NHS trusts and frontline staff worked tirelessly to maintain and improve performance in the face of extremely challenging circumstances last winter. Although the NHS treated record numbers of patients over the winter, the increases in demand, from an ageing and more frail population, outstripped the available capacity.

With workforce shortages and severe funding pressures, it was not possible to increase capacity and, as a result, the NHS came under sustained pressure for a number of weeks.  This manifested itself as a drop in performance and an increased risk to patients’ safety with deteriorating performance against the 95% A&E target, a spike in the number of ambulance diverts, and a significant increase in trolley waits.

This situation was amplified by insufficient capacity in all types of trust – acute hospitals, mental health, community and ambulance – and exacerbated by increasingly high levels of delayed transfers of care (DTOCs).

NHS performance between December 2016 – February 2017

Between December 2016 and February 2017:

  • Performance against the A&E four-hour waiting time target continued to fall, with an average of 86.3% of patients seen within four hours against the 95% standard, compared to an average of 89.1% in the same period last year. 

  • The number of times patients diverted to another A&E departments due to a lack of capacity almost doubled compared to last year.

  • The NHS had less than 85% bed occupancy on only three days in winter (The King's Fund 2017), despite this being well recognised as a safe limit (BMJ 1999) and a third of all trusts had bed occupancy rates of 100% on at least one day over winter. On one day in January, one in seven trusts reported that all their acute beds were full, and for nearly 4 out of 10, 98% of their beds were occupied (Nuffield Trust 2017).

  • In one week alone (2-8 January 2017), the NHS had over 31,000 escalation beds open to cope with winter demand, the equivalent of opening an additional eight hospitals.

  • Ambulances were unable to meet the target for response times for 999 calls in the face of increasing demand. For the three peak winter months Red 1 performance was an average of 67.5% and Red 2 performance was an average of 59.6%, both below the expected standard of 75%. 

If these trends continue into this coming winter, performance will deteriorate further, meaning more patients will wait longer to be seen, treated and discharged, and frontline staff will experience increasing pressures as they seek to deliver care in very challenging circumstances.

Delayed transfers of care are having a material impact on the NHS’s ability to manage winter pressures

Many of last winter’s problems were due to increased levels of DTOCs. The ability to move patients quickly and safely out of one setting and in to another is crucial to ensuring patients are treated in the right settings at the right time. Delays in transfers of care prevent this, and they have been increasing sharply in recent years.  Since the start of 2014/15, the DTOC rate has increased from 3.5% to 5.6% at the end of 2016/17 (our calculation of the delayed transfers of care rate is in line with NHS England: total delayed beds/total occupied beds). In 2016/17 almost 630,000 more bed days were lost compared to 2014/15, a 39% increase, the equivalent of three 550-bed hospitals being full of DTOCs for the entire year.

DTOCs place a number of constraints on trusts, reducing their ability to use beds and space flexibly, preventing the flow of patients through services, and impacting on the ability of trusts to provide the right quality of patient safety and experience.


Although the acute sector has the largest number of beds and, therefore, the highest number of delayed days in total, the DTOC rate is actually highest in community providers, peaking in January 2016 when, on average, 28.5% of beds were occupied by DTOCs. 

DTOCs place a number of constraints on trusts, reducing their ability to use beds and space flexibly, preventing the flow of patients through services, and impacting on the ability of trusts to provide the right quality of patient safety and experience.

Flexibility and bed occupancy

DTOCs can impact adversely on bed occupancy within the acute, community and mental health sectors as well as on ambulance transfers. NHS capacity across all these sectors is largely fixed in the immediate short term – it is usually impossible or very difficult to quickly increase capacity to meet short term spikes in demand.

For example, a lack of physical space, funding constraints and workforce shortages mean that increasing the number of beds or opening a new ward is often not a simple option. As one trust chief operating officer told us: “our walls are not elastic, and we are unable to simply flex capacity up or down”.

Patient flow

High bed occupancy and lack of space have a knock-on effect on patient flow. A certain proportion of beds needs to be free for patients to flow through the system. When space is very tight, trusts may be forced to resort to a one in, one out approach to admission and discharge. This causes queues and backlogs elsewhere, such as ambulance handovers, emergency admissions, and transfers to other NHS settings. The link between these factors is underpinned by research which shows that those trusts achieving the four-hour target have lower bed occupancy levels across their acute beds (Nuffield Trust, bed occupancy research).

Patient safety and patient experience

It is widely accepted that persistently large numbers of trolley and 12-hour waits are a good proxy for significantly elevated risk to patient safety and potential for significant harm (use of the word persistently is designed to distinguish between low numbers of such cases occurring infrequently and large numbers of such cases occurring frequently and over an extended period). They also mean a much worse experience for patients – often one that no patient would want to have or any NHS staff member would want to provide.The same applies to persistently large numbers of long ambulance waits.

Wider constraints

Acute hospital bed occupancy is the most well-recognised measure of capacity in the NHS. However, focusing solely on acute hospital beds masks capacity constraints in other parts of the system, including mental health, community and ambulance services. Having the appropriate resources in NHS 111 and 999 centres; the right number of community step down facilities; enough social care packages; and sufficient mental health out reach and liaison teams, all impact on a system’s overall capacity to meet patient demand. Insufficient capacity in any part of this system means that providers may not be able to provide care in a timely way. This can affect patient safety and patients’ experience of care, and then cause knock-ons to the other parts of the system.

Last winter was extremely challenging. Although the NHS as a whole made it through, some local healthcare systems did ‘fall over’ and those that managed had to rely disproportionately on discretionary staff effort which is unsustainable in the medium or long term.

There has been widespread agreement across the NHS that the impact on staff and the risk to patient safety is not acceptable. This winter, where the weather has not been bad and the levels of winter flu and norovirus have been low, is a timely warning.