Comparison of outcome in stroke patients admitted during working hours vs. off-hours; a single-center cohort study

Introduction: We aimed to disprove an in-hospital off-hour effect in stroke patients by adjusting for disease severity and poor prognostic findings on imaging. Patients and methods: Our study included 5378 patients from a single center prospective stroke registry of a large teaching hospital in the Netherlands, admitted between January 2003 and June 2015. Patients were categorized by admission time, off-hours (OH) or working hours (WH). The in-hospital mortality, 7-day mortality, unfavorable functional outcome (modified Rankin scale > 2) and discharge to home were analyzed. Results were adjusted for age, sex, stroke severity (NIHSS score) and unfavorable findings on imaging of the brain (midline shift and dense vessel sign). Results: Overall, 2796 patients (52%) were admitted during OH, which had a higher NIHSS score [3 (IQR 2–8) vs. 3 (IQR 2–6): p < 0.01] and had more often a dense vessel sign at admission (7.9% vs. 5.4%: p < 0.01). There was no difference in mortality between the OH-group and WH-group (6.2% vs. 6.0%; p = 0.87). The adjusted hazard ratio of in-hospital mortality during OH was 0.87 (95% CI: 0.70–1.08). Analysis of 7-day mortality showed similar results. Unadjusted, the OH-group had an unfavorable outcome [OR: 1.14 (95% CI: 1.02–1.27)] and could less frequently be discharged to home [OR: 1.16 (95% CI: 1.04–1.29)], which was no longer present after adjustment. Discussion and conclusions: The overall outcome of stroke patients admitted to a large Dutch teaching hospital is not influenced by time of admission. When studying OH effects, adjustment for disease severity and poor prognostic findings on imaging is crucial before drawing conclusions on staffing and material.