Effect of Bowel Preparation Quality On Screening Interval After a Normal Screening Colonoscopy Mark Zeglis, Matthew Chang, Hyungjin Myra Kim, Latoya Kuhn, Grace Elta, Philip Schoenfeld Background: Suboptimal bowel cleansing has been associated with lower polyp detection rates. When bowel cleansing is suboptimal, endoscopists may deviate from published guidelines about intervals between screening colonoscopies. Purpose: To assess the association between bowel cleansing quality and recommended interval between colonoscopies among patients with a normal screening colonoscopy. Methods: Single center, retrospective chart review of openaccess colonoscopies in 50-75 year old average risk individuals referred for colorectal cancer (CRC) screening between 11/04 and 9/05. Incomplete procedures, procedures with polypectomy or biopsies, and procedure reports without recommendations about repeat colonoscopies were excluded. 85% had a standard Fleet’s phospho-soda bowel preparation. Abstracted data: age, gender, FOBTstatus, fellow participation, name of attending endoscopist (n Z 29), recommended interval between colonoscopies. Quality of bowel cleansing was quantified as excellent (O95% of mucosa visualized); good (90-95%); fair (80-90%); or poor (!80%). The likelihood of a 10 year follow-up recommendation was compared across prep quality groups. The impact of bowel cleansing quality on follow-up intervals was assessed with multivariate logistic regression while controlling for age, gender, fellow participation, and FOBT status. Results: 882 subjects met inclusion criteria. Quality of bowel cleansing: ‘‘excellent’’: 35.7%; ‘‘good’’: 40.5%; ‘‘fair’’: 19.4%; and ‘‘poor’’: 4.4%. The likelihood of a 10 year follow-up interval varied significantly (p ! 0.001) across prep groups: ‘‘excellent’’: 89.8%; ‘‘good’’: 77.9%; ‘‘fair’’: 26.3%; and ‘‘poor’’: 5.1%. Multivariate analysis provided the OR of a 10 year interval for each prep quality group compared to ‘‘excellent’’ bowel cleansing: ‘‘good’’: OR Z 0.43 (p Z 0.002); ‘‘fair’’: OR Z 0.03 (p ! 0.001); and ‘‘poor’’: OR Z 0.004 (p ! 0.001). Only 68.9% of total subjects were instructed to repeat a colonoscopy in 10 years. Of subjects instructed to return in ! 10 years, 28% were recalled in 6-9 years, 58% in 5 years, and 14% in 1-4 years. Age, gender, fellow participation, and FOBT status were not independent predictors of a 10 year followup interval. Conclusion: A significant minority (31.1%) of patients with a normal screening colonoscopy were asked to return for repeat colonoscopy in ! 10 years. Suboptimal bowel preparation appears to be the single predictor of this deviation from current guidelines. If confirmed at other sites, these findings suggest that bowel cleansing quality affects the overall cost of CRC screening with colonoscopy and should encourage the development of better bowel preparation regimens.