Polyp and adenoma detection rates were highest when the colonoscopy withdrawal time was 9 minutes long, near the upper limit of the recommended 6 to 10 minutes withdrawal time, researchers found.
For each minute of normal withdrawal time above 6 minutes, incident rate ratios for detection of adenomas or clinically significant serrated polyps increased by 50% (incident rate ratio 1.50, 95% CI 1.21-1.85) and 77% (incident RR 1.77, 95% CI 1.15-2.72), respectively, with a leveling benefit at 9 minutes, according to , of the Norris Cotton Cancer Center in Lebanon, N.H., and colleagues.
"Our investigation demonstrates a statistically significant correlation between longer normal withdrawal time and higher polyp detection rates, adenoma detection rates, and serrated polyp detection rates ... and provides strong evidence to support a 9-minute median normal withdrawal time as a quality standard," they wrote online in the .
In November 2013, the CDC reported that colon cancer screening rates rose from 2002 to 2010, but that roughly a third of adult patients were not up to date with tests for malignancy.
The authors reviewed data of 7,996 colonoscopies from 7,972 patients, which were performed by 42 endoscopists from 2009 to 2011. The data were recorded in the New Hampshire Colonoscopy Registry, a statewide, population-based registry from ambulatory surgery centers, hospital-based practices, academic, and community centers "with participating endoscopists from a variety of specialties."
They noted that New Hampshire has one of the highest colorectal cancer screening rates in the U.S. of roughly 76%.
Outcomes of interest included polyp detection rates, adenoma detection rates, and serrated polyp detection rates out of the total number of colonoscopies performed. Practitioners recorded withdrawal time in 1-minute increments from less than 2 minutes to greater than 10 minutes. Data on how time was measured not collected.
Patient covariates included age, sex, race, body mass index, and prior colonoscopy, while healthcare professional characteristics included age, sex, specialty (gastroenterologist, general or colorectal surgeon), and volume.
Most patients were 50 to 69 years old (81%), white (92%), women (52%), and were overweight or obese (67%). Polyps, adenomas, and clinically significant serrated polyps were present in 48%, 27%, and 8.3% of colonoscopies, respectively.
Normal withdrawal time ranged from 3 minutes to more than 10 minutes, with a common median time of 8 minutes, followed by a normal withdrawal time of 6 or fewer minutes in 24% of screens. Detection rates for adenomas and polyps were highest in procedures that withdrew at 9 minutes, while serrated polyp detection was greatest at 8 minutes and remained high at 9 minutes (10.2% versus 9.5%).
The study was limited by minute-long intervals of withdrawal time, as well as a lack of specific recorded time for procedures that took longer than 10 minutes. They also did not know reasons for prolonged procedures. The results may not be generalizable racially due to the high makeup of white patients in the study.
Disclosures
The study was supported by the National Cancer Institute.
The authors declared that they had no conflicts of interest.
Primary Source
The American Journal of Gastroenterology
Butterly L, et al "Serrated and adenomatous polyp detection increases with longer withdrawal time: results from the New Hampshire colonoscopy registry" Am J Gastroenterol 2014; DOI: 10.1038/ajg.2013.442.