Is seniority of emergency physician associated with the weekend mortality effect? An exploratory analysis of electronic health records in the UK

Objective Admission to hospital over a weekend is associated with increased mortality, but the underlying causes of the weekend effect are poorly understood. We explore to what extent differences in emergency department admission and discharge processes, severity of illness, and the seniority of the treating physician explain the weekend effect. Methods We analyzed linked emergency department attendances to hospital admissions to Cambridge University Hospital over a seven-year period from January 1, 2007 to December 31, 2013 with 30-day in-hospital death as the primary outcome and discharge as a competing risk. The primary exposure was day of the week of arrival. Sub-distribution hazards models controlled for multiple confounders, including physician seniority, calendar year, mode of arrival, triage category, referral from general practice, sex, arrival time, prior attendances and admissions, diagnosis group, and age. Results 229,401 patients made 424,845 emergency department attendances, of which 158,396 (37.3%) were admitted to the hospital. The case mix of admitted patients was more ill at weekends: 2,530 (6.4%) admitted at a weekend required immediate resuscitation compared to 6,450 (5.4%) on a weekday (p