Summary of findings 1. Antiplatelet agent versus placebo for asymptomatic carotid stenosis.
| Antiplatelet agent compared to placeboa for asymptomatic carotid stenosis | |||||
| Patient or population: asymptomatic carotid stenosis Setting: outpatients Intervention: antiplatelet agent Comparison: placebo | |||||
| Outcomes (measurement) | № of participants (studies) | Certainty of the evidence (GRADE) | Relative effect (95% CI) | Anticipated absolute effects* (95% CI) | |
| Risk with placebo | Risk difference with antiplatelet agent | ||||
| Neurological impairment | The included study did not measure this outcome. | ||||
| Ipsilateral major or disabling stroke (CT scan or MRI) Follow‐up: 2.3 years |
372 (1 RCT)b | ⊕⊕⊝⊝ Lowc | RR 1.08 (0.47 to 2.47) | Study population | |
| 54 per 1000 | 4 more per 1000 (29 fewer to 80 more) | ||||
| Stroke‐related mortality (CT scan or MRI) Follow‐up: 2.3 years |
372 (1 RCT)b | ⊕⊕⊝⊝ Lowc | RR 1.40 (0.54 to 3.59) | Study population | |
| 38 per 1000 | 15 more per 1000 (17 fewer to 99 more) | ||||
| Major bleeding (not reported) Follow‐up: 2.3 years |
372 (1 RCT)b | ⊕⊝⊝⊝ Very lowc,d | RR 0.98 (0.06 to 15.53) | Study population | |
| 5 per 1000 | 0 fewer per 1000 (5 fewer to 79 more) | ||||
| Progression of carotid stenosis (DUS/every 6 months) Follow‐up: 2.3 years |
372 (1 RCT)b | ⊕⊕⊝⊝ Lowc | RR 1.16 (0.79 to 1.71) | Study population | |
| 201 per 1000 | 32 more per 1000 (42 fewer to 143 more) | ||||
| Adverse events (not reported) Follow‐up: 2.3 years |
372 (1 RCT)b | ⊕⊕⊝⊝ Lowc | RR 0.81 (0.41 to 1.59) | Study population | |
| 92 per 1000 | 16 fewer per 1000 (52 fewer to 47 more) | ||||
| Quality of life | The included study did not measure this outcome. | ||||
| *The risk in the intervention group (and its 95% CI) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; CT scan: computerised tomography scan; DUS: duplex ultrasonography; MRI: magnetic resonance imaging; №: number; RCT: randomised controlled trial; RR: risk ratio | |||||
| GRADE Working Group grades of evidence High certainty: we are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: we are moderately confident in the effect estimate; the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: our confidence in the effect estimate is limited; the true effect may be substantially different from the estimate of the effect. Very low certainty: we have very little confidence in the effect estimate; the true effect is likely to be substantially different from the estimate of effect. | |||||
aOne study included in this comparison bAcetylsalicylic acid cDowngraded two levels due to imprecision: few events, one study, and 95% CI consistent with possible benefit and possible harm dDowngraded one level due to indirectness: unexplained major bleeding definition