Future projections of temperature-related excess out-of-hospital cardiac arrest under climate change scenarios in Japan

Background: Recent studies have reported associations between global climate change and mortality. However, future projections of temperature-related out-of-hospital cardiac arrest (OHCA) have not been thoroughly evaluated. Thus, we aimed to project temperature-related morbidity for OHCA concomitant with climate change. Methods: We collected national registry data on all OHCA cases reported in 2005-2015 from all 47 Japanese prefectures. We used a two-stage time series analysis to estimate temperature-OHCA relationships. Time series of current and future daily mean temperature variations were constructed according to four climate change scenarios of representative concentration pathways ( RCPs) using five general circulation models. We projected excess morbidity for heat and cold and the net change in 1990-2099 for each climate change scenario using the assumption of no adaptation or population changes. Results: During the study period, 739,717 OHCAs of presumed cardiac origin were reported. Net decreases in temperature-related excess morbidity were observed under higher emission scenarios. The net change in 2090-2099 compared with 2010-2019 was -0.8% (95% empirical confidence interval [eCI]: -1.9, 0.1) for a mild emission scenario (RCP2.6), -2.6% (95% eCI: -4.4, -0.8) for a stabilization scenario (RCP4.5), -3.4% (95% ea: -5.7, -1.0) for a stabilization scenario (RCP6.0), and - 4.2% (95% eCI: -8.3, -0.1) for an extreme emission scenario (RCP8.5). Conclusions: Our study indicates that Japan is projected to experience a substantial net reduction in OHCAs in higher-emission scenarios. The decrease in risk is limited to a specific morbidity cause, and a broader assessment within climate change scenarios should consider other direct and indirect impacts. (C) 2019 Elsevier B.V. All rights reserved.