(Reuters Health) - Screening older surgery patients for cognitive impairment can catch undiagnosed problems that raise risk for complications, researchers say.

Among 211 patients over age 65 having elective orthopedic surgeries such as hip or knee replacement, pre-operative screening found that about one quarter had likely cognitive impairment such as undiagnosed dementia.

These patients were at increased risk of post-operative delirium, longer hospital stays and not being discharged to home, the study team reports in Anesthesiology.

“We really don’t do enough in the preoperative space to look at impairment and frailty in geriatric patients. We may test mobility, but we need more subtle measures of the brain,” said lead author Dr. Deborah Culley of Harvard Medical School in Boston.

About one of every three surgical procedures in the U.S. involves a patient aged 65 or older, the study authors write. Although most surgical centers assess an older patient’s physical condition before surgery, some are now beginning to test brain function as well, especially in patients without a history of dementia, they note.

“When you talk with a patient before surgery, you can notice an impairment in this stressful environment,” Culley told Reuters Health in a phone interview. “It’s essentially a cognitive stress test.”

Culley and her colleagues screened patients at Brigham and Women’s Hospital in Boston who were scheduled for an elective hip or knee replacement. They used the Mini-Cog test, which involves a three-item memory recall test. The research team defined patients with low scores of 2 or less on the test’s five-point scale as likely cognitively impaired.

Once the surgery was over, they looked at in-hospital medical complications, hospital length-of-stay and discharge information, such as discharge to a place other than the patient’s home, as well as 30-day emergency room visits and death.

Fifty of the 211 patients, or 24 percent, scored 2 or lower on the pre-surgery test. These patients were more likely than those with higher scores to be older, have a lower education level and poorer physical functioning. These patients were also 37 percent more likely to have a longer hospital stay after the surgery, four times as likely to be discharged to a place other than their home and four and a half times as likely to develop post-operative delirium and confusion, the study found.

“What’s novel about this is we’re looking at the brain now. Since the 1970s we’ve looked at organs such as the heart, lungs and kidney to understand surgery risk, but now we’re looking at the most vital organ,” said Dr. Thomas Robinson of the University of Colorado Anschutz Medical Campus in Denver, who wasn’t involved in the study.

“Anesthesiologists are particularly paying attention because they give so much sedation in the operating room,” he told Reuters Health by phone. “Medications have been closely associated with mental function after surgery.”

Future studies should look at different cognitive screening instruments, as well as different types of surgeries and different risk factors that make delirium worse in older patients, the study authors write. Culley said she is now following spine surgery patients, who tend to have higher rates of delirium after surgery.

“I’d like to find an online cognitive screening tool that patients can take before they get to surgery so we have an idea of what’s going on before we’ve scheduled appointments,” she added.

Robinson, who is studying postsurgical pain and ways to block it to reduce delirium, said he sees future studies measuring brain markers for cognitive impairment and identifying high-risk patients sooner to create personalized postoperative recovery instructions.

“It sounds simple, but hospitals still don’t do this well,” he said. “We have guidelines for physical therapy after operation, but we should also implement cognitive therapy.”

“With this screening tool, a daughter of an older patient with some cognitive impairment, for example, could know the likelihood of her parent going home and the higher risk of developing delirium,” Culley said. “A change could be as simple as making sure she’s in the recovery room after surgery to reorient the patient better.”

If patients or family members believe impaired cognition or dementia could be a factor in surgery, they should ask their doctors and surgeons for a plan that will improve postsurgical care, according to the American Society of Anesthesiologists Brain Health Initiative.

SOURCE: bit.ly/2A0sC5S Anesthesiology, online November 1, 2017.