Winter pressures

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Winter pressures (winter crisis) is the health service jargon for the seasonal pressure on services from illness presentations in winter. Winter peak in overall or disease-specific hospital admissions has been reported in many countries, such as Australia, Bangladesh, Canada, Denmark, Israel, Japan, New Zealand, United Kingdom and United States. Common respiratory viruses are the main cause, and as well as an increased incidence of respiratory tract illness, conditions such as myocardial infarction, pulmonary embolism and stroke also increase as well as direct cold related presentations such as trauma or hypothermia. Some of the cerebrovascular disease presentations are now known to be associated with prior viral illness such as influenza or respiratory syncytial virus rather than just say the effects of vasoconstriction[1]. Much of the health systems burden results from longer hospitalisation rather than an increased admission rate. There are important epidemiological associations such as age and socioeconomic deprivation. The disease profile is different with winter admissions to hospital being more commonly due to chronic obstructive disease, pneumonia, epilepsy/seizures and congestive heart failure than in the other seasons of the year[2]. In Ireland patients admitted in the winter have an approximate 17% increased risk of an in-hospital death by 30 days. Studies from USA suggest that issues such as the skilled nurse number/patient being lower in winter contributes to this adverse outcome[3].

Implications with regard to health system surge capacity

These issues can be modelled[4]. However systems that train enough skilled clinical staff and provide enough infrastructure to allow the average annual demand of 85% bed occupancy necessary to in most health economies to cope with such seasonal demand without impacting on wider patient outcomes may be not resourced to do this. There is fair evidence that restrictions on non-urgent hospital utilization and hospital transfers may be a safe public health strategy to employ to control nosocomial outbreaks or provide hospital surge capacity for up to several months, in large, well-developed healthcare systems with good availability of community-based care[5].

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The rest of this article is biased towards the situation in the UK; however it describes a phenomena common to all emergency health care provision

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NHS England is unique in UK in providing an annual winter pressures report to parliament[6].

LogoKeyPointsBox.pngExcessive winter mortality can be improved at the macro level by[7]:
  • Improved protection from the cold indoors
  • Increased public spending on health care
  • More equitable income distribution

It is not significantly associated with:

  • The number of hospital beds (per 1000 population)
  • The number of GPs (per 1000 population)

The Winter crisis where emergency healthcare demand exceeds resources available in secondary care, while perceived as therefore a secondary care problem, increasingly it is recognised as primarily being caused by poor whole systems design, management and resourcing. Indeed the epidemiology of winter excessive mortality reveals that interventions such as improving housing stock and winter heating are extremely important[7]. Typically this may be manifest by excessive waits for treatment in Accident & Emergency departments, usually around the Christmas holiday break. The importance of holidays is emphasised by similar Easter crisis in Christian societies. Often political or cultural will does not exist to design out of the system the root causes of such crisis. Indeed it is likely political based redesign will create unintended consequences or predictable consequences such as impact on workforce morale.

Possible interventions

The traditional intervention has been to match health care resource to surge demand. Modelling suggests that for winter pressures the number of say acute hospital beds, or other emergency care parameters such as number of ambulances should be based on about 115% of that required for optimal annual efficiency. Winter crisis will happen several times yearly in a healthcare system running at an average of 90% acute bed occupancy, but only every few years at 85% acute bed occupancy.

At the macro level if the gaol is say to reduce the number of acute hospital beds these interventions appear to be effective[7]:

  • Improved protection from the cold indoors
  • Increased public spending on health care
  • More equitable income distribution


Both the public and healthcare staff can be very confused over the cause of such crises. They are not inevitable if the health and social care system has been well designed, resourced and managed. Most winter demand is very predictable as are the consequences of not having sufficient bed capacity. Bed capacity can be misunderstood as it is often seen as a flow of patient into and out of a classical reservoir of beds rather than a quantum reservoir problem. Indeed the multiple outlet pathways also create quantum issues which manifest chaos theory effects, the fewer patients who follow a pathway. It is even possible to design for a influenza outbreak, although a completely new illness such as SARS is much more problematical. They are not simply caused by excessive demand, as it is possible to have predictable demand causing a crisis due to inadequate bed base and discharge efficiency. For example in the absence of an unpredicted major infection outbreak in the winter of 2014/15 the English NHS had a winter crisis due to inadequate secondary care bed base and inadequate community care resources[8]. The most effective way of preventing such "winter crisis" for any given configuration of whole system care is to ensure that all significant care pools are resourced for a responsive occupancy defined by predictable demand. This usually fails to be created because of these factors:

  1. Poor management
    • Ultimately in a system as complicated as the NHS and subject to political whim with the law of unintended consequences this is usually at Government level. Local crises due to poor management are able to be coped with if good whole systems management has planned for the bad/corrupt and fraudulent creating local inefficiencies
    • Poor understanding of relevant information
      • Some have progressed little from Hippocrates observation that mortality is higher in cooler than in warmer months[9]. The illnesses presenting at greater frequency in winter are not just infections and the increase of about a third in population mortality is not just due to them which has implications for resource planning[10]. It has long been known that myocardial infarction[11] and stroke have apparently significantly increased incidence in Winter (by about a third) although much of this is artifact due to coding, diagnostic failings and greater morbidity due to say complicating infection or the actual associations with external temperature and stress events[12]. Morbidity increases seasonally so there is a greater institutionalisation rate in winter[13].
      • Planning is unlikely to assume that norovirus in the community closes care home beds to admission and stops care staff from caring for a patient load as no-one talks to occupational health about care worker seasonal sickness rates or correlates data of sickness impact
      • Perceived as an input problem. This is because the full A&E/emergency room is easy to ascertain and count, while the failure to train and employ enough staff for peak demand for convalescence at home is harder to quantify
      • It is known that a discharge plan tailored to the individual patient probably brings about a small reduction in hospital length of stay and reduces the risk of readmission to hospital at three months follow-up for older people with a medical condition[14]
    • Investment decisions
      • For example underinvestment by a government in social care will create a winter crisis
      • Cost of capacity only used for a few weeks of the year has opportunity costs elsewhere
        • Therefore there is a general drive to close expensive acute beds at times of financial pressure whatever peak demand and national statistics in England show this issue well with total acute bed pool falling by 1,100 fewer beds available between 2016/17 and 2017/18 (mitigated by reduced discharge delays, although a smaller reservoir copes less well with any flood that overwhelms the size of the downstream channel)[6]
      • Manpower planning
        • For example underinvestment in nurse training
        • Contracts that allow annual leave at times of peak activity
        • Workforce burnout/retirement not being allowed for
    • Inadequate design
      • Appropriate reward for the system roles necessary.
        • For example if disincentives exist to undertaking the extra activity necessary in a winter crisis it does not happen. In the NHS in England extra activity can have a tariff disincentive or in 2014 community beds were subsidised but without adequate notice to build and recruit to the subsidised capacity. Opening of empty wards that did exist was heavily discouraged.
        • Care package staff paid more for not taking leave at Christmas
  2. The financial cost
    • Overtime and other payments
    • Capacity in one part of the system to deal with the winter crisis precipitated by carers leave at Christmas could be unused for most of rest of year if for example training programs were not planned around periods of low demand
    • Health care system expenditure in those over 65 years old appears to increase by a third in Winter compared to summer[13]
  3. The investment time scale
    • This is usually 5 to 10 years due to time taken to train/redeploy manpower and build new plant or infrastructure
  4. System design
    • Factors such as school holidays, European working time directive, failure to promote and develop responsive care at home, training curriculum inadequacy, work force characteristics, job demarcation, poor communication

Excess Winter Mortality

The factors that produce winter pressures are also likely to be similar to those that result in excess winter mortality. In England and Wales since winter 1950/51 this statistic has had a general downwards trend with a major reduction in population burden until winter 2014/15. Such reversal of long term trend was not seen in all countries in Europe but was seen in the USA and has been postulated to be associated with changes in economic and social policy since 2008.
Absolute numbers of excess winter mortality England & Wales from winter 1950/1951 to winter 2016/2017. The variation year to year is mainly driven by variables such as circulating respiratory infections and external temperature. The long term trends are related to improvements in housing stock, social policy and public health policies with for example population level interventions that reduced air pollution, allowed more effective home central heating and influenza vaccination all being significant.[7] Accordingly deterioration in the statistic can be politically controversial.


  1. Blackburn RM, Zhao H, Pebody R, Hayward AC, Warren-Gash C. Laboratory-confirmed respiratory infections as predictors of hospital admission for myocardial infarction and stroke: time-series analysis of English data for 2004-2015. Clin Infect Dis. 2018 Jan 6. doi: 10.1093/cid/cix1144
  2. Callaly E, Mikulich O, Silke B. Increased winter mortality: the effect of season, temperature and deprivation in the acutely ill medical patient. Eur J Intern Med. 2013 Sep;24(6):546-51.doi: 10.1016/j.ejim.2013.02.004
  3. He J1, Staggs VS, Bergquist-Beringer S, Dunton N. Nurse staffing and patient outcomes: a longitudinal study on trend and seasonality. BMC Nurs. 2016 Oct 14;15:60
  4. Walker NJ, Van Woerden HC, Kiparoglou V, Yang Y. Identifying seasonal and temporal trends in the pressures experienced by hospitals related to unscheduled care. BMC Health Serv Res. 2016 Jul 26;16:307.doi: 10.1186/s12913-016-1555-7.
  5. Stukel TA, Schull MJ, Guttmann A, Alter DA, Li P, Vermeulen MJ, Manuel DG, Zwarenstein M. Health impact of hospital restrictions on seriously ill hospitalized patients: lessons from the Toronto SARS outbreak. Med Care. 2008 Sep;46(9):991-7doi: 10.1097/MLR.0b013e3181792525
  6. a b NHS Winter Pressures in England, 2017/18
  7. a b c d Healy JD. Excess winter mortality in Europe: a cross country analysis identifying key risk factors. Journal of epidemiology and community health. 2003 Oct; 57(10):784-789.(Print) (Link to article – subscription may be required.)
  8. The A&E winter crisis: lessons from last year Nuffield foundation December 2015
  9. Chadwick J, Mann WN, Lloyd GER Hippocratic writings. London, England: Penguin Books. (1983) 380 p
  10. Kalkstein AJ. Regional similarities in seasonal mortality across the United States: an examination of 28 metropolitan statistical areas. PloS one. 2013 ; 8(5):e63971.(Electronic-Print) (Link to article – subscription may be required.)
  11. Kloner RA, Poole WK, Perritt RL. When throughout the year is coronary death most likely to occur? A 12-year population-based analysis of more than 220 000 cases. Circulation. 1999 Oct; 100(15):1630-1634.(Print) (Link to article – subscription may be required.)
  12. Rothwell PM, Wroe SJ, Slattery J, Warlow CP. Is stroke incidence related to season or temperature? The Oxfordshire Community Stroke Project. Lancet (London, England). 1996 Apr; 347(9006):934-936.(Print) (Link to article – subscription may be required.)
  13. a b Rolden HJ, Rohling JH, van Bodegom D, Westendorp RG. Seasonal Variation in Mortality, Medical Care Expenditure and Institutionalization in Older People: Evidence from a Dutch Cohort of Older Health Insurance Clients. PloS one. 2015; 10(11):e0143154.(Electronic-eCollection) (Link to article – subscription may be required.)
  14. Gonçalves-Bradley DC, Lannin NA, Clemson LM, Cameron ID, Shepperd S. Discharge planning from hospital. The Cochrane database of systematic reviews. 2016; 1:CD000313.(Epub) (Link to article – subscription may be required.)