical evidence.

“Having colonoscopy at the age of 50 – that struck me as rather odd when I moved to the U.S., because you don’t really hear about people having colonoscopies as a screening procedure in the U.K.,” said Sah. “It’s much less invasive to test for blood in the stool. It’s also less costly and doesn’t have the risks of undertaking a colonoscopy.”

Now an assistant professor of management and organizations at Cornell, Sah and Ismail Jatoi of the University of Texas Health, San Antonio, say the treatment guidelines recommended by medical specialist organizations are more likely to call for greater use of health care services and exacerbate overdiagnosis, overtreatment and spiraling health care costs. Their commentary, “Clinical Practice Guidelines and the Overuse of Health Care Services: Need for Reform,” appeared March 18 in the Canadian Medical Association Journal.

The implications are significant, she said, because guidelines are supposed to provide standard evidence-based treatment practices for all doctors.

“The recommendations put out by specialty organizations – like the American College of Cardiology or the American College of Radiology – show specialty bias in recommending more aggressive and/or more frequent screening procedures,” said Sah, an expert on conflict of interest. “In the U.S. in particular, where the fee-for-service compensation model dominates medicine, which is different from countries like the U.K., you see even more recommendations for greater use of health care services.”

Specialty bias refers to the tendency of physicians to recommend the treatments in which they are trained to deliver. For example, localized prostate cancer can be treated with either surgery or radiation.

“If you go to a surgeon, chances are that they are more likely to recommend that you have surgery; if you go to a radiation oncologist, they are more likely to recommend that you have radiation,” she said. “They each often believe that the treatment that they’re trained in is the better one.”

In the case of screening for colorectal cancer, the American College of Gastroenterology’s panel – all of whom were gastroenterologists – recommended colonoscopy as the best strategy.

But the United States Preventive Task Force, with no gastroenterologists or gastrointestinal surgeons, recommended testing the stool, sigmoidoscopy (an exam of only the lower part of the colon) or colonoscopy as a last resort. Stool testing was also recommended by the European Society of Medical Oncology panel, which consisted of six medical oncologists, no gastroenterologists and one gastrointestinal surgeon. The panel said there was limited evidence that screening colonoscopy is effective.

“Colonoscopies are more invasive than stool testing and come with potentially greater risks and costs for patients – but increased clinical volume and profits for gastroenterologists,” Sah said.

Specialty guidelines are also subject to fee-for-service bias, according to the commentary. Doctors who receive a payment for each treatment may tend to recommend that treatment more often, because they have a financial interest in it.

“The bias is not necessarily malicious or intentional,” Sah said. “In a fee-for-service environment, they may be biased to do more rather than less, so it becomes a habit.”

But more is not necessarily better, she said. “Sometimes the risks of those procedures are just not worth the benefits.”

The authors call for a reduction in conflicts of interest in the fee-for-service model, and more professional diversity in the makeup of the guideline committees. “You need a variety of different voices on those committees,” Sah said.

And patients could ask their doctors which guidelines they follow and why. “Ask them questions,” she said. “Ask your doctor to explain their thought process in recommending the particular guideline and the advantages or disadvantages of one guideline versus another.”