Weekend effect in extracorporeal membrane oxygenation therapy initiation: a nationwide cohort study in South Korea

Background: Extracorporeal membrane oxygenation (ECMO) therapy requires close monitoring and optimal management after initiation. However, it remains unclear whether the day of the week of ECMO initiation affects patient outcomes. We aimed to investigate whether the initiation of ECMO therapy during a weekend was associated with increased mortality risk. Methods: We performed a population-level cohort study, based on health records obtained from the National Health Insurance Service database in South Korea. All critically ill adult patients who received ECMO therapy in the intensive care unit during 2005-2018 were enrolled. The primary endpoint was the 60-day mortality rate following ECMO therapy. Multivariable Cox regression was used for the analysis. Results: Data from a total of 21,129 ECMO patients were included in the analysis, of whom 12,825 (60.7%) died within 60 days. There were 4,647 (22.0%) patients who received ECMO therapy during a weekend (weekend group). Multivariable Cox regression revealed that the weekend group was at increased risk of 60-day mortality compared to the weekday group (hazard ratio: 1.05, 95% confidence interval: 1.01 to 1.09; P=0.025). In the sensitivity analysis, ECMO patients whose therapy started on a Saturday were at higher risk of 60-day mortality (hazard ratio relative to those whose therapy started on a Wednesday: 1.11, 95% confidence interval: 1.04-1.19; P=0.003). However, starting ECMO therapy on other weekdays (Thursday, Friday, Sunday, Monday, or Tuesday) did not affect mortality outcomes (P>0.05). Conclusions: ECMO therapy initiated during a weekend was associated with a slightly increased risk of 60-day mortality compared to that associated with ECMO therapy initiated on a weekday. This association was more evident in patients who received ECMO therapy that started on a Saturday. Further studies are needed to confirm these findings.