Nationwide Analysis of the Environmental Factors Associated with Out-of-hospital-cardiac-arrest

Background

Out-of-hospital-cardiac-arrest (OHCA), is a devastating event usually resulting in a patient`s death. Air-pollution has been found to be related to cardio-vascular morbidity, however its impact on OHCA occurrence is yet to be elucidated.

Aims

To investigate the association between ambient air-pollution and OHCA.

Methods

We analyzed all adult cases of OHCA in Israel identified by Magen-David-Adom (MDA) on-scene crews during 2016, as a function of air-pollution and meteorology from 102 monitoring stations nationwide.

We used time-Series and case-crossover approaches. Specifically, we used a Poisson regression to analyze an association between the daily OHCA events count, and environmental exposures on 1-7 days prior to event, and for each by region, separately.

In a case-crossover design we compared cases with 10 control hours 2-10 hours before and after every event. We used conditional logistic regression with OHCA cases and their controls.

Results

There were 12,858 OHCA cases (66.2% were pronounced dead-on-scene). The patients were 75.5±16.1 years old and 55.8% of them were males.

No adverse effect was found for environmental exposures on OHCA daily count.

In an hourly resolution of the case-crossover design, particular matter of aerodynamic diameter≥10µm (PM₁₀), (OR=1.037, pv<0.001) and solar radiation (SR) (OR=1.7, pv=0.002) were adversely related to OHCA.

An adverse impact of Ozone (0₃) was found during the summer, Jewish populated cities and the Negev district (OR=1.027, pv=0.021, OR=1.008, pv=0.075, and OR=1.204, pv=0.043, respectively). Nitrogen Dioxide (NO₂) was adversely associated with OHCA (OR=1.138, pv<0.001) during spring season. An adverse impact of PM with diameter<2.5μm (PM_2.5) was found in winter (OR=1.043, pv=0.013).

Conclusions

Environmental factors are adversely associated with OHCA, and the magnitude of its effect is modified by patients` demographic characteristic, seasonality and geographical areas.

Importance of the study

To help Emergency-Medical-Services (EMS) prepare for expected peaks in OHCA occurrence, and to provide recommendations for populations that are at higher risk for CV disease and Cardiac-arrest.

Keywords

OHCA, PM_2.5, PM₁₀, air-pollution