Validation of the naloxone cardiac arrest decision instrument for identifying opioid-associated cardiac arrests.
Resuscitation · 2025-10-06 · Method & validation
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.
Tags
Antidotes · Decision support tools · Naloxone · Paramedics & EMTs