BackgroundThe effectiveness of public-use of automated external defibrillators in reducing the number of sudden cardiac death (SCD) cases at the national level is largely unknown. Our study aimed to evaluate whether the nationwide introduction of public-access-defibrillation (PAD) in 2004 affected the trend of annual sudden cardiac death (SCD) rates in Japan. MethodsThe number of nationwide SCDs occurring in people aged five years and older was extracted from Japanese demographic statistics (1995–2015). Segmented regression analysis was performed on the interrupted time series data stratified by age and sex to evaluate changes in trends of rates of annual SCDs after the PAD introduction in Japan. ResultsAfter the PAD introduction in 2004, we observed a significant decrease in trends of annual SCD rates for those aged 5–19 years (the ratio of trends between pre and post PAD introduction (RT) = 0.886, 95%CI: 0.801 to 0.980), 20–34 years (RT = 0.932; 95%CI: 0.906, 0.958), 35–49 years (RT = 0.953; 95%CI: 0.929, 0.977) and 50–64 years (RT = 0.971; 95%CI: 0.971, 0.991). However, the decrease was not observed for those aged 65 years and older. In the age and sex stratified analysis, there was a significant decrease in RT among males aged 5–64 years, and among females 35–49 years. ConclusionThe nationwide trend of annual rate of SCDs between 5 and 64 years old significantly decreased after the introduction of PAD in 2004 in Japan. Further, the reduction was more evident in males.