Validation of the naloxone cardiac arrest decision instrument for identifying opioid-associated cardiac arrests
Bibliographic record
Abstract
BACKGROUND: Up to fifteen percent of out-of-hospital cardiac arrests (OHCAs) are precipitated by occult drug overdose - cases without history or evidence of drug use that are often attributed to a non-overdose cause. The NAloxone Cardiac ARrest Decision Instrument (NACARDI) was derived to help emergency medical service (EMS) providers rapidly identify patients at higher risk of occult opioid-associated (OA)-OHCAs during resuscitation. In this analysis we externally validate NACARDI in an independent cohort of OHCA patients. METHODS: We conducted a retrospective validation using data from EMS-attended OHCA patients and coroner records in Ontario, Canada between 2020-2021. Inclusion criteria were age ≥18 years and OHCA death with a coroner record. Exclusion criteria were EMS-suspected drug overdose or known cause of the OHCA. NACARDI consists of two criteria: patient age and unwitnessed cardiac arrest. Two cut-offs for patient age were assessed for this validation: <50 years (NACARDI-50) and <60 years (NACARDI-60). The primary outcome was coroner adjudicated cause of death. We calculated screening characteristics and receiver operating characteristic (ROC) curves using standard formulae. RESULTS: Of 2904 OHCA cases without an obvious cause, 791 had coroner evaluations and 121 (15.3 %) were adjudicated as occult OA-OHCA. NACARDI-60 had: sensitivity 82.6 % (95 %CI 74.9-88.4 %), specificity 77.1 % (95 %CI 73.8-80.1 %), negative predictive value 96.1 % (95 %CI 94.1-97.4 %), and positive predictive value 39.4 % (95 %CI 33.6-45.5 %). NACARDI-50 had: sensitivity 63.6 % (95 %CI 54.4-72.2 %), specificity 89.3 % (95 %CI 86.7-91.5 %), negative predictive value 93.2 % (95 %CI 90.9-95.0 %), and positive predictive value 51.7 % (95 %CI 43.4-59.9 %). ROC curves for both NACARDI-50 and NACARDI-60 demonstrated excellent discrimination for occult OA-OHCA. CONCLUSION: In this external validation cohort, NACARDI had a sensitivity and specificity sufficiently high to aid in the real-time identification of occult OA-OHCA in the field. NACARDI has the potential to guide targeted interventions for OA-OHCA.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".