Do hospitals have a higher mortality rate on weekend admissions? An observational study to analyse weekend effect on urgent admissions to hospitals in Catalonia

BACKGROUND: ‘Weekend effect’ is a term used to describe the increased mortality associated with weekend emergency admissions to hospital, in contrast with admission on weekdays. The objective of the present study is to determine whether the weekend effect is present in hospitals in Catalonia. METHODS: We analysed all urgent admissions in Catalonia in 2018, for a group of pathologies. Two groups were defined (those admitted on a weekday and those admitted on a weekend). We obtained mortality at 3, 7, 15 and 30 days, and applied a proportions test to both groups. Additionally, we used Cox’s regression for mortality at 30 days, using the admission on a weekend as the exposition, adjusting by socioeconomic and clinical variables. We used the hospital discharge database and the Central Registry of the Insured Population. RESULTS: 72 427 admissions for the selected pathologies during 2018 were found. No statistically significant differences in mortality at 30 days (p=0.524) or at 15 days (p=0.119) according to the day of admission were observed. However, significant differences were found in mortality at 7 days (p=0.025) and at 3 days (p=0.002). The hazard rate associated with the weekend was 1.13 (95% CI: 1.04 to 1.23). By contrast, the adjusted HR of the weekend interaction with time was 0.99 (95% CI: 0.99 to 1.00). CONCLUSIONS: There is a weekend effect, but it is not constant in time. This could suggest the existence of dysfunctions in the quality of care during the weekend.