Critical appraisal:Farrell B, Godwin J, Richards S, Warlow C 1991
Risk of bias assessment: Randomised Controlled Trial (Cochrane risk of bias tool)
Random sequence generation
- Eligible patients were randomised by telephoning the Clinical Trial Service Unit in Oxford. A two letter code was allocated which matched coded medication packs held by the local hospital pharmacists. Each four month patient pack contained 20 one week foils of 28 tablets; two tablets were to be taken in the morning and two in the evening (preferably with or after food) and each pair of tablets was specifically labelled by the day of the week and whether it was to be taken in the morning or evening.
Patients who were randomised to "high dose" aspirin received two 300 mg tablets twice daily, those randomised to "low dose" aspirin received two 150 mg aspirin tablets in the morning and the two evening tablets were placebo, and those randomised to "placebo" received two placebo tablets twice daily.
- Eligible patients were randomised by telephoning the Clinical Trial Service Unit in Oxford. A two letter code was allocated which matched coded medication packs held by the local hospital pharmacists.
- Placebo used and taken at the same frequency as active drug.
Incomplete outcome data
- Follow-up seem to be very complete.
Patients were seen every four months until after the scheduled end of the trial (30 September 1986), their prior death or emigration. If they could not, or would not, come to the neurological clinics, follow up was continued by postal or telephone contact with their general practitioners. In addition, each patient was flagged with the Office of Population Censuses and Surveys so that we received a death certificate in the event of their death. All the surviving patients were reviewed after the 30 September 1986. This was to ensure that all important events had been recorded and to inform the patients of the interim trial results (but not of their own treatment as the collaborators were still "blind" at that time).
Selective outcome reporting
- Study outcomes in the initial paper clearly stated.
Other sources of bias
- Resonable large data set with very good follow-up during the trial period.
|Low risk of bias||Additional comments: Please replace this text and include any additional comments in regards to your risk of bias rating|
- Farrell B, Godwin J, Richards S, Warlow C. The United Kingdom transient ischaemic attack (UK-TIA) aspirin trial: final results. J Neurol Neurosurg Psychiatry 1991 Dec;54(12):1044-54 Available from: http://www.ncbi.nlm.nih.gov/pubmed/1783914.
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- Topic area
- Guidelines:Colorectal cancer/Primary Prevention
- Clinical question
- Form:Quality appraisal rct-cochrane
- Adverse events
Section below only relevant for Cancer Council Project Officer