Platelet antiaggregants in secondary prevention after stroke: Does dipyridamole add to the effect of aspirin?
Eleven randomized trials of platelet antiaggregant treatment, comprising 9,256 patients with a history of transient ischemic attacks or minor stroke, were identified. Trials without placebo controls were not included. Data were pooled based on two nonmutually exclusive groups: aspirin only and aspirin combined with dipyridamole. Each of these treatment groups was compared with a placebo group or with an aspirin group for the following nonmutually exclusive endpoints: (a) vascular events (stroke, myocardial infarction, vascular death) and (b) total strokes (including fatal and nonfatal stroke as well as cerebral hemorrhage). Aspirin was effective in preventing stroke or other vascular events after transient ischemic attacks. However, the risk reduction was small (about 15%), whereas the dosage used (900-1,500 mg vs. 75-300 mg) was not an influence. Placebo-controlled trials of aspirin in combination with dipyridamole indicated more effectiveness with a risk reduction of 30% for all vascular endpoints and 40% for the occurrence of stroke. There was no additional benefit of the combination in trials in the direct comparison with aspirin alone. Therefore, we contend that the benefit of aspirin with dipyridamole over aspirin alone has yet to be demonstrated in confirmative comparison studies.
From the Department of Neurology, Twenteborg Ziekenhuis, Almelo.
H J
HJ
Gelmers
The department of Clinical Epidemiology and Biostatistics, Academish Medisch Centrum, Amsterdam, The Netherlands.
J G
JG
Tijssen