Critical appraisal:Van Kruijsdijk RC, Visseren FL, Ridker PM, Dorresteijn JA, Buring JE, van der Graaf Y, et al 2015

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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
The 65 169 women who were willing and eligible entered a 3-month run-in period using both placebo aspirin and placebo vitamin E to identify likely long-term compliers to pill taking. A total of 39 876 women remained willing and eligible, were compliant during run-in, and were randomized into the trial (19 934 to aspirin and 19 942 to placebo). Randomization used blocks of size 16 within 5-year age strata and took place from April 30, 1993, through January 24, 1996.
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
Participants were sent an annual supply of monthly calendar packs containing active agents or placebo. Every 6 months for the first year, then every 12 months subsequently, participants were sent questionnaires seeking information on compliance, adverse effects, occurrence of relevant clinical end points, and risk factors. Study medications and end point ascertainment were continued in blinded fashion through the scheduled end of the trial on March 31, 2004.
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
All participants were followed up for the occurrence of cancer or cardiovascular events. Following a report of cancer by questionnaire or death certificate, written consent for medical record review was requested from the participant, or next of kin if deceased, and medical records were obtained from hospitals or treating physicians. All relevant information was reviewed by the WHS Endpoints Committee composed of physicians blinded to treatment assignment.
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
Information on outcomes was collected and confirmed in a similar manner as during the trial period. End point review is complete for 95% of reported cancer cases, 95% of myocardial infarctions, and 94% of strokes. The confirmation rate among participants with records is 82% for cancer, 61% for myocardial infarction, and 68% for stroke. For the present study, only events confirmed by medical records and deaths with confirmed cause were used. Reports of gastrointestinal bleeding were collected intermittently during posttrial follow-up and were not confirmed[4]. The present analyses include end points accrued and confirmed through 14 March 2012, using data of participants who provided an adequate baseline plasma sample (n=27,939).
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
Information on outcomes was collected and confirmed in a similar manner as during the trial period. End point review is complete for 95% of reported cancer cases, 95% of myocardial infarctions, and 94% of strokes. The confirmation rate among participants with records is 82% for cancer, 61% for myocardial infarction, and 68% for stroke. For the present study, only events confirmed by medical records and deaths with confirmed cause were used. Reports of gastrointestinal bleeding were collected intermittently during posttrial follow-up and were not confirmed[4]. The present analyses include end points accrued and confirmed through 14 March 2012, using data of participants who provided an adequate baseline plasma sample (n=27,939).
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
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
van Kruijsdijk RC, Visseren FL, Ridker PM, Dorresteijn JA, Buring JE, van der Graaf Y, et al. Individualised prediction of alternate-day aspirin treatment effects on the combined risk of cancer, cardiovascular disease and gastrointestinal bleeding in healthy women. Heart 2015 Mar;101(5):369-76 Available from: http://www.ncbi.nlm.nih.gov/pubmed/25475110.
Assigned to
User:Albert.chetcuti
Topic area
Guidelines:Colorectal cancer
Clinical question
Form
Form:Quality appraisal rct-cochrane
Outcomes
Colorectal Cancer risk
Clinical trial
WHS

Section below only relevant for Cancer Council Project Officer

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