Abstract Body: Background
Intra-arrest transport (IAT), the practice of transporting out-of-hospital cardiac arrest (OHCA) to hospital with ongoing compressions, is associated with poor outcomes. No prior studies have assessed IAT in rural versus urban communities. Higher IAT rates could explain known disparities in survival between these regions.

Aims and Hypothesis
We aimed to estimate the association of rurality and the minute-by-minute probability of IAT versus continued on-scene resuscitation between 0-20 min. and 20-90 min. after EMS arrival at the curb. We hypothesized increased hazard of IAT in rural and small-town census tracts in each time segment.

Methods
Using the CARES registry, we included adult, non-EMS-witnessed OHCA occurring from 2021-2023 who were pulseless when EMS arrived on-scene. Agencies submitting <30 cases over the study period or missing >10% of sustained return of spontaneous circulation (S-ROSC) timestamps were excluded. We categorized census tracts as urban, suburban, large town, small town, and rural. Cox proportional hazards models, accounting for clustering by agency, calculated the hazard of IAT at each min. in those yet to achieve S-ROSC or have efforts terminated. Adjusted hazard ratios (aHR) and 95% confidence intervals (CI) were calculated for 0-20 (“expedited”) and 20-90 (“late”) min. with adjustment for known risk factors of IAT and testing for interaction by initial rhythm.

Results
Of 93,446 OHCA, 27.3% were treated with IAT (28.5% urban, 20.9% small town, and 19.3% rural) [Fig. 1]. Notable variations across rurality groups included race (Black race: 16.7% urban, 8.2% small town, and 5.3% rural), bystander-witnessed (41.3% urban, 51.7% small town, and 52.0% rural), and initial shockable rhythm (18.5% urban, 21.8% small town, and 20.5% rural). Compared with urban census tracts, there was evidence of lower expedited IAT in rural (aHR 0.79; 95% CI 0.59 - 1.05) and small town (aHR 0.68; 95% CI 0.51 – 0.89) census tracts. This difference was larger for late IAT in both rural (aHR 0.57; 95% CI 0.45-0.72) and small town (aHR 0.53; 95% CI 0.41-0.69). Interaction by initial rhythm was found, with rural initial shockable rhythms having similar rates of expedited and late IAT as urban [Table 1].

Conclusion(s)
Compared with urban census tracts, rural and small town communities had lower rates of IAT, especially late in professional resuscitation. This suggests that an increased rate of IAT is unlikely to explain rural vs. urban disparities.