Poor outcomes of out-of-hospital cardiac arrest at dinnertime in the elderly: Diurnal and seasonal variations

Purpose

To investigate differences in chronological variations in characteristics and outcomes of out-of-hospital cardiac arrests (OHCAs) between elderly and non-elderly patients.

Methods

We retrospectively analyzed bystander-witnessed OHCAs without prehospital involvement of physicians between January 2007 and December 2014 in Japan. We considered the following time periods: night-time (23:00–5:59) and non-night-time; we further divided non-night-time into dinnertime (18:00–20:29) and other non-night-time. Subsequently, we analyzed chronological variations in factors associated with OHCA survival using univariate and multivariable logistic regression analyses for unmatched and propensity-matched pairs, respectively.

Results

For elderly (≥65?years old, N?=?201,073) and non-elderly (≥10, <65?years old, N?=?57,124) OHCA patients, survival rates were lower during night-time than during non-night-time (elderly, 2.8% vs 1.6%; non-elderly, 9.8% vs 7.7%). The trend for incidences of bystander-witnessed OHCA in the elderly showed three peaks associated with breakfast-time, lunchtime, and dinnertime. However, a transient but considerable decrease in survival rates was observed at dinnertime (1.9% at dinnertime and 3.0% during other non-night-time). OHCAs in the elderly at dinnertime were characterized by low proportions of presumed cardiac etiologies and shockable initial rhythm. However,even after adjusting for these and other factors associated with survival,survival rates were significantly lower at dinnertime than during other non-night-time for elderly OHCA patients (adjusted odds ratio, 1.29; 95% confidence interval, 1.18–1.41, with dinnertime as reference). This difference was significant even after propensity matching with significant augmentation in winter.

Conclusions

Dinnertime, particularly in winter, is associated with lower survival in elderly OHCA patients.