The phenomenon of the “weekend effect”, whereby patient outcomes are significantly worse for those admitted to hospital on the weekend as compared to weekdays, is well-documented in systematic reviews and meta-analyses in the literature. We sought to assess the effect of the time of a patient’s admission on outcomes across an entire cardiology admissions cohort and explore other factors that have been previously identified or proposed to influence these outcomes, including admissions out-of-hours, and patient transfers from other facilities.

We conducted a retrospective cohort study involving cardiology admissions at a large tertiary referral centre across a 6-year period from 1 January 2012 to 31 December 2017. Outcomes were in-hospital, 30-day and 1-year mortality rates as well as length-of-stay, and readmission rate. 14,078 patients admitted under a cardiologist across the 6-year period were identified, with 3,029 elective patients excluded. Patients were stratified into weekday (n=8,951) or weekend (n=2,098) categories.

In-hospital mortality for weekend admissions was noted to be significantly higher compared to weekday admissions (adj OR 1.78, 95% CI 1.40–2.28; p<0.001). Mortality for weekend admissions was also higher at 30-days (adj OR 1.74, 95% CI 1.39–2.17; p<0.001) and at 1-year (adj OR 1.33 95% CI 1.14–1.55; p<0.001). Adjusted for diagnosis, there was a significant increase in in-hospital, 30-day and 1-year mortality seen only for weekend admissions with the final diagnosis of acute myocardial infarction.

We have identified an association between weekend admissions and higher in-hospital, 30-day and 1-year mortality for the final diagnosis of acute myocardial infarction in our cardiology admissions data over an extended period of time, although confounders cannot be completely discounted. Any steps to reduce the weekend effect need to move to a system where weekend practices are not substantially different to a usual business day. The question of whether changes in organisation practice and the increased costs incurred would reduce mortality in this high-risk group needs to be addressed by further directed research.