As many as 25% of screening colonoscopies are unnecessary, study finds

Screening colonoscopies in the US declined considerably in 2020 due to Covid-19. The fact that many people at high risk of colon cancer missed this screening is concerning, but it’s not all bad news. Reduction in colonoscopies across the board likely reduced low-value screenings in patients for which screening isn’t recommended, saving patients from overtreatment and other side effects, and saving the health system money. 

We don’t screen every person for every cancer, because the likelihood that young adults have cancer is very low, which makes it more likely they will be harmed by screening than helped. However, in very old age, cancer screening also becomes less beneficial because people are less likely to live long enough to experience benefits from screening, and they are more susceptible to harmful complications of testing and treatment. That’s why the US Preventive Services Task Force recommends screening for colon cancer only from age 45 to 75.

However, many people are screened for cancer even though they are unlikely to benefit. Nursing homes often screen very old people for cancer, even though they are likely to be harmed by surgery or treatment if cancer was found. In one 2014 study, among older patients with very high mortality risk, 40% were screened for colorectal cancer. In another large survey, more than half of people over the recommended screening age reported being screened for colorectal cancer.

How often do we give patients colonoscopies who are too young, too old, or had another screening too recently– and what is the impact on our health system? In the first systematic review of screening colonoscopy overuse, researchers Joseph Fraiman, Shannon Brownlee, Michael A. Stoto, Kenneth W. Lin, and Alison N. Huffstetler take a look at previously published research on the topic to provide an estimate.

They examined six studies which included about 250,000 screening colonoscopies. Overall, the rate of overuse among these studies ranged from 17% to 25.7%. With 6.3 million screening colonoscopies performed in the US each year (before Covid), at least one million–and as many as 1.6 million– are unnecessary. This means many people are at unnecessary risk of harm from potential colonoscopy complications such as bleeding, perforated bowels, and even death. Very old patients are at increased risk of serious side effects (and are among the least likely to benefit from screening colonoscopies). The authors plan to follow up this study with a systematic review of harms from colonoscopies, to estimate how many severe side effects can be attributed to colonoscopy overuse.

Not only does colonoscopy overuse put patients potentially in harm’s way, it also costs the health system $3 billion each year, Fraiman et al. calculate. Although screening colonoscopies are supposed to be covered as preventive care under most insurance, patients can still bear significant out of pocket costs for hospital facility fees and out-of-network charges.

By pausing elective procedures and screenings, Covid-19 offers health systems a chance to evaluate and stop potential overuse. As health systems open back up and preventive colonoscopies are resumed, “special attention should be paid to colonoscopies non-adherent to the guidelines, to avoid the unnecessary risk of COVID transmission in addition to the previously identified risks of colonoscopy,” the authors write.