PDF: CMOSS
(2023)Objective
To evaluate if extracranial-intracranial (EC-IC) bypass surgery plus medical therapy reduces stroke or death compared to medical therapy alone in patients with symptomatic internal carotid artery (ICA) or middle cerebral artery (MCA) occlusion and hemodynamic insufficiency.
Study Summary
• Patients were assigned to receive EC-IC bypass surgery plus medical therapy or medical therapy alone.
• The primary composite outcome of early stroke/death or late ipsilateral stroke at 2 years was not significantly different between groups (8.6% in the surgical group vs. 12.3% in the medical group).
• Surgery increased the early risk of stroke or death (6.2% vs. 1.8% at 30 days) but was associated with a lower risk of late ipsilateral stroke (2.0% vs. 10.3%).
Intervention
Extracranial-intracranial (EC-IC) bypass surgery plus optimized medical therapy versus optimized medical therapy alone in patients with symptomatic ICA or MCA occlusion and hemodynamic insufficiency. Follow-up was for 2 years.
Study Design
Arms: EC-IC bypass surgery plus optimized medical therapy (n=108) vs Optimized medical therapy alone (n=110)
Outcome
• The 30-day risk of stroke or death was higher with surgery (6.2% vs. 1.8%).
• The risk of ipsilateral ischemic stroke from 30 days to 2 years was lower with surgery (2.0% vs. 10.3%).
Bottom Line
Among patients with symptomatic ICA or MCA occlusion and hemodynamic insufficiency, the addition of EC-IC bypass surgery to medical therapy did not significantly reduce the composite risk of stroke or death within 30 days or ipsilateral ischemic stroke up to 2 years. The findings do not support the addition of EC-IC bypass surgery to medical therapy for this patient population.
Major Points
- CMOSS was a randomized, open-label trial with blinded outcome assessment, conducted at 13 centers in China.
- The trial enrolled 324 patients with symptomatic ICA or MCA occlusion and hemodynamic insufficiency, confirmed by computed tomography perfusion imaging.
- Patients were randomized 1:1 to receive either EC-IC bypass surgery plus medical therapy or medical therapy alone.
- The primary composite outcome was stroke or death within 30 days, or ipsilateral ischemic stroke from day 31 through 2 years.
- There was no significant difference in the primary outcome between the surgical and medical groups (8.6% vs. 12.3%; Hazard Ratio [HR], 0.71; P=.39).
- The surgical group had a higher risk of stroke or death within the first 30 days (6.2% vs. 1.8%), but a lower risk of ipsilateral ischemic stroke beyond 30 days (2.0% vs. 10.3%).
- None of the 9 prespecified secondary outcomes showed a significant difference between the groups.
Study Design
- Study Type
- Randomized, open-label, outcome assessor-blinded trial
- Randomization
- Yes
- Blinding
- The trial was open-label for the intervention, but the independent outcome committee and imaging core laboratory were blinded to treatment assignment.
- Sample Size
- 324
- Follow-up
- 2 years
- Centers
- 13
- Countries
- China
Primary Outcome
Definition: Composite of stroke or death within 30 days OR ipsilateral ischemic stroke beyond 30 days through 2 years after randomization.
| Control | Intervention | HR/OR | P-value |
|---|---|---|---|
| 12.3% (19/155) | 8.6% (13/151) | 0.71 (0.33-1.54) | 0.39 |
Limitations & Criticisms
- The trial was open-label, which introduces a potential for bias, although the outcome assessment was blinded.
- The enrolled population had a lower risk of events than was anticipated in the trial design, which may have underpowered the study to detect a clinically relevant difference.
- The study was conducted only in centers in China, and its generalizability to other populations is uncertain.
- The enrollment of women was suboptimal (20.7%).
Citation
JAMA. 2023;330(8):704-714.