First a.m. colonoscopy yielded more polyps

Colonoscopies performed first thing in the morning yielded significantly more polyps and more histologically confirmed polyps than did those performed later in the day, according to a study presented at the annual Digestive Disease Week.

In medicine it’s well-known that errors accumulate, particularly in anesthesia and surgery, as the day progresses, the University of California, Los Angeles. “Any surgeon will tell you that he’d rather be the firs case of the day if he has to go under the knife.” The study they presented appears to extend these results to both surveillance and screening colonoscopy.

They performed a retrospective analysis of 500 consecutive patients seen at the West Los Angeles Veterans Administration Medical Center in 2006-2007. At that institution, colonoscopy cases begin at 7:45 a.m. and typically end at 1 p.m. The investigators divide that time into five segments that they analyzed separately.

Colonoscopists found a mean of 2.6 polyps per patient seen before 8:30 a.m., 2.1 polyps between 10 a.m. and 11:30 a.m., and 1.2 polyps after 1 p.m. On average, the first colonoscopy of the day found 20% more polyps than did those performed later in the day, a statistically significant difference. The trend line was also statistically significant.

The investigators noticed a similar pattern when they restricted their analysis to histologically confirmed polyps. The colonoscopists found a mean of 2.1 hyperplastic polyps during the first case of the day, 1.6 in cases between 10 a.m. and 11:30 a.m., and 1.1 in cases after 1 p.m. That trend line also was statistically significant.

The first case of the day remained a significant independent predictor of polyp yield even after the investigators controlled for a host of potential confounders in a multivariate analysis (P=.004). They controlled for patient-level factors such as age and body mass index, provider-level factors such as which individual colonoscopist performed the procedure and whether he or she was a fellow, and procedure-level factors such as the quality of the bowel prep and the withdrawal time.

Of those factors, the only other independent predictor of polyp yield was whether or not a fellow was participating in the procedure. Fellow participation was a strong predictor of higher yield (P=.00001). It was suggested that one reason the presence of fellows may have improved yield is that there were “two [sets of] eyes on the screen instead of one.”

The study generated some critical comment during the question-and-answer period. Although no one intentionally assigned a specific type of case to a specific time period, one audience member said that there might be some undetected bias in appointment times, with a certain type of patient choosing earlier or later appointments.

Another physician noted that some colonoscopy centers perform many more procedures per day than does the West Los Angeles VA Medical Center and suggested that the result might have been different if the study had been conducted elsewhere.

Another audience member commented that they worry that when the New York Times or the Wall Street Journal gets hold of this paper and publishes it widely, they’re going to begin to have great difficulties scheduling patients in the afternoon.

They agreed that the study should be repeated elsewhere before anyone takes it too seriously. And whether it’s the New York Times or anyone else, they have no idea that this impacts advanced adenomatous cancer in terms of survival.

But if the results are generalizable and colonoscopists are simply more vigilant earlier in the day, they suggested that clinicians look to other industries, such as air-traffic control and long-distance trucking that depend on constant vigilance. In those industries, strategies such as split-shift scheduling, visible prompts, and frequent reminders to be vigilant have proved helpful.