Effect of large-scale disasters on bystander-initiated cardiopulmonary resuscitation in family-witnessed, friend-witnessed and colleague-witnessed out-of-hospital cardiac arrest: a retrospective analysis of prospectively collected, nationwide, population-based data

IMPORTANCE: The effect of large-scale disasters on bystander cardiopulmonary resuscitation (BCPR) performance is unknown. OBJECTIVE: To investigate whether and how large-scale earthquake and tsunami as well as subsequent nuclear pollution influenced BCPR performance for out-of-hospital cardiac arrest (OHCA) witnessed by family and friends/colleagues. DESIGN AND SETTING: Retrospective analysis of prospectively collected, nationwide, population-based data for OHCA cases. PARTICIPANTS: From the nationwide OHCA registry recorded between 11 March 2010 and 1 March 2013, we extracted 74 684 family-witnessed and friend/colleague-witnessed OHCA cases without prehospital physician involvement. EXPOSURE: Earthquake and tsunamis that were followed by nuclear pollution and largely affected the social life of citizens for at least 24 weeks. MAIN OUTCOME AND MEASURE: Neurologically favourable outcome after 1 month, 1-month survival and BCPR. METHODS: We analysed the 4-week average trend of BCPR rates in the years affected and before and after the disaster. We used univariate and multivariate logistic regression analyses to investigate whether these disasters affected BCPR and OHCA results. RESULTS: Multivariable logistic regression for tsunami-affected prefectures revealed that the BCPR rate during the impact phase in 2011 was significantly lower than that in 2010/2012 (42.5% vs 48.2%; adjusted OR; 95% CI 0.82; 0.68 to 0.99). A lower level of bystander compliance with dispatcher-assisted CPR instructions (62.1% vs 69.5%, 0.72; 95% CI 0.57 to 0.92) in the presence of a preserved level of voluntary BCPR performance (23.6% vs 23.8%) was also observed. Both 1-month survival and neurologically favourable outcome rates during the impact phase in 2011 were significantly poorer than those in 2010/2012 (8.5% vs 10.7%, 0.72; 95% CI 0.52 to 0.99, 4.0% vs 5.2%, 0.62; 95% CI 0.38 to 0.98, respectively). CONCLUSION AND RELEVANCE: A large-scale disaster with nuclear pollution influences BCPR performance and clinical outcomes of OHCA witnessed by family and friends/colleagues. Basic life-support training leading to voluntary-initiated BCPR might serve as preparedness for disaster and major accidents.