The Problem of Subgroup Analyses: An Example from a Trial on Ruptured Intracranial Aneurysms
Bibliographic record
Abstract
The randomized ISAT demonstrated the superiority of endovascular treatment in patients with ruptured intracranial aneurysms considered suitable for either clipping or coiling. A later publication proposed a second look at the results, demonstrating that older patients with ruptured MCA aneurysms appeared to benefit from clipping, in disagreement with the general findings of the trial. Subgroup analyses in randomized trials and observational studies examine whether effects of interventions differ between subgroups according to the characteristics of patients. However, many apparent subgroup effects have been shown to be spurious. Misleading subgroup effects can result in withholding efficacious treatment from patients who would benefit or can encourage ineffective or potentially harmful treatments for patients who would fare better without. Some guidelines for the prudent interpretation of subgroup findings are reviewed.
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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 | 0.314 | 0.530 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.005 | 0.010 |
| Bibliometrics | 0.004 | 0.005 |
| Science and technology studies | 0.002 | 0.005 |
| Scholarly communication | 0.004 | 0.005 |
| Open science | 0.003 | 0.004 |
| Research integrity | 0.009 | 0.013 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
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; the direct Gemma label and the distilled Codex classifier agree on what is shown here.
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".