Is there a 'weekend effect' on mortality among hospitalised patients in an internal medicine ward? A retrospective study.

BACKGROUND: Previous studies demonstrated a 'weekend effect' and a 'night effect' of increased mortality among patients admitted during weekends or night shifts, presumably due to understaffing. AIMS: To examine whether death during hospitalisation follows a similar effect regardless of admission time. METHODS: A retrospective cohort study among deceased patients hospitalised in the internal medicine wing of a tertiary medical centre in Israel, between 2019 and 2020. Demographic and medical data were retrieved from electronic medical charts. Causes of death were specifically categorised. We applied statistical models to test for differences in mortality using incidence rate ratio (IRR) according to the day, time and cause of death. RESULTS: One thousand, two hundred and seventy-eight deceased patients were included. All-cause mortality was similar between weekends and weekdays. When sepsis was the cause of death, higher IRR were demonstrated on Fridays in comparison with weekdays (IRR 1.4; 95% confidence interval (CI) 1.1-1.9; P < 0.05). Other causes of death were not consistent with a 'weekend effect'. Mortality during night shifts was higher in comparison with the afternoon (IRR 1.5; 95% CI 1.3-4.7) and similar to the morning (IRR 1; 95% CI 0.9-1.2). CONCLUSION: Our study did not find a pattern of 'weekend effect' or 'night effect' on all-cause mortality among hospitalised patients in internal medicine wards. Our findings suggest that perhaps specifically death from sepsis, and not all-cause mortality, can be used as a surrogate for the measurement of understaffing or quality of care in the internal ward.