WEDNESDAY, Feb. 19, 2020 (HealthDay News) -- There may be something about a patient's age of 80 that makes doctors alter their heart attack treatment decisions -- consciously or not, new research suggests.

In a study of U.S. heart attack patients, researchers found that just one month in age made a difference in whether doctors performed bypass surgery -- one of the treatments for the artery blockages that cause heart attacks.

Among patients who had turned 80 within the past two weeks, just over 5% received bypass surgery. In contrast, the rate was 7% among patients who were about to turn 80 in the next couple weeks.

Researchers said the finding points to a "left-digit bias" -- where doctors may be more concerned about surgery complications just because a patient's age starts with an 8 rather than a 7.

"These patients were really all the same age, with just a few weeks separating them," said lead researcher Dr. Anupam Jena, an associate professor at Harvard Medical School. "But this study suggests doctors were seeing them differently."

Coronary bypass surgery involves taking a healthy blood vessel from a patient's leg, arm or chest, and using it to reroute blood flow around a blockage in a heart artery.

The surgery is not the only option for heart attack patients. Doctors often perform an alternative called angioplasty, where a catheter is threaded into a blocked artery and a stent is inserted to prop the vessel open.

In general, patients in their 80s have more health problems and tend to be frailer than younger patients -- and they are more likely to have bypass surgery complications, such as new blood clots, infections and heart arrhythmias.

So it's perfectly reasonable, Jena said, for doctors to have that in mind when there's a decision between surgery or a less invasive option like angioplasty.

But it's "unlikely" that poorer health could explain the lower rate of bypass among 80-year-olds in this study, he added.

The findings, published Feb. 20 in the New England Journal of Medicine, are based on Medicare data from 2006 through 2012. Jena's team focused on more than 4,400 heart attack patients who were admitted to the hospital during the two weeks before their 80th birthday, and another roughly 5,000 patients who were admitted within two weeks of turning 80.

Overall, the "older" group was less likely to receive bypass surgery -- even though they were no different from the "younger" group in terms of chronic health conditions and disabilities, Jena said.

In a sense, such left-digit bias is not surprising: It's a common phenomenon of the human mind, Jena pointed out.

"It's why you go to the store and things cost $9.99 instead of $10," he said. "The mind sees the 9 as cheaper."

And while grocery shopping is not the same as medical decision-making, Jena said, the findings suggest that a similar bias can creep into doctors' thinking.

Dr. Patrick Coll is medical director for senior health at UConn Health, in Farmington, Conn. He agreed that the findings likely point to a bias in doctors' views.

But age alone should not keep patients from a particular treatment, said Coll, who is also a member of the American Geriatrics Society's Board of Directors.

"We have a saying that once you've seen one 80-year-old patient, you've seen one 80-year-old patient," said Coll, who wasn't part of the study.

Age does make a difference in whether a given treatment is a good option, according to Coll. "But age is not the primary determinant," he said. "It's the 'medical baggage' that can go along with age."

Coll said it's probably wise for doctors to think about their own biases, and how they might be affecting patient care.

According to Jena, left-digit bias may be "both conscious and unconscious" -- in that doctors know that elderly patients have relatively higher complication risks, but may not fully realize they're using such a mental "short-cut" in presenting treatment options to a patient.

As for patients, simple awareness is important, Jena said. "They should know that the biases doctors have may affect the treatment options they offer," he said.

More information

The U.S. National Heart, Lung, and Blood Institute has more on heart surgery.