title: Weekly variation in health-care quality by day and time of admission: a nationwide, registry-based, prospective cohort study of acute stroke care.
abstract: Studies in many health systems have shown evidence of poorer quality health care for patients admitted on weekends or overnight than for those admitted during the week (the so-called weekend effect). We postulated that variation in quality was dependent on not only day, but also time, of admission, and aimed to describe the pattern and magnitude of variation in the quality of acute stroke care across the entire week.
  
  
  
  We did this nationwide, registry-based, prospective cohort study using data from the Sentinel Stroke National Audit Programme. We included all adult patients (aged >16 years) admitted to hospital with acute stroke (ischaemic or primary intracerebral haemorrhage) in England and Wales between April 1, 2013, and March 31, 2014. Our outcome measure was 30 day post-admission survival. We estimated adjusted odds ratios for 13 indicators of acute stroke-care quality by fitting multilevel multivariable regression models across 42 4-h time periods per week.
  
  
  
  The study cohort comprised 74,307 patients with acute stroke admitted to 199 hospitals. Care quality varied across the entire week, not only between weekends and weekdays, with different quality measures showing different patterns and magnitudes of temporal variation. We identified four patterns of variation: a diurnal pattern (thrombolysis, brain scan within 12 h, brain scan within 1 h, dysphagia screening), a day of the week pattern (stroke physician assessment, nurse assessment, physiotherapy, occupational therapy, and assessment of communication and swallowing by a speech and language therapist), an off-hours pattern (door-to-needle time for thrombolysis), and a flow pattern whereby quality changed sequentially across days (stroke-unit admission within 4 h). The largest magnitude of variation was for door-to-needle time within 60 min (range in quality 35-66% [16/46-232/350]; coefficient of variation 18·2). There was no difference in 30 day survival between weekends and weekdays (adjusted odds ratio 1·03, 95% CI 0·95-1·13), but patients admitted overnight on weekdays had lower odds of survival (0·90, 0·82-0·99).
  
  
  
  The weekend effect is a simplification, and just one of several patterns of weekly variation occurring in the quality of stroke care. Weekly variation should be further investigated in other health-care settings, and quality improvement should focus on reducing temporal variation in quality and not only the weekend effect.
  
  
  
  None.
authors.affiliation: Farr Institute of Health Informatics Research, University College London, London, UK. Electronic address: benjamin.bray@kcl.ac.uk.
authors.forename: Benjamin D
authors.initials: BD
authors.lastname: Bray
authors.affiliation: St George's NHS Foundation Trust, London, UK.
authors.forename: Geoffrey C
authors.initials: GC
authors.lastname: Cloud
authors.affiliation: Royal Devon and Exeter NHS Foundation Trust, Exeter, UK.
authors.forename: Martin A
authors.initials: MA
authors.lastname: James
authors.affiliation: Farr Institute of Health Informatics Research, University College London, London, UK.
authors.forename: Harry
authors.initials: H
authors.lastname: Hemingway
authors.affiliation: Royal College of Physicians, London, UK.
authors.forename: Lizz
authors.initials: L
authors.lastname: Paley
authors.affiliation: Clinical Effectiveness and Evaluation Unit, London, UK.
authors.forename: Kevin
authors.initials: K
authors.lastname: Stewart
authors.affiliation: Manchester Academic Health Sciences Centre, University of Manchester, Manchester, UK.
authors.forename: Pippa J
authors.initials: PJ
authors.lastname: Tyrrell
authors.affiliation: Division of Health and Social Care Research, King's College London, London, UK.
authors.forename: Charles D A
authors.initials: CD
authors.lastname: Wolfe
authors.affiliation: Division of Health and Social Care Research, King's College London, London, UK.
authors.forename: Anthony G
authors.initials: AG
authors.lastname: Rudd
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000000981:diagnostic imaging / Q000473:pathology; D015331:Cohort Studies; D003680:Deglutition Disorders / Q000175:diagnosis; D004739:England; D005260:Female; D054625:Healthcare Disparities / Q000706:statistics & numerical data*; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008403:Mass Screening; D008485:Medical Audit; D009788:Occupational Therapy / Q000706:statistics & numerical data*; D026741:Physical Therapy Modalities / Q000706:statistics & numerical data*; D011446:Prospective Studies; D011787:Quality of Health Care / Q000706:statistics & numerical data*; D011859:Radiography; D012042:Registries; D013066:Speech-Language Pathology / Q000706:statistics & numerical data; D020521:Stroke / Q000175:diagnosis / Q000401:mortality / Q000628:therapy*; D015996:Survival Rate; D015912:Thrombolytic Therapy / Q000706:statistics & numerical data*; D013997:Time Factors; D014852:Wales