Regional variations in out-of-hospital cardiac arrest outcomes after the Great East Japan Earthquake: a 16-year cohort study

Abstract Large-scale disasters may disrupt community responses to out-of-hospital cardiac arrest (OHCA). However, long-term regional patterns of OHCA outcomes following compound disasters involving nuclear contamination remain unclear. We examined 188,783 family-, friend-, or colleague-witnessed OHCA cases in eastern Japan between 11 March 2007 and 10 March 2023 using nationwide, prospectively collected Utstein-style registry data. Regions were categorised as Fukushima, Iwate/Miyagi/Ibaraki, and other eastern Japanese prefectures based on tsunami damage and radioactive soil contamination. Trends were assessed across five periods from before the Great East Japan Earthquake to the COVID-19 pandemic. The primary outcome was neurologically favourable 1-month survival. During intensive reconstruction, crude survival rates were similar in Fukushima, Iwate/Miyagi/Ibaraki, and other eastern Japanese prefectures (4.40%, 4.69%, and 5.08%, respectively). During the post-intensive reconstruction/pre-pandemic period, survival was 3.10% in Fukushima, compared with 6.39% in Iwate/Miyagi/Ibaraki and 6.03% in other eastern Japanese prefectures; the adjusted odds ratio (aOR) for Fukushima versus Iwate/Miyagi/Ibaraki was 0.48 (95% confidence interval [CI], 0.36–0.64). During the pandemic, the rate remained lowest in Fukushima (2.35%), with an aOR of 0.46 (95% CI, 0.32–0.67) versus Iwate/Miyagi/Ibaraki. These findings demonstrate persistent regional differences in OHCA outcomes. However, the mechanisms underlying these differences could not be determined from available data.