Does time of day influences outcome in out-of-hospital cardiac arrest patients?: A meta-analysis of cohort studies.

BACKGROUND

Whether time of day has impact on outcomes after out-of-hospital cardiac arrest (OHCA) remains controversial. However, there are no evidence syntheses describing the impact of time differences on outcomes from OHCA.

METHODS

A meta-analysis of cohort studies exploring the association between time of day and survival in patients with OHCA was performed. Odds ratios (ORs) with 95% confidence intervals (CIs) were pooled using a random-effects model.

RESULTS

Ten studies involving 252,848 patients and 24,646 survivals were included. Patients with night-time OHCA had significantly lower short-term survival compared to patients with daytime OHCA (OR, 1.20; 1.07-1.36; P < .001). The relationship between temporal differences and survival was consistent in most subgroups. For long-term survival, it remained unclear whether night-time was associated with reduced OHCA survival at 12 months (OR, 1.47; 0.71-3.06; P < .001). Three studies including 183,129 patients examined the association between weekend and survival in OHCA patients. Survival did not differ on weekends compared to weekdays (OR, 1.00; 0.9 7-1.04; P = .918).

CONCLUSIONS

Night-time is associated with a lower survival in OHCA patients. However, similar findings are not observed in OHCA patients on weekends. Caution is required in interpretation of these results accounting for high level of heterogeneity and large, well designed, randomized trials are warranted.