Some values in the table in this article by Henry J M Barnett et al (5 June, pp 1539-43) were incorrect, due to an editorial error. The corrected version is given below. The revised values are those from the North American symptomatic carotid endarterectomy trial (NASCET).
Table.
Number needed to treat by endarterectomy to prevent one stroke in 2 years in patients with carotid stenosis
| No of patients in specified trial | Medical risk (%) at 2 years | Surgical risk (%) at 2 years | Risk difference (%) | Relative risk reduction (%) | No needed to treat* | Perioperative stroke and death rate (%) | |
|---|---|---|---|---|---|---|---|
| Symptomatic patients: | |||||||
| 70-99% (NASCET)33 | 659 | 24.5 | 8.6 | 15.9 | 65 | 6 | 5.8 |
| 70-99% (ECST)31** | 501 | 19.9 | 7.0 | 12.9 | 65 | 8 | 5.6 |
| 50-69% (NASCET)32 | 858 | 14.6 | 9.3 | 5.3 | 36 | 19 | 6.9 |
| 50-69% (ECST)31** | 684 | 9.7 | 11.1 | −1.4 | −14 | — | 9.8 |
| <50% (NASCET)32 | 1368 | 11.7 | 10.2 | 1.5 | 13 | 67 | 6.5 |
| <50% (ECST)31** | 1822 | 4.3 | 9.5 | −5.2 | −109 | — | 6.1 |
| Asymptomatic patients: | |||||||
| ⩾50% VA, men only45 | 444 | 7.7† | 5.6† | 2.1 | 27 | 48 | 4.4 |
| ACAS35 | 1662 | 5.0 | 3.8‡ (actual) | 1.2 | 24 | 83 | 2.6 |
| ACE43 | 1521 | 5.0§ (assumed) | 5.8 | −0.8 | - | - | 4.6 |
NASCET=North American symptomatic carotid endarterectomy trial; ECST=European carotid surgery trial; ACAS=asymptomatic carotid atherosclerosis study; ACE=aspirin and carotid endarterectomy trial.
Number of patients needed to treat by endarterectomy to prevent one stroke in 2 years after the procedure, compared with medical treatment alone.
By NASCET measurement. Additional data supplied by Dr P Rothwell.
Extrapolated from results.
Assigning a perioperative risk of 2.6% based on 724 of 825 patients who actually received endarterectomy in the surgical arm of ACAS, and utilizing the 0.6% risk of stroke in each of the two years after endarterectomy. The same 1.2% risk is assumed for the ACE patients and VA patients.
No medical arm—assumed from ACAS data.