Objective: Aneurysm treatment with endovascular coiling is associated with a better outcome than neurosurgical clipping in patients with subarachnoid haemorrhage (SAH). The better outcome after coiling may decrease the risk reduction from other treatments in these patients, and thus may increase sample sizes for current or future neuroprotective trials. The influence of the method of aneurysm treatment was studied in our randomised MASH trial, which assessed in a factorial design the efficacy of magnesium and aspirin in preventing delayed cerebral ischaemia (DCI) and poor outcome.
Methods: Between November 2000 and January 2004 315 patients were enrolled in the trial; 55 of them had no aneurysm treatment and were excluded for the current analysis, 176 underwent neurosurgical and 84 endovascular treatment. The effect of treatment on the risk of DCI was assessed by means of Cox proportional hazards modelling and that of poor outcome by means of logistic regression analysis.
Results: The hazard ratio of DCI with aspirin was 1.4 (95 % CI 0.3 - 1.7) after coiling and 1.9 (0.8 - 4.4) after clipping, and with magnesium 0.4 (0.1 - 1.2) after coiling and 0.8 (0.4 - 1.7) after clipping. The odds ratio of poor outcome with aspirin was 0.7 (0.2 - 2.9) after coiling and 0.8 (0.3 - 2.3) after clipping, and with magnesium 0.3 (0.1 - 1.0) after coiling and 0.8 (0.4 - 1.6) after clipping.
Conclusion: This post hoc analysis does not suggest that medical treatments are less effective after endovascular than after neurosurgical treatment in patients with SAH, and thus do not support a need for adjusting sample size calculations in future trials.