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Exploring the characteristics, acuity and management of adult ED patients at night-time
  1. Rebecca Simpson,
  2. Susan Croft,
  3. Colin O’Keeffe,
  4. Richard Jacques,
  5. Tony Stone,
  6. Nisar Ahmed,
  7. Suzanne M Mason
  1. School of Health and Related Research, University of Sheffield, Sheffield, UK
  1. Correspondence to Dr Rebecca Simpson, School of Health and Related Research, University of Sheffield, Sheffield S1 4DA, UK; r.simpson{at}


Objectives ED care is required for acutely unwell and injured patients 24 hours a day, 7 days a week. The aim of this study was to compare characteristics and activity of type 1 ED attendances according to whether their time of arrival was during the day (08:00–18:00) or at night (18:00–08:00).

Methods Hospital Episode Statistics (HES) data from NHS Digital for all A&E and admitted patient care activity provided by all acute (not mental health or primary care) NHS hospital trusts in Yorkshire and Humber (1 April 2011 to 31 March 2014) for adult patients were analysed. Adjusted linear and logistic regression was used to model the data.

Results Adjusted regression analysis results show that patients who attended ED at night waited an extra 18.76 (95% CI 18.62 to 18.89) min to be seen by a clinician. They also spent an additional 13.64 (95% CI 13.47 to 13.81) min total in ED. Patients who attended at night were OR 2.20 (95% CI 2.17 to 2.23) times more likely to leave without being seen. They were also OR 1.26 (95% CI 1.25 to 1.27) times more likely to re-attend the ED and were OR 1.20 (95% CI 1.19 to 1.21) times more likely to present with non-urgent conditions. Overnight patients were more likely to be admitted to hospital, OR 1.09 (95% CI 1.09 to 1.10) times, however, those admitted were more likely to have a short-stay admission.

Conclusion There is an ‘overnight effect’ of patients attending EDs. Patients wait longer, leave without being seen, attend with non-urgent problems and are more likely to be admitted for a short stay. Further work is required to identify the potential underlying causes of these differences.

  • emergency medicine
  • emergency and urgent care
  • overnight effect
  • out of hours effect
  • emergency department attendances

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  • Contributors SMM, CO’K and RJ conceived the study. NA performed the background searches. Data linkage was performed by TS and statistical analysis of results by RS and RJ. Interpretation of data was performed by RS, SMM, SC, CO’K and RJ. RS and SC drafted the initial manuscript and all authors contributed to its revision.

  • Funding The research was funded by the NIHR CLAHRC Yorkshire and Humber,

  • Disclaimer The views expressed are those of the author(s), and not necessarily those of the NHS, the NIHR or the Department of Health.

  • Competing interests The authors report grants from NIHR, inside and outside the submitted work.

  • Ethics approval Ethical approval was obtained from the National Health Service Health Research Authority: South West Exeter (14/SW/1014).

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement Data may be obtained from a third party and are not publicly available.

  • Author note The Out of Hours Effect. Exploring patterns of ED attendance and admission during weekdays, weekends and night-time. HSRUK Conference 2018. An overnight effect rather than a weekend effect? Exploring patterns of ED attendances during weekdays, weekends and night-time. EUSEM 2018.

  • Patient consent for publication Not required.

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