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Abstract
Background: Colorectal cancer is a common and commonly lethal disease. Colonoscopy is the gold standard for detection of colorectal cancer (CRC) and its precursor lesions, as well as for evaluation of colonic mucosa for diagnosis and assessment of inflammatory bowel disease (IBD). Australia has amongst the highest rates of colonsocopy per capita of any country. The utility of colonoscopy can be improved in a number of areas.
This thesis examines a number of facets of colonoscopy to improve utility; improved methods of triage of colonoscopy, improving polyp detection using pharmacological methods, improving accuracy in assessing IBD during colonoscopy and minimising complications and physical harm at colonoscopy.
Methods: Numerous studies were undertaken. A prospective cohort study including 645 patients was used to examine the Asia Pacific Colorectal Screening Score (APCS) in triage of colonoscopy. A randomized double blind placebo controlled trial including 608 patients was used to examine hyoscine butylbromide induced spasmolysis to improve polyp detection at colonoscopy. A retrospective cohort study was used to examine 93 patients with acute severe colitis (ASC) and the ulcerative colitis endoscopic index of severity (UCEIS) to correlate this with treatment outcomes. A meta-analysis was undertaken of previous studies of prophylactic measures to reduce post polypectomy haemorrhage (PPH).
Results: The APCS is highly predictive of significant colonoscopic findings (RR 17.1 (95% CI 2.4-123; p=0.0001), and being underweight was protective of similar findings (OR 0.085, 0.011-0.625; p=0.015). Polyp detection was significantly improved (0.91 vs 0.70, p=0.044) by administering hyoscine butylbromide. UCEIS was correlated with outcomes of ASC and was highly predictive of the need for rescue therapy with biologic agents, colectomy and readmission (UCEIS 5 (3-8) vs 4 (3-7); p=0.0035). Meta-analysis demonstrated significant reductions in PPH with prophylactic measures, and an associate cost-benefit analysis confirmed cost saving with prophylaxis (RR for PPH with adrenaline vs placebo 0.28 (0.14-0.57, p<0.0001), NNT 12.3, cost to prevent one PPH USD1368.)
Conclusion: Numerous advances can now be recommended to improve the utility, triage, appropriate use, accuracy of reporting, yield of pathology, and prevention of complications. These measures would serve to make colonoscopy a safer, more cost effective and more useful diagnostic and therapeutic tool.