Serrated Polyp Detection a Good Indicator of Colonoscopy QualityJuly 22, 2022
While the adenoma detection rate (ADR) is a well-established quality indicator for colonoscopy, the proximal serrated polyp detection rate (PSPDR) should be used as a complementary tool, according to a Dutch population-based study.
Among over 200,000 colonoscopies performed by 441 endoscopists, each percentage point increase in the PSPDR was associated with a 7% lower risk of interval post-colonoscopy colorectal cancer (HR 0.93, 95% CI 0.90-0.95, P<0.0001), reported Evelien Dekker, MD, of Amsterdam University Medical Center in the Netherlands, and colleagues.
The median PSPDR was 11.9% and the median ADR was 66.3%. The correlation between the PSPDR and ADR was moderate (r=0.59, P<0.0001), so “we should not assume that endoscopists with high ADR also have a high PSPDR, and thus advocates adoption of PSPDR as a separate quality indicator,” the authors noted in Lancet Gastroenterology and Hepatology.
During a median follow-up of 33 months, 305 interval post-colonoscopy colorectal cancers were detected. Compared with endoscopists with a PSPDR and ADR both above the median, the HR of interval post-colonoscopy colorectal cancer was:
- 1.79 (95% CI 1.22-2.63) for endoscopists with a low PSPDR and a high ADR
- 1.97 (95% CI 1.19-3.24) for endoscopists with a high PSPDR and a low ADR
- 2.55 (95% CI 1.89-3.45) for endoscopists with a low PSPDR and a low ADR
“The benefit of adding PSPDR to existing quality indicators is shown by the markedly increased risk of interval post-colonoscopy colorectal cancer in endoscopists with high ADR but low PSPDR, compared with endoscopists with a high ADR and high PSPDR,” Dekker and team observed. “Hence, we propose that the PSPDR should not be considered as a surrogate parameter for ADR or vice versa, but as an additional quality indicator, to be used alongside the ADR.”
The ADR is currently the main tool for measuring and benchmarking an endoscopist’s performance in detecting premalignant lesions and preventing interval post-colonoscopy colorectal cancers. However, the authors pointed out that ADR does not include serrated polyps, “even though these lesions appear to cause a considerable proportion of interval post-colonoscopy colorectal cancers.”
The PSPDR has several advantages over other possible quality indicators, such as the sessile serrated lesion (SSL) detection rate or the serrated polyp detection rate (SPDR), noted co-author Joep IJspeert, MD, also of Amsterdam University Medical Center, in an audio recording accompanying the study.
He noted that it is difficult to differentiate between hyperplastic polyps and SSLs, “even for expert pathologists.” When looking at the SSL detection rate, IJspeert said the question becomes whether “you’re looking at a good pathologist or a good endoscopist. And that’s a problem.”
He also pointed out that many patients have distal hyperplastic polyps. “So, if you’re going to resect one of these innocent distal hyperplastic polyps, you will have a positive colonoscopy in the case of the serrated polyp detection rate,” he explained. “That’s why we chose the proximal serrated polyp detection rate — leaving out the distal hyperplastic polyps and also leaving out the histopathology differentiation between hyperplastic polyps and SSL.”
In an accompanying commentary, Joaquín Cubiella, MD, PhD, of Complexo Hospitalario Universitario de Ourense in Spain, noted that the study took place in a high-quality setting, with endoscopists and pathologists specifically trained in the detection and diagnosis of serrated lesions. Thus, while the results of the study are impressive, he said, “the value of the PSPDR as a quality indicator needs to be externally validated in different settings before it is widely recommended for use.”
If the results are replicated in these different settings, “PSPDR and ADR should be systematically measured to detect endoscopists with lower performance and apply training programs to improve their detection rate,” he added.
For this study, Dekker and colleagues used data from the Dutch colorectal cancer screening program and the Netherlands Cancer Registry. Patients ages 55 to 76 were eligible for inclusion if they had a positive fecal immunochemical test and underwent a colonoscopy from January 2014 through December 2020.
The PSPDR was defined as the proportion of colonoscopies in which at least one serrated polyp proximal to the descending colon was detected, confirmed by histopathology, while the ADR was defined as the proportion of all colonoscopies in which at least one conventional adenoma was detected, confirmed by histopathology.
During the study period, 329,104 colonoscopies were performed, of which 277,555 were included in the PSPDR calculations (mean age 68, 58% men). These colonoscopies were performed by 441 endoscopists, with a median of 542 colonoscopies per endoscopist.
The association between PSPDR and interval post-colonoscopy colorectal cancer was significant for both women (HR 0.92, 95% CI 0.88-0.95) and men (HR 0.94, 95% CI 0.90-0.97).
Limitations to the study included the potential for confounding factors, as well as the short follow-up period (median 36 months), which could have led to underestimation of the incidence of interval post-colonoscopy colorectal cancers.
Dekker reported consulting fees from Fujifilm, Olympus, GI Supply, CPP-FAP, PAION, and Ambu; serving as a speaker for Olympus, GI Supply, Norgine, Ipsen, PAION, and Fujifilm; receiving payments as a member of the supervisory board of the eNose company; and loaning endoscopic equipment for research studies from Fujifilm.
A co-author reported relationships with the Netherlands Institute of Public Health and the Environment/Screening Organization, TKI/Health Holland, Dutch Gastroenterology Association, ZonMw, Sysmex, Sentinel, Boston Scientific, and Norgine.
Cubiella had no disclosures.