Twelve-month follow-up of the Cervical Artery Dissection in Stroke Study (CADISS) has confirmed its earlier findings – that there is no difference in efficacy between antiplatelet or anticoagulant drugs in preventing stroke and death.

The study, published in JAMA Neurology, enrolled 250 patients with symptomatic carotid and vertebral artery dissection from specialised stroke centres in the UK and Australia.

Patients were randomised to either anti-platelet drugs, including aspirin, clopidogrel, or dipyridamole or a dual combination, or anticoagulation therapy, typically heparin followed by warfarin. Novel oral anticoagulants were not used at the time of the study.

Stroke was found to be a rare outcome at both time points – 2% at three months in the earlier study and 2.5% at 12 months in the current study.

The follow-up study found no significant differences between treatment arms in outcomes including ipsilateral stroke, ipsilateral stroke or TIA, any stroke or TIA, and any stroke or death.

“Although there were 4 strokes within 1 year of follow-up in the AP group and only 2 in the AC group, this was counterbalanced by 1 major hemorrhage in the AC group,” the study said.

The researchers said the low number of endpoints meant that a very large sample size would be required to detect a treatment difference between the two therapies.

However the low rate of events also suggested that ‘any absolute effect on outcome, even if, for example, there was a 25% reduction in risk, would be very low’.

“Therefore, it seems reasonable to treat such patients with either anticoagulant or antiplatelet agents based on the available data.”

The researchers noted that 55% of patients in the antiplatelet group received monotherapy versus dual antiplatelet drugs.

“Increasing evidence suggests that the combination of aspirin and clopidogrel may be more effective in preventing early recurrent stroke risk in patients with atherosclerotic large artery stenosis, and it is possible that AP may have been more effective if all patients had been given this combination.”