The COGS Study explores the mechanisms by which aging increases the risk of postoperative delirium and cognitive decline in order to improve the cognitive outcomes of older surgical patients
COGS Study
Our research was born from three basic facts: one, older adults are the largest population of surgical patients. Despite representing just 15% of the population, older adults constitute over 50% of all surgical admission in the U.S. Two, older adults are also more likely to have some sort of cognitive impairment. And three, despite these facts, the brain is the only major organ system not routinely assessed preoperatively.
Age-related cognitive impairment, which is common among seniors living independently in the community, is a strong and independent predictor of mortality and surgical complications. For example, a person with cognitive impairment is at higher risk for delirium, functional decline, hospital readmission, and discharge to some place other than home after a medical or surgical hospitalization. Why, then, aren’t we routinely screening for it before major operations? Seniors are nearly three times more likely to have surgery than a middle-aged individual and it is apparent that we need to know more about how to identify and care for these patients. Hence, the Cognition and Outcomes of Geriatric Surgery Study (COGS Study) began. Born in 2015, COGS incorporates several studies under one umbrella, all devoted to understanding the impact of preoperative cognition on postoperative outcomes.
Older adults constitute over 50% of all surgical admission in the U.S.
The elderly in the United States amount to 15% of the total popultion.
Seniors are nearly three times more likely to have surgery than a middle-aged individual.
Several events got us here. First, we are basic neuroscientists and have long been researching the impact of general anesthesia and surgery on learning and memory in rats and mice. One of the things we noticed in that work is how much variability exists among older rodents in learning and memory functions. Second, we watched our parents and family members deal with serious illness and surgery and saw first-hand how cognitive impairment before or after a procedure complicates the struggle for a full recovery. Then, in 2012, we were invited to write an editorial about a paper that showed, using formal and time consuming cognitive testing, that many older surgical patients had cognitive impairment before surgery. This was news because brain function was not then, and still is not today, formally evaluated preoperatively.
Put simply, if you don’t look for it, you won’t find it. If impairment is present but undiagnosed, doctors cannot adjust their treatment accordingly. We highlighted this omission in the editorial and made a “call for action” for routine preoperative cognitive screening. When a year later no one had taken the bait, we decided to do it ourselves.
Our education in clinical research and cognitive screening began after the 2012 paper. This was new territory for us and it was slow going at the start. What test? What patients? What about false positives? Fortunately, we knew experts to call on. Because of our interest in aging, we interacted regularly with geriatricians. As basic neuroscientists, we collaborated with a world-class expert in the neurology of memory disorders who introduced us to experts in geriatric psychiatry and epidemiology. Everyone was interested and enthusiastic. Likewise, our orthopedic and neurosurgical colleagues doing total joint replacements and/or spine surgeries, some of the most common procedures in older patients, were very supportive and eager to participate. We met with, talked to, and learned from this outstanding multidisciplinary team.
Thanks to them and a group of talented and dedicated research assistants, we have now cognitively screened more than a thousand [1,000] older surgical patients preoperatively. We have introduced routine cognitive screening into the pre-admission test center at our institution, and found that 20-40% of older patients having elective surgery probably have cognitive impairment at baseline that would go unnoticed without structured cognitive screening. Most importantly, we discovered that doing poorly on a preoperative cognitive screening test predicts increased risk for postoperative complications and/or a suboptimal outcome. Thus, preoperative cognitive screening is a simple but high-impact way to inform and enhance clinical decision-making and possibly improve surgical outcomes.
Moving Forward
We still have much to learn, but our team is devoted to the cause and to doing better for our older surgical patients. In the clinic, we are exploring the mechanisms by which poor cognition leads to poor postoperative outcomes and looking for ways to personalize and improve care for older patients at risk. Meanwhile, in the laboratory we are investigating how general anesthesia and surgery alter the brain to the point of producing long-lasting memory impairment. Perhaps most importantly, we are working to educate older patients and their families, as well as the anesthesiology and surgical communities, about how important preoperative brain function and health are to a good surgical outcome.
Meet the Team
Interested in learning more about our research or participating in a clinical study? Please get in touch with the COGS Study using the form below.
Harvard Medical School
75 Francis Street
Boston, MA
