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

Abstract

Increased mortality related to differences in delivery of weekend clinical care is the subject of much debate. We compared mortality following detection of acute kidney injury (AKI) on week and weekend days across community and hospital settings. A prospective national cohort study, with AKI identified using the Welsh National electronic AKI reporting system. Data were collected on outcome for all cases of adult AKI in Wales between 1 November 2013 and 31 January 2017. There were a total of 107298 episodes. Weekday detection of AKI was associated with 28.8% (26439); 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% (10356) 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). 'Weekend effect' in AKI relates to access to in-patient care for patients presenting predominantly to hospital emergency departments with AKI at the weekend.