1074 Ottawa Ankle rules cannot be safely used to rule out ankle fractures in patients who present ≥10 days post-injury
Bibliographic record
Abstract
Aims/Objectives/Background The Ottawa ankle rules (OAR) have been validated as a highly sensitive tool to rule out ankle fractures and reduce need for radiography. However, datasets validating OAR to date have excluded patients presenting ≥10 days post-injury and there is a need to ascertain if OAR can be safely used to rule out ankle fractures in this population. Methods/Design Patients presenting with ankle injuries to an emergency department (ED) in England between June 2015 and November 2020 were identified retrospectively through a clinical-coding search. Patient records were used to confirm the number of days between injury and presentation; those who presented ≥10 days post-injury were included for further analysis. Data was collected from ED documentation including region of pain, bony tenderness and weight-bearing status. OAR were used to categorise patients as ‘Ottawa-positive’, ‘Ottawa-negative’ or insufficient documentation. It was recorded whether the patient underwent radiography and whether the formal radiograph report confirmed a clinically-significant fracture. Patients who didn’t undergo radiography and didn’t subsequently re-present were deemed not to have a fracture. Data collected for each patient was checked and agreed by two authors. Results/Conclusions 6782 patients presented with ankle injuries, of which 126 patients presented ≥10 days post-injury. Of these 126 patients, 9 were Ottawa-positive, 90 were Ottawa-negative and 27 patients had insufficient documentation. 85 patients underwent radiography and 19 were found to have clinically-significant fractures. Of these fracture patients, 4 were Ottawa-positive and 15 were Ottawa-negative. Within our dataset, OAR demonstrated a sensitivity of 21.05%, specificity 93.75%, PPV 44.40% and NPV 83.30%. Using Fishers exact test, p=0.0658. OAR demonstrate poor sensitivity and cannot be safely used to rule out ankle fractures in patients who present ≥10 days post-injury. However, due to the p-value and low power there may be a risk of type 2 error and a larger study may prove otherwise.
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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 | 0.004 | 0.025 |
| Meta-epidemiology (narrow) | 0.000 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.003 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.002 |
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".