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Proposal 1542

Title of the Proposed Research

Optimising the Analysis of vascular Prevention trials (OA-Prevention)

Lead Researcher

Philip Bath


University of Nottingham

Funding Source

Institutional funding

Potential Conflicts of Interest


Data Sharing Agreement Date

25 January 2017

Lay Summary

Prevention trials typically count outcomes as dichotomous events (e.g. stroke – no stroke) although this is inefficient statistically and gives no indication on the severity of recurrent events. We hypothesise that vascular events may be polychotomised with ordering determined by severity, e.g. stroke categorised as fatal-severe-mild-TIA-no stroke. In a pilot study using published summary trial data, ordinal analysis of these ordered categorical outcomes was more efficient statistically than current binary approaches. We plan to further test this concept using individual patient data from vascular prevention trials, not least because many publications do not provide sufficient granular data. We will identify relevant trials and generate ordered vascular outcomes. We will then compare binary and ordinal statistical methods of analysis, both unadjusted and adjusted, then compare sample size estimates and number-needed-to-treat for these trials using published binary and ordinal methods. If these ordinal approaches are superior, future trials should consider using stroke and other vascular outcomes as ordered categories, and should be analysed using ordinal (or even linear) statistical tests. Using this approach, future trials could potentially be smaller (thereby reducing trial costs and competition for patient recruitment) and provide extra information on the effect of treatment on the severity, as well as frequency of vascular events. This information will be vital for patients, carers, healthcare professionals, and Government.

Study Data Provided

BI-1160.20: PETRO Stroke Prevention in Patients With AF by Treatment With Dabigatran, With and Without Aspirin, Compared to Warfarin
BI-1160.26:Randomized Evaluation of Long Term Anticoagulant Therapy (RE-LY) With Dabigatran Etexilate

Statistical Analysis Plan

Publication Citation

The publication citation will be added after the research is published.

Summary Results

Results summary or link will be posted when available.