Age × Gender Interaction Effect on Resuscitation Outcomes in Patients With Out-of-Hospital Cardiac Arrest

Although an interaction between gender and age has been shown to influence resuscitation outcomes in patients with out-of-hospital cardiac arrest (OHCA), this interaction has not been investigated in Asian populations. In this prospective, observational study, data from all cases of OHCA in Japan between 2005 and 2012 were obtained from the Japanese National Registry. We determined the relative excess risk due to interaction and the ratio of odds ratios (ORs) to assess the interaction effect of gender and age on the incidence of return of spontaneous circulation (ROSC) before hospital arrival, 1-month survival, and neurologically intact survival 1 month after OHCA. Male gender was associated with decreased ROSC and lower 1-month survival rates in patients with OHCA of presumed cardiac origin. Older age was associated with lower 1-month and neurologically intact survival rates in male patients with OHCA of presumed cardiac and noncardiac origin and with increased ROSC in male patients with OHCA of presumed cardiac origin. The relative excess risk due to interaction for ROSC in patients with OHCA of presumed cardiac origin was statistically significant (OR 0.19, 95% confidence interval [CI] 0.06 to 0.32). The ratio of ORs for ROSC was statistically significant in patients with OHCA of presumed cardiac origin (OR 1.25, 95% CI 1.05 to 1.47) and of noncardiac origin (OR 0.40, 95% CI 0.17 to 0.92). In conclusion, the interaction effect between age and gender on ROSC was positive in OHCA cases of presumed cardiac origin and negative in those of noncardiac origin.