The number of adenomas per colonoscopy (APC) is inversely correlated with post-colonoscopy colorectal cancer (PCCRC), which supports the use of APC as a new quality control measure, according to the researchers.
Data from 138 endoscopists showed that patients screened by doctors with higher APCs had significantly lower PCCRC rates and an APC of 0.6 offered more protection than either an APC of 0.4 or an adenoma detection rate (ADR) of 25%, reported first author Joseph C. Anderson, MD, of White River Junction VA Medical Center, Hanover, NH, and colleagues.
“Unfortunately, APC has never been validated as a measure of quality by showing a decrease in PCCRC on examinations of endoscopists at higher rates,” Anderson said at the American College of Gastroenterology’s annual meeting.
To do this, Anderson and colleagues reviewed data from the New Hampshire Colonoscopy Registry (NHCR), including 9,023 screening colonoscopies with a follow-up event 6-60 months after the initial exam. The procedures were performed by 138 endoscopists in New Hampshire, Vermont, Massachusetts, and Maine.
Three quality measures were analyzed for associations with PCCRC: an APC of 0.4, an APC of 0.6 and an ADR of 25%. Hazard ratios were calculated for all PCCRCs as well as for PCCRCs diagnosed at first follow-up. The rates were reported for two periods: 6-36 months and 6-60 months.
From 6 to 60 months, 82 cases of PCCRC were diagnosed, of which 50 were diagnosed between 6 and 36 months.
For both periods, all three quality measures were significantly associated with a reduction in the PCCRC. However, the higher APC of 0.6 provided better protection and reduced all PCCRCs by 71% and 61% over the shorter and longer periods, respectively. In comparison, the lower APC of 0.4 lowered rates by 63% and 53%, respectively, while the ADR benchmark lowered rates by 62% and 42%, respectively.
These trends were maintained for PCCRCs diagnosed at the first follow-up event. An APC of 0.6 was associated with corresponding reductions of 79% and 65% for the shorter and longer periods, compared with 64% and 57% for the lower APC and 67% and 49% for ADRs.
An additional analysis clarified the relationship between the APC level and the likelihood of developing PCCRC. In terms of absolute risk, patients examined by an endoscopist with an APC greater than 0.6 had a 0.5% chance of developing a PCCRC after 6 to 36 months, compared with 0.7% at an APC of 0.4-0.6 and 2.1% for an APC of less than 0.4 (P = 0.0001). This pattern persisted for 60 months, during which time an APC greater than 0.6 was associated with an absolute risk for PCCRC of 0.4% compared to 0.7% for an APC of 0.4-0, 6 and 1.6% for an APC less than 0.4 (P = 0.0001).
“Our novel data supports the use of APC as a measure of quality by showing a reduction in the risk of PCCRC when examining endoscopists with higher APCs,” concluded Anderson, noting that an APC of 0.6 appears to offer more protection than an APC of 0.4. “I have a feeling that … APC can be accepted as a quality measure now that we have validated it because it can differentiate endoscopists in terms of their adenoma detection abilities.”
According to Lawrence Hookey, MD, of Queen’s University in Kingston, Ontario, “It’s an important study that is likely to add where we are going.”
Lawrence, chairman of the division and medical director of the endoscopy units at Kingston General and Hotel Dieu Hospitals, said APC could overcome the main concern with ADRs – that endoscopists who find an adenoma may not be motivated to see as many as possible Looking for.
“The problem with ADR in general is that if you find a polyp, and if ADR is the value you live by, you don’t have to find any other polyps, and that obviously isn’t doing the patient a favor, necessarily,” Hookey said in an interview. “It brings them back to surveillance sooner, but it doesn’t help remove the rest of the polyps that they haven’t been looking so hard for.”
APC mitigates this problem, he said, because it determines “whether you really work things out and get rid of that many”. [polyps] as possible.”
Hookey said that APC was “probably the best” quality control measure on the horizon, and he suggested that more work is needed to determine the optimal benchmark number, which ideally should be explored by larger studies.
“I just want to see it in larger groups,” he said.
Investigators and Hookey did not report any conflicts of interest.
This article originally appeared on MDedge.com, part of the Medscape Professional Network.
