Estimated survival gains from pulselessness-detection technologies in unwitnessed out-of-hospital cardiac arrest in Western Australia: a simulation study

Abstract Background: In Australia, two-thirds of emergency medical service (EMS)-attended out-of-hospital cardiac arrests (OHCAs) are unwitnessed, and survival is < 5% in this group. With the recent incorporation of pulselessness-detection technologies into consumer wearable devices such as smartwatches, the potential exists to convert unwitnessed arrests into device-witnessed cases. Aim: To estimate the potential increase in survival if unwitnessed OHCAs were detected by a wearable device, leading to earlier notification of the EMS. Methods: We included EMS-attended, non-traumatic, bystander-witnessed and unwitnessed OHCAs that occurred in patients ≥ 16 years of age in Western Australia (WA) over a 5-year period (1 July 2020 - 30 June 2025). Counterfactual simulation modelling was used to estimate the number of 30-day survivors if an increasing proportion of unwitnessed OHCAs were detected using wearable devices. Our model included varying device sensitivities, ranging from 50-100%. Results: The study cohort comprised 11,450 cases. If 100% of unwitnessed cases were converted to device-witnessed, with 100% sensor sensitivity, we could expect 693 (95%CI: 538, 848) additional survivors over 5 years; corresponding to an increase in survival from 0.5% to 8.3% among unwitnessed OHCAs. If only 10% of unwitnessed cases were converted to device-witnessed, with a sensor sensitivity of 80%, we could expect 52 (95%CI: 8, 95) additional survivors in WA over 5 years; corresponding to a doubling in survival from 0.5% to 1.1% among unwitnessed arrests. Conclusion: Even a modest uptake of wearable devices with pulselessness-detection technology could lead to a doubling in 30-day survival among unwitnessed OHCA.