WHAT THIS STUDY ADDS
death, bleeding
EVENTS, BLEEDING, MINOR
By applying an algorithm to UK routinely collected hospitalisation and death registry data, it may be feasible to categorise bleeding events as major or minor.Randomised comparisons using routine data only found estimated relative and absolute effects of allocation to aspirin versus placebo on major bleeding similar to adjudicated follow-up.If all bleeding events recorded in the routine data had been considered major, the significant bleeding hazard would have been missed.