Prospective External Validation of an AI-Based Emergency Department Pneumonia Disposition Prediction Tool
Bibliographic record
Abstract
Purpose: This shadow deployment evaluated an externally-developed AI tool to predict disposition using chest X-rays (CXR) in patients with community-acquired pneumonia (CAP) in the Emergency Department (ED). Retrospective and prospective external validations were conducted to assess differences between the 2 evaluations and across subgroups to inform deployment decisions. Methods: The CNN was retrospectively validated (n = 17 689) from November 1, 2020, to June 30, 2021, and prospectively validated on “suspected-CAP” patients (n = 3062) from Jan 1 to Jan 31, 2023. Calibration and standard metrics, including AUC, accuracy, sensitivity, specificity, PPV, and NPV, were calculated. Subgroup analyses were conducted for age, sex, modality, and CXR projection (PA vs AP). Results: The model’s AUC was 67% in both validations. The prospective evaluation showed a non-significant increase in sensitivity (65% vs 59%) and PPV (64% vs 63%), while specificity (68% vs 73%) and NPV (69% vs 70%) slightly decreased. NPV was very high for younger patients in the prospective evaluation (95%); PPV was moderately high for older patients (81%). Sensitivity dropped significantly in females under 31 years (50%), and specificity was reduced in females over 86 years (38%). Conclusion: This study showed moderate, consistent performance in both retrospective and prospective validations. While this consistency is encouraging, further direct comparisons are needed to determine whether both validation approaches are necessary in different clinical settings. Subgroup analysis suggests the tool may be helpful to accelerate discharge in younger patients (high NPV) and possibly for admission in older patients (high PPV).
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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 | 0.021 | 0.043 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".