Effect of night-time onset on neurologically favourable survival between patients with and without bystander cardiopulmonary resuscitation

Backgrounds Patients with out-of-hospital cardiac arrest (OHCA) during the night tend to have worse outcomes than those with OHCA during the day. One possible explanation for poorer outcomes in patients with night-time onset is the lower quality of bystander cardiopulmonary resuscitation (CPR), although the exact cause has not been fully clarified. Purpose This study evaluated the differences between day and night-time-OHCA onset on neurologically favourable survival for patients with and without bystander CPR. We also evaluated the relationship between time from collapse to prehospital return of spontaneous circulation (ROSC) and the effect of night-time admission on neurologically favourable survival. Methods A cohort of 137,465 patients with witnessed OHCA and prehospital return of spontaneous circulation (ROSC) was obtained from a nationwide OHCA registry database. The primary endpoint was neurologically favourable survival at 1 month. We investigated the impact of night-time bystander CPR presence or absence as a sub-analysis. To investigate the impact of the time from collapse to prehospital ROSC and night-time onset on neurologically favourable survival, we evaluated the odds ratio (OR) and 95% confidence interval (CI) for neurologically favourable survival during night-time compared to daytime across each time interval from collapse to prehospital ROSC using univariable and multivariable logistic regression analyses. Results The neurologically favourable survival rate was significantly lower for patients with night-time than those with daytime OHCA onset (30.5% vs. 31.4%, p<0.001). (Table) The multivariable analysis determined night-time OHCA onset was a significant negative factor associated with neurologically favourable survival at 1-month (OR 0.96; 95% CI 0.93–0.99, p=0.008). This negative effect of night-time onset was more pronounced for patients with bystander CPR from a citizen (OR 0.93; 95% CI 0.89–0.97, p=0.001). In contrast, this negative effect was attenuated in patients without bystander CPR (OR 0.99; 95% CI 0.96–1.04, p=0.827). Furthermore, night-time OHCA onset had a negative effect on neurologically favourable survival only when ROSC was achieved within 5–10 minutes. (Figure) Conclusions Even among patients with witnessed OHCA and prehospital ROSC, neurologically favourable survival rates were significantly lower for patients who experienced night-time OHCA than for those who experienced daytime OHCA. Additionally, this effect was especially pronounced in patients who received bystander CPR from a citizen and those who achieved ROSC between 5 and 10 minutes, which suggests that the insufficient quality of bystander CPR may be one of the causes for the negative impact of night-time on patients with OHCA.