Adding a new dimension to the weekend effect: An analysis of a national data set of electronic AKI alerts

Abstract

Background: Increased mortality related to differences in delivery of weekend clinical care is the subject of much debate. Aim: We compared mortality following detection of acute kidney injury (AKI) on week and weekend days across community and hospital settings. Design: A prospective national cohort study, with AKI identified using the Welsh National electronic AKI reporting system. Methods: Data were collected on outcome for all cases of adult AKI in Wales between 1 November 2013 and 31 January 2017. Results: There were a total of 107 298 episodes. Weekday detection of AKI was associated with 28.8% (26 439); 90-day mortality compared to 90-day mortality of 31.9% (4551) for AKI detected on weekdays (RR: 1.11, 95% CI: 1.08-1.14, P<0.001, HR: 1.16 95% CI: 1.12-1.20, P<0.001). There was no 'weekend effect' for mortality associated with hospital-acquired AKI. Weekday detection of community-acquired AKI (CA-AKI) was associated with a 22.6% (10 356) mortality compared with weekend detection of CA-AKI, which was associated with a 28.6% (1619) mortality (RR: 1.26, 95% CI: 1.21-1.32, P<0.001, HR: 1.34, 95%CI: 1.28-1.42, P<0.001). The excess mortality in weekend CA-AKI was driven by CA-AKI detected at the weekend that was not admitted to hospital compared with CA-AKI detected on weekdays which was admitted to hospital (34.5% vs. 19.1%, RR: 1.8, 95% CI: 1.69-1.91, P<0.001, HR: 2.03, 95% CI: 1.88-2.19, P<0.001). Conclusion: 'Weekend effect' in AKI relates to access to in-patient care for patients presenting predominantly to hospital emergency departments with AKI at the weekend.