key: cord-1043691-u1552jje authors: Aly, Hany title: A closer look at the weekend effect and COVID-19 mortalities date: 2021-02-04 journal: Journal of neonatal-perinatal medicine DOI: 10.3233/npm-200636 sha: 1d7ed3e1ffab6ce075078dd1ed617454b849d9fb doc_id: 1043691 cord_uid: u1552jje nan this effect is unclear, the weekend effect on mortality is apparent across a range of disease presentations [5] . A 2017 meta-analyses of 97 studies showed that patients admitted on the weekends had a significantly higher overall mortality (relative risk, 1.19; 95% confidence interval, 1.14-1.23) [6] . With regard to subgroup analyses, patients admitted on the weekends consistently had higher mortality than those admitted during the week, regardless of the levels of weekend/weekday differences in staffing, procedure rates and delays, and illness severity [6] . Contradictory studies such as that by Freemantle et al., showed that the likelihood of death by all causes is less on a weekend day than on a mid-week day [7] . Research continues on this matter to better understand the reasons and implications of the weekend effect and how caregivers may address them. To determine the extent to which the weekend effect is associated with COVID-19 mortalities, we recently surveyed COVID-19 deaths within the U.S. using data presented by the Worldometer [2] . We specifically assessed the difference between deaths that occurred Monday-Friday (weekdays) versus those that occurred on Saturday and Sunday (weekend) from March through October. Examination of COVID-19 associated deaths in the U.S. showed significantly less deaths on Saturday and Sunday, compared to deaths on weekdays (Z = 3.527, p = 0.0004) (Fig. 1) . While we weren't able to determine factors such as illness severity at time of admission and staffing level differences during the 8 H. Aly / A closer look at the weekend effect week versus on the weekend, this is still an interesting finding and something that should be investigated further. If decreased COVID-19 mortality was related to reporting delays during weekends, we should have noticed surges in mortality on Mondays. However, this is not true, as mortality on Mondays was not any higher than other days of the week. Interestingly, the "weekend effect" we report for COVID-19 in the US, does not exist in other countries such Germany, Italy, Iran and Turkey. During a global pandemic, such as what we are experiencing with COVID-19, taking a closer look at mortality rates and understanding the reasons for fluctuations allows caregivers to assess their practices to provide the best outcomes for patients. Further studies, with detailed clinical data are urgently needed to investigate the drivers of and causes for the risk of death on weekdays/weekends from COVID-19. An interactive web-based dashboard to track COVID-19 in real time COVID-19 Coronavirus pandemic People who are at higher risk for severe illness Genomic characterization and epidemiology of 2019 novel coronavirus: Implications for virus origins and receptor binding The enigma of the weekend effect The weekend effect in hospitalized patients: A meta-analysis Weekend hospitalization and additional risk of death: An analysis of inpatient data