Overall results of a pooled analysis of individual patient data from trials of endarterectomy for symptomatic carotid stenosis
Bibliographic record
Abstract
64 Carotid endarterectomy (CEA) is beneficial for severe symptomatic stenosis, but trial results for moderate stenosis have been conflicting. This may be due to the differences between trials in the method of measurement of carotid stenosis, differences in outcome definitions, or chance. We used the same definitions of outcomes and the same method of measurement of stenosis to pool individual patient data on over 95% of patients ever randomised in trials of CEA for symptomatic stenosis: European Carotid Surgery Trial (ECST); North American Symptomatic Carotid Endarterectomy Trial; Veterans Administration trial #309. The degree of stenosis was remeasured on the 3018 pre-randomisation ECST angiograms by the method used in the other two trials. Remeasurements correlated well with the original measurements (r=0.94, P<0.00001). Data were merged on 6092 patients with 1711 strokes and 1493 deaths during 35,000 patient years of follow-up. Patients were categorised according to the degree of symptomatic stenosis: <30% (n=1755); 30–49% (n=1441); 50–69% (n=1547); 70–99% (n = 1338); occlusion (n = 9); unknown (n=2). Surgery was harmful in patients with <30% stenosis, and was of no benefit in patients with 30–49% stenosis. Surgery reduced the risk of any stroke or surgical death in patients with 50–69% stenosis (NNT = 14, 95% CI = 8–30), and this was consistent across the individual trials. Surgery was highly beneficial in patients with 70–99% stenosis (NNT = 8, 95% CI = 5–12), but had no effect on overall survival. Operative mortality was 1.1% (95% CI = 0.9–1.4) and the operative risk of stroke and death was 7.0% (95% CI = 6.2–8.0). In contrast to interpretations of the original trial reports, by using the same outcome definitions and the same method of measurement of stenosis we have demonstrated that the trial results are entirely consistent. By combining all available trial data we have determined the effect of surgery with greater precision. CEA reduces the risk of any stroke or death in patients with 50–99% carotid stenosis, although benefit is less than for 70–99% stenosis.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.067 | 0.105 |
| Meta-epidemiology (narrow) | 0.006 | 0.003 |
| Meta-epidemiology (broad) | 0.026 | 0.062 |
| Bibliometrics | 0.007 | 0.007 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.004 | 0.004 |
| Open science | 0.001 | 0.003 |
| Research integrity | 0.003 | 0.003 |
| Insufficient payload (model declined to judge) | 0.006 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".