PP297 Management Of Sudden Onset Severe Headache Presenting To The Emergency Department: A Systematic Review
Bibliographic record
Abstract
Introduction Sudden onset severe headache is usually caused by a primary headache disorder but occasionally is secondary to a more serious problem, such as subarachnoid hemorrhage (SAH). Guidelines recommend non-contrast brain computed tomography (CT) followed by lumbar puncture (LP) to exclude SAH. However, guidelines pre-date the introduction of more sensitive modern CT scanners. A systematic review was undertaken to assess the clinical effectiveness of different care pathways for the management of headache in the Emergency Department. Methods Eighteen databases (including MEDLINE and Embase) were searched to February 2020. Studies were quality assessed using criteria relevant to the study design; most studies were assessed using the QUADAS-2 tool for diagnostic accuracy studies. Where sufficient information was reported, diagnostic accuracy data were extracted into 2 × 2 tables to calculate sensitivity, specificity, false-positive and false-negative rates. Where possible, hierarchical bivariate meta-analysis was used to synthesize results, otherwise studies were synthesized narratively. Results Fifty-one studies were included in the review. Eight studies assessing the accuracy of the Ottawa SAH clinical decision rule were pooled; sensitivity was 99.5 percent, specificity was 23.7 percent. The high false positive rate suggests that 76.3 percent SAH-negative patients would undergo further investigation unnecessarily. Four studies assessing the accuracy of CT within six hours of headache onset were pooled; sensitivity was 98.7 percent, specificity was 100 percent. CT sensitivity beyond six hours was considerably lower (≤90%; 2 studies). Three studies assessing LP following negative CT were pooled; sensitivity was 100 percent, specificity was 95.2 percent. LP-related adverse events were reported in 5.3–9.5 percent of patients. Conclusions The evidence suggests that the Ottawa SAH Rule is not sufficiently accurate for ruling out SAH and does little to aid clinical decision making. Modern CT within six hours of headache onset (with images assessed by a neuroradiologist) is highly accurate, but sensitivity reduces considerably over time. The CT-LP pathway is highly sensitive for detecting SAH, although LP resulted in some false-positives and adverse events.
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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 | 0.005 | 0.024 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.008 | 0.007 |
| Bibliometrics | 0.008 | 0.007 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.006 | 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; 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".