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Study supports use of adenoma detection rate as quality indicator for colonoscopy screening

Wednesday, May 19 2010 | Comments

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What's This? New data suggest that the endoscopist's adenoma detection rate is an independent predictor of a patient's colorectal cancer (CRC) risk following a screening colonoscopy, supporting the use of this variable in quality-assessment and quality-improvement programs for CRC screening.

The study evaluated the association between 2 quality indicators for colonoscopy--adenoma detection rate and cecal intubation rate--and the risk of interval CRC, defined as cases of colorectal adenocarcinoma diagnosed between the time of a screening colonoscopy and a scheduled surveillance colonoscopy. Cases of interval cancer were included only if the involved bowel segment had been visualized in the screening colonoscopy (ie, the cancer was presumed to have developed from lesions missed during screening). 

The endoscopist's adenoma detection rate was defined as the proportion of subjects screened by the endoscopist in whom >=1 adenomatous lesion had been identified. The cecal intubation rate was defined as the proportion of complete examinations (passage of the colonoscope tip to a point proximal to the ileocecal valve, with visualization of the entire cecum), adjusted for incomplete exams resulting from poor bowel preparation or stricture caused by a tumor.

The study included data for 45,026 subjects who received a screening colonoscopy, following adequate bowel preparation, from any of 186 endoscopists who performed >=30 screening examinations during the study period. A total of 42 cases of interval CRC were identified during 188,788 person-years of follow-up.

In a multivariate model that included endoscopist-related variables (adenoma detection rate, cecal intubation rate, sex, age, and specialty) and patient-related variables (age, sex, family history of CRC), the endoscopist's adenoma detection rate was significantly associated with the risk of interval CRC (P=.008).

Relative to the patients screened by an endoscopist with an adenoma detection rate of >=20.0%, those who were screened by an endoscopist with a lower detection rate were significantly more likely to develop interval CRC. Specifically, the hazard ratio for interval CRC was 10.94 (95% CI, 1.37-87.01) with a detection rate of <11.0%, 10.75 (95% CI, 1.36-85.06) with a detection rate ranging from 11.0% to 14.9%, and 12.50 (95% CI, 1.51-103.43) with a detection rate ranging from 15.0% to 19.9%.

The only other variable in the model that significantly predicted interval CRC was the patient's age. The study investigators noted that patients aged 60 years or older had a particularly high risk of interval CRC.

They added that the rate of cecal intubation, the other quality indicator assessed in this analysis, was not significantly associated with interval CRC (P=.5).

"[O]ur findings indicate that the endoscopist's rate of adenoma detection is an independent predictor of the risk of interval cancer after screening endoscopy with clearing of all visualized lesions in the large bowel," the authors concluded. "Our findings support the primary role of this measurement in continuous quality-improvement programs for CRC screening." (Kaminski MF, et al. N Engl J Med 2010;362:1795-1803.)

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