Spatiotemporal variation in the risk of out-of-hospital cardiac arrests in Queensland, Australia

Abstract

Background: Spatiotemporal analysis of out-of-hospital cardiac arrest (OHCA) risk is essential to design targeted public health strategies. Such information is lacking in the state of Queensland and Australia more broadly.

Methods: We developed a spatiotemporal Bayesian model accounting for spatial and temporal dimensions, space-time interactions, and demographic factors. The model was fit to data of all OHCA cases attended by paramedics in Queensland between January 2007 and December 2019. Parameter inference was performed using the integrated nested Laplace approximation method. We estimated and thematically mapped area-year risk of OHCA occurrence for all 78 local government areas (LGAs) in Queensland.

Results: We observed spatial variability in OHCA risk among the LGAs. Areas in the north half of the state and two areas in the south exhibited the highest risk; whereas OHCA risk was lowest in the west and south west parts of the state. Demographic factors did not have significant impact on the heterogeneity of risk between the LGAs. An overall trend of modestly decreasing risk of OHCA was found.

Conclusions: This study identified areas of high OHCA risk in Queensland, providing valuable information to guide public health policy and optimise resource allocation. Further research is needed to investigate the specifics of the areas that may explain their risk profile.

Keywords: Bayesian; Out-of-hospital cardiac arrest; Spatiotemporal model.

Fig. 1

Posterior temporal trend for the risk of out-of-hospital cardiac arrest in Queensland. Solid line is temporally structured effect [exp (γ_t)]; broken line is temporally unstructured effect [exp (δ_t)]. The lines represent the posterior means, and the shaded areas represent 95% credible intervals.

Fig. 2

Posterior mean for the spatial pattern of the risk of out-of-hospital cardiac arrest in Queensland.

Fig. 3

Posterior mean of the space-time interactions for the risk of out-of-hospital cardiac arrest in Queensland. For readability, only maps of 4 out of the 13 years are shown. Spatiotemporal effect for each individual year across the entire study period (13 years) is shown in Supplementary Fig. S8.

Fig. 4

Posterior mean of the relative risk of out-of-hospital cardiac arrest for each of the 78 local government areas (LGAs) over time. For readability, only maps of 4 out of the 13 years are shown. Maps of each individual year across the entire study period (13 years) are shown in Supplementary Fig. S9; and trend lines over time by LGA are shown in Supplementary Fig. S10.

Fig. 5

Map of exceedance probabilities (threshold = 1.5). For readability, only maps of 4 out of the 13 years are shown. Maps of each individual year across the entire study period (13 years) are shown in Supplementary Fig. S11.