The Effect of Rurality on Out-of-Hospital Cardiac Arrest Resuscitation Incidence: An Exploratory Study of a National Registry Utilizing a Categorical Approach

Purpose: Variation in incidence is a universal feature of out-of-hospital cardiac arrest (OHCA). One potential source of variation is the rurality of the location where the OHCA incident occurs. While previous work has used a simple binary approach to define rurality, the purpose of this study was to use a categorical approach to quantify the impact of urban-rural classification on OHCA incidence in the Republic of Ireland. Methods: The observed versus expected ratio of OHCA incidence where resuscitation was attempted for the period January 1, 2012, to December 31, 2014, was calculated for each of the 3,408 electoral divisions (ED). EDs were then classified into 1 of 6 urban-rural classes. Multilevel modeling was used to test for variation in incidence ratios (IR) across the urban-rural classes. Findings: A total of 4,755 cases of adult OHCA, not witnessed by Emergency Medical Services, where resuscitation was attempted were included in the study. The number of EDs in each category was as follows: city (n = 477); town (n = 293); near village (n = 182); remote village (n = 84); near rural (n = 1,479); remote rural (n = 893). The IR per ED varied from 0 to 18.38 (EDs, n = 3,408). Multilevel modeling showed that 2.36% of variation in IR was due to urban-rural classification. This dropped to 0.45% when adjusted for ED deprivation score and median distance to an ambulance station. The addition of other explanatory variables did not improve the model. Conclusion: OHCA variation in Ireland is limited and almost fully explained by area-level deprivation and proximity to ambulance stations.