A Cochrane review included 7 studies with a total of 1 385 subjects. Four of the trials were of good quality. The studied antiplatelet agents were acetylsalicylic acid (3 RCTs), OKY-046 (Cataclot), a selective thromboxane synthetase inhibitor (2 RCTs), dipyridamole (1 RCT) and ticlopidine (1 RCT). In six of the seven RCTs aneurysms were occluded by means of neurosurgical clipping only. In one RCT, also endovascular coiling was used on selected patients. For any antiplatelet agent there were reductions of a poor outcome (RR 0.79, 95% confidence interval (CI) 0.62 to 1.01) and secondary brain ischaemia (RR 0.79, 95% CI 0.56 to 1.22) and more intracranial haemorrhagic complications (RR 1.36, 95% CI 0.59 to 3.12), but none of these differences were statistically significant. There was no effect on case fatality (RR 1.01, 95% CI 0.74 to 1.37) or aneurysmal rebleeding (RR 0.98, 95% CI 0.78 to 1.38). For individual antiplatelet agents, only ticlopidine was associated with statistically significant fewer occurrences of a poor outcome (RR 0.37, 95% CI 95% CI 0.14 to 0.98) but this estimate was based on only one small RCT.
Comment: The quality of evidence is downgraded by limitations in study quality and by inconsistency (heterogeneity in interventions and outcomes).