A physician’s adenoma detection rate – the proportion of screening colonoscopies he or she performs that detect at least one histologically confirmed colorectal adenoma or adenocarcinoma – strongly correlates with patients’ risk of developing interval cancer, according to a report published online April 2 in the New England Journal of Medicine.
Adenoma detection rates vary widely among physicians, and this statistic is used as a quality benchmark even though its usefulness in predicting outcomes "has not been well validated" until now, said Douglas A. Corley, M.D., Ph.D., of the division of research at Kaiser Permanente in Oakland, Calif., and his associates.
Dr. Douglas Corley
They used information from Kaiser’s database of approximately 3.3 million annual visits to 17 northern California medical centers to identify 314,872 colonoscopies performed on patients aged 50 years and older by 136 gastroenterologists over a 12-year period. A total of 712 interval cancers developed in the study participants during 6 months to 10 years of follow-up (927,523 person-years of follow up), including 147 fatal cases. The median interval between colonoscopy and colorectal cancer diagnosis was 39 months.
Adenoma detection rates varied greatly among the gastroenterologists, ranging from 7.4% to 52.5%. A physician’s adenoma detection rate showed a strong, linear, dose-dependent correlation with his or her patients’ cancer risk. For patients of physicians with adenoma detection rates in the highest quintile (33.51%-52.51%), compared with those of physicians with adenoma detection rates in the lowest quintile (7.35%-19.05%), the risk of developing an interval cancer was 0.52; every 1% increase in the rate predicted a 3% reduction in cancer risk, the investigators said (N. Engl. J. Med. 2014;370:1298-306 [doi:10.1056/NEJMoa1309086]).
This suggests that physicians who increase their adenoma detection rate from less than 19% (the lowest quintile) to more than 34% (the highest quintile) "might prevent 1 additional interval cancer over the next 10 years for every 213 colonoscopies," Dr. Corley and his associates said.
The findings were similar in analyses restricted to advanced-stage and fatal interval cancers. "For patients of physicians with rates in the highest quintile of adenoma detection rates, as compared with patients of physicians with rates in the lowest quintile, the risk of receiving a diagnosis of advanced-stage interval colorectal cancer was reduced by 57% and the risk of a fatal interval colorectal cancer was reduced by 62%. Each 1% increase in the adenoma detection rate was associated with a 5% decrease in the risk of a fatal interval colorectal cancer," they wrote.
"These findings support the validity of the adenoma detection rate as a quality measure of physicians’ performance of colonoscopy in community practice," the investigators added.
This study was supported by the Kaiser Permanente Community Benefit program and the National Cancer Institute. Dr. Corley and his associates reported no financial conflicts of interest.