RESEARCH ARTICLE Open Access Methodological approach colonoscopy was associated with a reduction in CRC incidence (1.36 % vs. 0.84%) and mortality (0.23 % vs. 0.15%). For CRC

Full list of author information is available at the end of the articleincidence, the absolute risk reduction (ARR) associated with colonoscopy use was 0.52 % in an unadjusted model, 0.53% in a multivariate logistic regression model, 0.54 % in a propensity score-weighted outcome model, 0.56 % in propensity score-matched model, and 0.60 % using instrumental variable analysis. For CRC mortality, the ARR was 0.08 % in the unadjusted model, multivariate logistic regression model and for a propensity score- weighted outcome model, 0.10% using propensity score matched model and 0.17 % using the IVA model. Conclusions: Colonoscopy use reduced the risk of CRC incidence and mortality in the restricted cohort. The study highlights the importance of appropriate selection of study subjects and use of analytic methods for the evaluation of screening methods using observational data