Adenoma Detection Rates in Screening versus Surveillance Colonoscopies: Data from the New Hampshire Colonoscopy Registry: ACG Colorectal Cancer Prevention Award

Abstract

Purpose: The adenoma detection rate (ADR) is a key indicator for measuring colonoscopy quality in screening examinations. Benchmarks of 25% and 15% have been recommended for men and women respectively (age 50 and older) who are screened. Although ADR was initially intended to measure quality for first time screening exams, surveillance exams are often included when ADR is calculated. It is unclear whether this expanded application of ADR is appropriate as there is little comparison data. While it is reasonable to assume that there may be a higher ADR (% of exams in which one or more adenomas are found) among the higher risk surveillance patients, the rate for this group may, in fact, be lower due to the increased frequency of colonoscopy. Our goal was to investigate these rates using the population-based database, the New Hampshire Colonoscopy Registry (NHCR), to determine whether or not ADR is similar for screening and surveillance groups. Methods: Of the 17,428 exams from consenting NHCR participants in 16 facilities, we included screening or surveillance exams (April 2009 to March 2011). Indications included personal history of polyps or colorectal cancer (CRC), Patients with a first degree relative (FDR) with CRC or polyps were included but patients with familial syndromes or IBD were excluded. Since CRC screening begins at age 50, we excluded patients < 50 yrs. Diagnostic exams, exams with fair, poor or unknown bowel prep or exams where an indication of incomplete end of procedure status was noted were excluded. We compared ADR between screening and surveillance exams for the entire sample, for men and women, and by age groups (50-65 and 65-85). ADR's were compared using a Chi-square test. Results: There were 8,300 exams for analysis. The ADR for surveillance exams was 29%; this was higher than the ADR for screening exams, which was 22% (p<0.0001) when examining the total population. When examined by gender, the ADR for surveillance exams was higher than screening exams for men (35% vs. 28%; respectively, p<0.0001) and women (22% vs. 18%; respectively, p<0.001). The age subgroup analysis demonstrated this relationship for the younger (50-65) but not the older group (65-85). These data are shown in the Table.Table: [1973] Adenoma detection rates for screening versus surveillance examsConclusion: In our statewide population, there was a statistically significant higher ADR for surveillance exams than for screening exams. This relationship was seen for both men and women, particularly in the 50-65 year age group. Thus, it may not be appropriate to measure ADR in surveillance exams, using benchmarks established for screening. In addition, a new benchmark for surveillance exams may be needed for appropriate quality assessments of colonoscopy.