Meta-analysis is a statistical technique for combining the findings of randomised trials which have addressed the same or a similar scientific question. This programme of meta-analyses aims to determine in detail, for a wide range of individuals, the benefits and risks of several of the most important drugs used for the treatment and prevention of cardiovascular disease.
In each meta-analysis, after identifying randomised trials relevant to the particular question of interest, we set up a collaboration among the principal investigators and trial sponsors, and a secretariat coordinates the collection of individual participant data (IPD), data checking, analysis and publication. In each case, new trial evidence is incorporated as it is published, and new analyses are published as the data mature.
Individual participant data often provide a more accurate understanding of treatment effects and disease mechanisms. In particular, they allow assessment of the effects of a drug on: particular outcomes (such as distinguishing between atherosclerotic and non-atherosclerotic cardiac events) defined similarly in each trial; on particular types of trial participants (for example the effects of statins in women, the elderly or those with chronic kidney disease), and over time, which often allows the net effects of treatment to be understood in terms of benefits and hazards occurring on different timescales.
Our work on meta-analysis of drugs with effects on vascular disease include collaborative meta-analyses concerned with the effects of antiplatelet drugs, such as aspirin, the effects of lowering blood cholesterol with statins, the benefits and risks of recombinant tissue plasminogen activator (rt-PA) for acute ischaemic stroke, as well as the adverse cardiovascular effects of non-steroidal anti-inflammatory drugs (NSAIDs), and the potentially beneficial effects of gastroprotectant drugs at reducing the risk of peptic ulcer bleeding. Our findings have been widely cited, have influenced treatment guidelines and drug labelling, and are having a major impact on public health. The meta-analyses have also helped to highlight outstanding uncertainties that require new randomised trials.