Meta-analysis is a valuable method of aggregating data sets of different trials which are inadequate or unconvincing on their own. There are strict rules on the retrieval and selection of data which are crucial in terms of the validity of a meta-analysis. Many so-called meta-analyses are flawed because of lack of a protocol or non adherence to it. Also underreporting of clinical trials is haunting the validity of meta-analysis. This hidden information is not a random process but is affecting mainly trials with negative results. To avoid this publication bias all clinical trials should enter an international online database.

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[Anti-aggregants in 1990].

Antiplatelet drugs are increasingly used in the prevention of arterial thrombosis. Aspirin in doses of circa 300 mg day may be recommended for the primary prevention of myocardial infarction, but only in subjects at moderate to high risk of cardiovascular disease. Antiplatelet agents are useless in stable angina, but aspirin reduced by about 50% the risk of myocardial infarction and the overall mortality rate among patients with unstable angina. A lower dose of aspirin (150 mg/day) also reduces mortality by 23% in the acute phase of myocardial infarction. In doses of 300 mg/day, aspirin is useful in the secondary prevention of myocardial infarction and reduces the overall mortality rate by 15%. Various antiplatelet agents, including aspirin (alone or combined with dipyridamole) and ticlopidine, have proved useful to avoid thrombosis in aorto-coronary grafts, provided treatment begins at the latest 6 hours after surgery. The usefulness of antiplatelets has been well established in the prevention of immediate reocclusion following coronary angioplasty, but not in the prevention of late reocclusion. Aspirin and ticlopidine are useful in the extracorporeal circulation techniques. In patients with cardiac valve prosthesis, antivitamin K anticoagulants are still indispensable, but their antithrombotic effect can be reinforced by dipyridamole or aspirin. Diuretics probably provide the best primary protection against cerebrovascular accidents, although medium doses of aspirin may be considered in elderly people at high risk of such accidents. Aspirin (alone or combined with dipyridamole) and ticlopidine may be recommended for the secondary prevention of cerebral ischaemic accidents.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗

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