Critical appraisal:Bjerrum A, Milter MC, Andersen O, Fischer A, Lynge E 2015 4

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Article
Bjerrum A, Milter MC, Andersen O, Fischer A, Lynge E. Risk stratification and detection of new colorectal neoplasms after colorectal cancer screening with faecal occult blood test: experiences from a Danish screening cohort. Eur J Gastroenterol Hepatol 2015 Dec;27(12):1433-7 Available from: http://www.ncbi.nlm.nih.gov/pubmed/26352132.
Assigned to
User:Victoria.freeman
Topic area
Guidelines:Colorectal cancer/Colonoscopy surveillance
Clinical question
Form
Form:Quality appraisal cohort risk factors
Outcomes
Incidence and risk of CRC, incidence and risk of advanced adenoma

Section below only relevant for Cancer Council Project Officer

Edit appraisal assignment

Risk of bias assessment: cohort study (risk factors)

Bias in selection of participants into study
Selection of the exposed and non-exposed cohorts
Drawn from the same population (low risk)
Bias due to error in exposure measurement
Measurement of exposure
Objective measurements from pre-existing records or <img alt="File:Jutta's info icon.png" src="/australiawiki_test/images/d/d9/Jutta%27s_info_icon.png" width="16" height="16"> baseline (Existing at or before baseline, where baseline is the time at which a participant is recorded to have entered the cohort or, if obtained after baseline, before onset of symptoms of the outcome or any likely effect of the developing outcome on the exposure) physical or biological assessment blind to outcome status (low risk)
Bias due to error in outcome measurement
Measurement of outcome
Outcome measurement unlikely to be influenced by exposure (low risk)
Was outcome of interest absent at the time to which the exposure refers?
Yes (low risk)
Was follow-up long enough for outcome to occur as a consequence of measured exposure? (Requires prior specification of a sufficient follow-up period)
Yes (low risk)
Bias due to non-participation
Participation rate in cohort
Participation rate in exposed cohort ≤10 percentage points different from non-exposed cohort OR exposed and non-exposed are from the same cohort (low risk)
Bias due to missing data
Completeness of follow-up of cohort
Active or passive follow-up with methods for ascertainment of one or more of outcome, death or emigration not described OR there was probably < 70% follow-up OR insufficient information to tell (high risk)
Accuracy of dates of outcome or censoring
Dates of outcome or censoring ascertained to within one year (low risk)
Difference in follow-up between exposed and non-exposed members of cohort
Follow-up methods are the same and likely to achieve the same completeness of follow-up in exposed and non-exposed participants (low risk)
Difference in missing data for exposure between those with or without the outcome
Difference in missing data for exposure < 10 percentage points (low risk)
Bias due to confounding
Comparability of exposed and non-exposed cohorts with respect to potentially important confounding variables (Requires prior specification of potentially important confounders)
Age and other potentially important confounders measured and controlled by design or in analysis (low risk)
Analysis bias
Covariates are appropriately included in statistical analysis models
Variables measuring the same underlying concept or lying in the same causal pathway ARE NOT included together as covariates in statistical analysis models (low risk)


Overall risk of bias
High risk of bias Additional comments: Please replace this text and include any additional comments in regards to your risk of bias rating
Comments

58 patients most likely had lost removed tissue arising from the colonoscopy procedure or transport of the specimen and could not be included in analysis (however, don't know what risk group they would fall in)