Critical appraisal:Hoff G, Grotmol T, Skovlund E, Bretthauer M, Norwegian Colorectal Cancer Prevention Study Group 2009 2

From Cancer Guidelines Wiki

Risk of bias assessment: Randomised Controlled Trial (Cochrane risk of bias tool)

Random sequence generation
Describe the method used to generate the allocation sequence in sufficient detail to allow an assessment of whether it should produce comparable groups.Jutta's question mark icon.png
drawn by individual randomisation

from the population registry
Not clear enough

What was the risk of bias from the random sequence generation?Jutta's question mark icon.png
Allocation concealment
Describe the method used to conceal the allocation sequence in sufficient detail to determine whether intervention allocations could have been foreseen in advance of or during, enrolment.Jutta's question mark icon.png
What was the risk of bias from the allocation concealment?Jutta's question mark icon.png
Describe all measures used, if any, to blind outcome assessors from knowledge of which intervention a participant received. Provide any information relating to whether the intended blinding was effective.Jutta's question mark icon.png
Assessment of both the cause of death and colorectal cancer staging for the

registries used was blinded to the group status of participants in the study.
Unsure what this means

What was the risk of bias from the blinding of participants and personnel and outcome assessors?Jutta's question mark icon.png
Incomplete outcome data
Describe the completeness of outcome data for each main outcome, including attrition and exlusions from the analysis. State whether attrition and exclusions were reported, the numbers in each intervention group (compared with total randomized participants), reasons for attrition/exclusions where reported, and any re-inclusions in analyses performed by the review authors.Jutta's question mark icon.png
Attrition and exclusion well explained; numbers excluded in control group were higher than for screening group but had same reasons for exclusion.
What was the risk of bias from incomplete outcome data?Jutta's question mark icon.png
Selective outcome reporting
State how the possibility of selective outcome reporting was examined by the review authors and what was found.Jutta's question mark icon.png
Mortality pre-specified in protocol and methods
What was the risk of bias from selective outcome reporting? Assessments should be made for each main outcome (or class of outcomes).Jutta's question mark icon.png
Other sources of bias
Describe any other sources of biasJutta's question mark icon.png
What was the risk of bias from other sources?Jutta's question mark icon.png
Overall risk of bias
Unclear risk of bias Additional comments: Please replace this text and include any additional comments in regards to your risk of bias rating

Jutta's tick icon.png This appraisal has been completed.

Hoff G, Grotmol T, Skovlund E, Bretthauer M, Norwegian Colorectal Cancer Prevention Study Group. Risk of colorectal cancer seven years after flexible sigmoidoscopy screening: randomised controlled trial. BMJ 2009 May 29;338:b1846 Abstract available at
Assigned to
Topic area
Guidelines:Colorectal cancer
Clinical question
Form:Quality appraisal rct-cochrane

Section below only relevant for Cancer Council Project Officer

Edit appraisal assignment