included data about patient characteristics, endoscopist specialty, facility typeand geographic region. The use of deep sedation was identified by a concurrentclaim for anesthesia services. Using diagnosis codes, we identified theoccurrence within 30 days of the colonoscopy of hospitalizations for splenicrupture or trauma, colonic perforation, and aspiration pneumonia. The outcomeswere compared using univariate analysis and independent predictors ofcomplications were examined in a multivariate logistic model. Results: Weidentified a total of 139,889 diagnostic colonoscopies, including 30,270 withanesthesia services (21.8%). The prevalence of anesthesia increased markedlyfrom 2000 (9.0%) to 2009 (34.8%) and was also much more frequent in theNortheastern US (44.4%) than in other regions (18.4%). Selected post-proceduralcomplications were documented in 194 patients (0.14%) and included aspiration(n�110), perforation (n�78) and splenic injury (n�7). Overall complicationswere more common in cases with anesthesia assistance (0.18%) than others(0.13%) (p�0.03), as was aspiration (0.11% vs. 0.07%, respectively, p�0.05).Frequencies of perforation (0.06% vs. 0.05%, p�0.9) and splenic injury (0.013%vs. 0.003%, p�0.07) were statistically similar. Other predictors of complicationsincluded age � 70, increasing Charlson comorbidity score, and performance in ahospital setting. In multivariate analysis, use of anesthesia services wasassociated with an increased complication risk (odds ratio 1.52, 95% CI1.07-2.14). Conclusions: In this large population-based study, although theabsolute risk of complications was low, the use of anesthesia services forcolonoscopy was associated with a somewhat higher frequency of complicationsthat may reflect the impairment of normal patient responses with deep sedation.This finding represents another potential disadvantage of deep sedation thatshould be considered by patients, endoscopists and third party payers.

657Prone vs Standard, Left-Lateral Decubitus Position Colonoscopyfor Obese Patients: A Randomized, Prospective StudyFatema S. Uddin*, Ramiz Iqbal, William Harford, Kerry B. Dunbar,Byron L. Cryer, Stuart J. Spechler, Linda A. FeaginsDivision of Digestive and Liver Diseases, UT Southwestern/Dallas VAMedical Center, Dallas, TXIntroduction: Obesity is a risk factor for colorectal cancer and, as the incidenceof obesity continues to rise, gastroenterologists are performing colonoscopy onincreasing numbers of obese patients. Colonoscopy can be technicallychallenging in these patients, and it can be especially difficult to reposition asedated, obese patient during the procedure. It has been suggested that theremay be technical advantages to using the prone position for colonoscopy inobese patients and, in our own clinical practice, we have noted good resultswith colonoscopy begun in the prone position for our obese patients. Theseobservations prompted us to conduct a prospective, randomized study of proneposition vs. standard, left lateral decubitus position for colonoscopy. Methods:Patients with a BMI �30kg/m2 who are scheduled for elective colonoscopy inour endoscopy laboratory are invited to participate and to provide written,informed consent. Consenting patients are randomly assigned to havecolonoscopy begun either prone or in the standard, left-lateral decubitusposition. We record the time from rectal insertion to visualization of theappendiceal orifice (cecal intubation time), and whether the endoscopist ordersthe patient to be repositioned in order to complete the procedure. Patients areasked to score their discomfort during the procedure and, 3 days aftercolonoscopy, patients are asked if they would be willing to have repeatcolonoscopies performed in the same position. Patients whose bowelpreparations are rated as inadequate are excluded from the analyses. Results: Atotal of 84 male veterans (mean age 61.6 years) have completed the trial; 41were randomized to the Prone Group and 43 to the Standard Group. The twogroups did not differ significantly in average BMI (36.5kg/m2 prone group,35.7kg/m2 standard group). For all 84 patients, the average cecal intubation timewas 474 seconds. The average cecal intubation time for the Prone Group was392�58 (SEM) seconds, compared to 553�61 for the Standard Group (p�0.017).Patient repositioning during colonoscopy was ordered for 3 patients (7%) in theProne Group, compared to 11 patients (26%) in the Standard Group (p�0.039).Pain during colonoscopy was reported by 61% of patients in the Prone Group,compared to 49% of patients in the Standard Group (p�0.282). Among patientscontacted at 3 days after the procedure (n�78), 100% of patients in the ProneGroup said they would be willing to have repeat colonoscopies performed in thesame position, compared to 92% of patient in the Standard Group (p�0.24).Conclusions: In patients with BMI �30kg/m2, the performance of colonoscopyin the prone position results in significantly shorter cecal intubation times anddecreased need for patient repositioning. Prone positioning is well accepted bypatients and does not significantly increase procedure discomfort.

658Effect of Colonoscopy on Colorectal Cancer Incidence andMortality: An Instrumental Variable AnalysisBinu Jacob, Rahim Moineddin, Rinku Sutradhar, Nancy N. Baxter,David R. Urbach*University Health Network, Toronto, ON, CanadaBackground: Colonoscopy may reduce the incidence and mortality of colorectalcancer (CRC). Using population-based health services information to estimate theeffectiveness of colonoscopy on the risk of CRC incidence and mortality is proneto selection bias, especially since it is difficult to determine whether colonoscopyprocedures are performed for screening or for other purposes. The objective ofthis study was to determine the effect of colonoscopy on CRC incidence andmortality using administrative health data. Methods: We conducted a population-based retrospective cohort study of Ontario residents who were alive and free ofCRC on January 1 2001, who appeared to be at average risk of developing CRC,and who were aged 50-74 during the period 1996-2000 when their exposure tocolonoscopy procedures was ascertained. Subjects were followed up to 7 yearsto identify incident CRC and up to 5 years to ascertain death due to CRC. Eachsubject was linked to a primary care physician (PCP), and each PCP’s use ofcolonoscopy during 1996-2000 was measured. We characterized each PCP’s useof ‘discretionary’ colonoscopy—colonoscopy procedures performed inapparently low-risk screen-eligible persons, which did not result in a subsequentdiagnosis of CRC within 3 years of colonoscopy—and used the PCP rate ofdiscretionary colonoscopy as an instrumental variable. Results: The study cohortcomprised 1, 089,998 persons. A total of 86,837 (7.9%) had undergonecolonoscopy during the period 1996-2000. There were 14,455 (1.3%) new casesof CRC up to 2007 and 2,394 (0.2%) deaths due to CRC up to 2005. Using thePCP rate of discretionary colonoscopy as an instrumental variable, receipt ofcolonoscopy was associated with a 0.60% (95% CI 0.31% to 0.78%) absolutereduction in 7-year colorectal cancer incidence (from 1.24% to 0.65%) and a0.17% (95% CI 0.14% to 0.21%) absolute reduction in 5-year risk of death due toCRC (from 0.21% to 0.04%). This corresponds to a 48% relative decrease in CRCincidence (risk ratio [RR] 0.52, 95% CI 0.34 to 0.76) and 81% decrease inmortality due to CRC (RR 0.19, 95% CI 0.07 to 0.47). In subgroup analyses, thereduction in the risk of death due to CRC was larger in women than men. Thereduction in CRC incidence was larger for complete colonoscopies and for leftsided cancers.Interpretation: Increased use of colonoscopy procedures isassociated with a reduction in the incidence and mortality of CRC in thepopulation.

659Colonoscopy Quality Indicators Colonoscopy in Australia: AReview of National DatasetsIan D. Norton*1, Cameron J. Bell1, Finlay A. Macrae2

1Gastroenterology, Royal North Shore Hospital, Sydney, NSW,Australia; 2Dept. Of Gastroenterology, Royal Melbourne Hospital,Melbourne, NSW, AustraliaThe Australian National Bowel Cancer Screening Program offers free immune-based FOBT to all residents aged 50,55 and 65. Bowel cancer screening isdependent upon high quality colonoscopy. However, there is little known aboutthe quality of colonoscopy in the Australian general community. To address thisissue the Medicare Australia database (which represents at least 75% ofcolonoscopy in Australia) and DRG data were queried regarding indices ofquality. Correlation was made with CRC statistics from Aust. Institute of HealthWelfare data sets. Colon cancer incidence is steady at about 60 per 105population (in spite of the ageing population) Approx. 560,000 colonoscopieswere performed in 2008-09 (1 in 36 of the population). Public sectorcolonoscopies are increasing at about 4.6% per year and private-sector rates atabout 7.7% per year. Approximately 58% of colonoscopies were performed bygastroenterologists, 30% by general or CR surgeons. 62% of procedures wereperformed on those aged 50-74yrs and 11% on those aged �75. Proceduralvolumes: Over 2008-09, of those billing for colonoscopy, 58% ofgastroenterologists and 21% of general/CR surgeons billed Medicare for �300procedures. Conversely, 11.2% of gastroenterologists, and 34% of gen./CRsurgeons billed fewer than 50 procedures/yr. Overall, 6500 colonoscopies (2.7%)were performed by proceduralists billing fewer than 50/yr. 424 practitionersbilled for fewer than 10 procedures. Polyp detection: Polypectomy rates aresteadily increasing from 28% in 2003-04 to 34% in 2008-09. Polyp retrieval forhistopathology: 76% of cases billed for colonoscopy with polypectomy wereassociated with a billing code for histopathology. Incomplete colonoscopy: 2500CT colonographies were billed following colonoscopy (ie: incompleteprocedure) (� 0.6% of the number of colonoscopies). This would excludesedation and prep. associated failure which usually result in repeat colonoscopy.Colonoscopy frequency: Over the 10yr period 1999-2009 68% of people havingcolonoscopy had 1 procedure, 20% had 2 procedures and 7.5% had 3procedures. Regional provision of colonoscopy: Colonoscopy rates in majorcities varied from 22-25/1000 population compared to outer regional (1.3-9.8/1000) and very remote (0-1.5/1000 pop.). However, incidence and mortality ofCR cancer over these different areas varied by less than 5%. Conclusion: Quality

Abstracts

AB155 GASTROINTESTINAL ENDOSCOPY Volume 75, No. 4S : 2012 www.giejournal.org