ADR Works in FIT-Positive Populations: Target ADR Must Be Substantially Higher Than Primary Screening ADR
Douglas K. Rex, MD, MASGE, reviewing Wisse PHA, et al. Ann Intern Med 2022 Sep 27.
It is well known that the prevalence of adenomas is higher in patients with a positive result from a stool test, including both the fecal immunochemical test (FIT) and multi-target DNA-FIT. In calculating adenoma detection rate (ADR) for primary screening in the U.S., it is recommended that these patients be excluded from the ADR calculation.
ADR is well established as a predictor of postcolonoscopy colorectal cancer (PCCRC) in general colonoscopy populations but not in FIT-positive populations.
In this study from the Netherlands, 116,360 colonoscopies were performed by 362 endoscopists. The cutoff for a positive FIT was 47 µg Hb/g feces.
The median ADR was 67%, with a range of 40% to 82%, and there were 209 interval PCCRCs. For each 1% increase in ADR, there was a 5% drop in the hazard ratio (HR) for interval PCCRC. After 5 years, the interval PCCRC rate was approximately 2 per 1000 colonoscopies for an ADR of 70%, but the interval PCCRC rates were 2.5, 3.5, and >4.5 for ADRs of 65%, 60%, and 55%, respectively. Other measures such as mean adenomas per colonoscopy, mean adenomas per positive procedure, and advanced adenoma detection rate were also associated with PCCRC but did not outperform ADR. The PCCRC risk was higher for colonoscopists in nonacademic hospitals (HR, 3.74) and nonacademic endoscopy centers (HR, 3.87).
COMMENTThis is an important study because it shows that the ADR concept works in FIT-positive populations. The U.S. Multi-Society Task Force on Colorectal Cancer recommended that ADR targets in FIT-positive populations in the U.S. should be 15% higher than those for primary screening populations, or 35% for women and 45% for male patients. These targets seem too low in the context of the current study, but remember that the cutoff for a positive FIT in the United States is 20 µg Hb/g feces; therefore, the prevalence of adenomas in FIT-positive patients in the U.S. is lower.
The use of variable cutoffs in hemoglobin levels in the stool in various countries poses a challenge to establishing uniform international target ADRs for FIT-positive populations. These data make it clear that FIT-positive and Cologuard-positive patients should continue to be excluded from screening-ADR calculations in the U.S. or subject to separate ADR measurements.
Note to readers: At the time we reviewed this paper, its publisher noted that it was not in final form and that subsequent changes might be made.
CITATION(S)
Wisse PHA, Erler NS, de Boer SY, et al. Adenoma detection rate and risk for interval postcolonoscopy colorectal cancer in fecal immunochemical test-based screening: a population-based cohort study. Ann Intern Med 2022 Sep 27. (Epub ahead of print) (https://doi.org/10.7326/m22-0301)
