Critical appraisal:Rothwell PM, Wilson M, Elwin CE, Norrving B, Algra A, Warlow CP, et al 2010 2

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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
Allocation to treatment was done randomly through computer generated random numbers balanced between the four treatment groups (two in the non-factorial stage) within each practice. The period of screening, identification, and notification of risk status took 9 months on average. All those considered at high risk were randomly assigned a putative treatment group so that those eligible and willing to enter the treatment phase could start treatment immediately.
What was the risk of bias from the random sequence generation?Jutta's question mark icon.png
Low
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
Allocation to treatment was done randomly through computer generated random numbers balanced between the four treatment groups (two in the non-factorial stage) within each practice. The period of screening, identification, and notification of risk status took 9 months on average. All those considered at high risk were randomly assigned a putative treatment group so that those eligible and willing to enter the treatment phase could start treatment immediately.
What was the risk of bias from the allocation concealment?Jutta's question mark icon.png
Low
Blinding
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
Active and placebo tablets were identical in appearance. Labels placed on the containers of warfarin and calendar packs of aspirin by the suppliers and to indicate whether they were active or placebo were removed in the coordinating centre dispensing room and replaced by each man’s name and study number. Supplies were then distributed to the participating practices.
What was the risk of bias from the blinding of participants and personnel and outcome assessors?Jutta's question mark icon.png
Low
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
All participates lost to attrition were mentioned. This was substantial across the 4 treatment groups, but was equally so.
What was the risk of bias from incomplete outcome data?Jutta's question mark icon.png
Low
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
Study outcomes are long term follow-up related to CRC.
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
Low
Other sources of bias
Describe any other sources of biasJutta's question mark icon.png
None to report
What was the risk of bias from other sources?Jutta's question mark icon.png
Low
Overall risk of bias
Low 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.


Article
Rothwell PM, Wilson M, Elwin CE, Norrving B, Algra A, Warlow CP, et al. Long-term effect of aspirin on colorectal cancer incidence and mortality: 20-year follow-up of five randomised trials. Lancet 2010 Nov 20;376(9754):1741-50 Available from: http://www.ncbi.nlm.nih.gov/pubmed/20970847.
Assigned to
User:Albert.chetcuti
Topic area
Guidelines:Colorectal cancer
Clinical question
Form
Form:Quality appraisal rct-cochrane
Outcomes
CRC mortality
Clinical trial
Clinical trial:TPT Trial
Notes
Critically appraise the long term follow up for the TPT Trial. Original trial data publication http://wiki.cancer.org.au/australia/Citation:Meade_TW,_Wilke_HC,_Kelleher_CC,_Roderick_PJ,_Brennan_PJ,_Wilson_CW,_et_al_1998

Section below only relevant for Cancer Council Project Officer

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