The NHS waiting list: when will it peak?

Introduction

The waiting list for elective care in England has now reached 7.7 million. Behind these numbers are people anxious for a diagnosis, patients in avoidable pain and lives put on hold. Reducing the number waiting is a top priority for government and the health service alike. This long read analyses the prospects of reducing the waiting list by the end of 2024 and assesses the impact of further industrial action on the size of the waiting list. It incorporates an interactive waiting list calculator that will allow you to explore what could happen to the waiting list in a range of different plausible scenarios. 

Waiting lists have been a fact of life since the inception of the NHS, with statistics on the numbers of patients waiting for routine hospital treatment dating back to 1949. All health systems ration access to services, but the NHS’s founding principle that care is largely free at the point of use means how long we wait – rather than how much we pay – has become emblematic of the overall state of the health service. Reducing hospital waiting times consistently features among the public’s top priorities for the NHS, with successive governments setting targets for how long patients should wait and the 18-week referral-to-treatment standard being made a right in the NHS Constitution. 

The NHS consistently met the 18-week standard from 2008 to 2015. But a combination of growing demand, funding constraints and growing staff shortages mean the standard has not been met since February 2016. At the same time, the number of patients on the waiting list has steadily increased, passing 3.0 million in February 2014 and, on the eve of the COVID-19 pandemic in February 2020, had grown to almost 4.6 million. The need to postpone large volumes of routine care to free up space for patients acutely unwell with COVID-19 saw the waiting list swell to 6.2 million by February 2022, when the remaining pandemic restrictions ended. Since then, the waiting list has continued to increase, as efforts to address the backlog have been hampered by the significant financial and operational pressures facing the NHS and, since November 2022, by industrial action.

Against this backdrop, the Prime Minister, Rishi Sunak, pledged that ‘NHS waiting lists will fall and people will get the care they need more quickly’ in a speech on 4 January 2023. The pledge does not define how far the waiting list should fall or a timescale for achieving this, leaving considerable room for interpretation about how it will be met. This followed on from the publication of the elective care recovery plan by NHS England in February 2022, which includes an expectation that the waiting list would be falling by around March 2024.
 

A short history of the waiting list and waiting times

Over the past 10 years, the number of new referrals for diagnostic tests or treatment has exceeded the number of completed pathways (see Box 1). As a result, the total waiting list has consistently risen, with the exception of the first few months of the COVID-19 pandemic, as shown in Figure 1. The waiting list has tripled over the past 10 years and currently stands at 7.7 million. The number of pathways where people are waiting more than 18 weeks has risen even more quickly – from 162,000 in January 2013, 782,000 just before the pandemic, to 3.3 million in August 2023. 

There are three key measures of waiting times published by NHS England: 

• the proportion of people on the list who have been waiting 18 weeks or less, which is expected to be at least 92%
• the median time waiting time in weeks for those currently on the waiting list 
• the 92nd percentile time in weeks for those currently on the waiting list – this metric shows that 92% of people have been on the waiting list for fewer than the number of weeks reported in this measure, and conversely that 8% of people are waiting for longer than this.

While hospital activity has steadily increased post-pandemic, the NHS is only just returning to pre-pandemic levels of activity and waiting times against all three of these measures have steadily worsened. The most commonly used of the three metrics is the standard that 92% of patients should be treated within 18 weeks of referral. Figure 1 shows how the number patients waiting longer than 18 weeks grew steadily over time, then increased rapidly during the pandemic and has continued to grow since. In August 2023, only 58% of people on the waiting list had been waiting less than 18 weeks. Figure 2 looks at the other two measures. It shows that the median waiting time had almost doubled since before the pandemic to 14.5 weeks in August 2023. The 92nd percentile of waiting times shows that 8% of people currently waiting for treatment have been waiting more than 46.3 weeks, up from 24.7 weeks immediately before the pandemic.  

Since the rapid increase in long waits during the pandemic, there has been a particular focus on reducing these long waits. The elective care recovery plan set out an ambition that waits of longer than a year would be eliminated by March 2025 and included three key milestones on the way to achieving this: 

• ensuring that no one waits longer than 2 years by July 2022
• eliminating 18-month waits by April 2023 
• eliminating waits of more than a year by March 2025. 

In August 2022, NHS England announced that 2-year waits had been ‘virtually eliminated’. However, although significant progress has been made in reducing long waiting times, the target of eliminating 18-month waits was missed and achieving the targets to end waits of more than a year by March 2025 are likely to be challenging.  
 

Modelling the future size of the waiting list

Given the recent rapid increase in the waiting list, how might the waiting list change in the future? We have developed a model to assess what might happen to the size of the waiting list by the end of 2024. We project the current waiting list forward month-by-month by adding the projected new referrals to the list and subtracting projected completed pathways (as defined in Box 1). The number of completed pathways depends on NHS activity levels, which in turn depends on capacity, financial investment and productivity of the NHS. In a given month activity levels can also be disrupted by industrial action. There are a range of wider impacts that can also influence activity levels. Below we set out our analysis of each of these components, informing our projections and scenarios.

New referrals

To project new referrals we use the trend in new referrals per working day from May 2021 to July 2023. This is a longer period than we use for calculating the trend in completed pathways as new referrals are not expected to be impacted by strikes in hospital. Between May 2021 and July 2023, new referrals per working day increased by 5.0% per year. The number of referrals has recently exceeded their pre-pandemic level and are growing at a faster rate than before the pandemic. We use 5.0% as our base assumption for the growth in new referrals per working day between September 2023 and December 2024. 

Completed pathways

To project completed pathways we use the trend in completed pathways per working day from May 2021 to February 2023. We use data up until February 2023 to provide an indication of the growth rate in completed pathways per working day before the start of industrial action by hospital doctors. Based on this analysis, our base assumption is that completed pathways per working day continue to grow at a rate of 7.8% per year. Although the number of completed pathways per year is lower than before the pandemic, the rate of growth of completed pathways per working day is higher (Figure 3). In other words, the NHS is currently accelerating the rate of treatment at a faster rate than before the pandemic to get back to pre-pandemic levels of activity and reduce the waiting list.

Industrial action

Since November 2022, an unprecedented series of strikes have been held across the NHS. Hospital doctors, nurses, paramedics, radiographers and other staff groups have held industrial action on 52 days up until October 2023, resulting in more than 1.1 million procedures and outpatient appointments being postponed. In this analysis, we focus on the impact of walkouts by junior doctors and consultants because of the direct impact on the waiting list for consultant-led care. 

We project the impact of industrial action based on assumptions we have made about the number of months in which there could be strikes, and the number of rescheduled appointments and procedures within each strike month. We convert these rescheduled appointments and procedures into the expected number of pathways that would not be completed as a result. We assume that the number of rescheduled appointments and procedures will decrease over time (because evidence indicates that the strikes have fewer staff engaged in them over time - we have called this ‘strike intensity’ in our model) and that the total number of procedures and appointments that are rescheduled will be 95% of the number in the previous month. Since the start of industrial action by hospital doctors in March and up to and including strikes in October, we estimate that around 213,000 fewer pathways have been completed.  

Wider impacts

Industrial action has immediate, direct impacts on elective care activity through rescheduled appointments and procedures, which we have tried to quantify in our approach to projecting the waiting list. However, it also has other effects that may cause wider and longer-term impacts. These include: 

• annual leave being deferred to provide cover during the strikes – the effect of this is that activity levels will be lower in the future, when deferred leave is taken
• management attention being diverted to dealing with the strikes, including rescheduling appointments and organising cover, and away from activities that could increase hospital efficiency, elective care productivity and levels of activity
• extra costs arising from providing cover on strike days, as rates for staff cover are substantially higher than usual pay rates, and rearranging cancelled operations  
• loss of efficiency and productivity improvements – financial pressures also arise because there are fewer opportunities for management staff to make efficiency improvements and realise cost savings. 

The total cost of industrial action to the NHS is reported to be over £1.1bn up until the end of July. Around half of this is the additional cost of mitigating strike impacts, for example the overtime and agency costs of providing cover. The other half is the value of lost activity through rescheduled appointments and procedures. We have included estimates of lost activity in our waiting list projections by reducing the growth of completed pathways. 

Factors beyond industrial action could also affect the future growth in elective care activity. One is the growing financial pressures on the NHS which, on top of those arising from strikes, have been exacerbated by higher-than-expected inflation and meeting pay awards. There is increasing pressure for NHS hospital trusts to cut costs to avoid large financial deficits at the end of 2023/24 financial year; one way of doing this is by cutting back on planned elective care activity.  

Another factor is productivity. Although productivity is lower than before the pandemic, elective care activity has been growing at 7.8% a year, which is faster than it was growing than before the pandemic. However, it is unclear to what extent this growth can be maintained and productivity can fully recover. Evidence suggests a number of issues are contributing to low productivity including: lack of capital investment, high staff churn, the loss of experienced staff, low staff morale, insufficient numbers of hospital managers and insufficiently clear or simple targets and incentives that hospitals are expected to meet. These factors could all hamper recovery of previous levels of productivity. 

The impact of these factors is hard to estimate, but all will affect the levels of growth in completed pathways. This can be incorporated into our model by decreasing the growth in completed pathways by working day.

Limitations

Our model produces projections of the size of the waiting list based on certain assumptions. These are projections not predictions: they show what would happen if these assumptions hold. The choice of assumptions and their values are matters of judgement. In our base case our assumptions are based on past trends but, because the future is inherently uncertain, things may turn out differently. 

While we have accounted for a number of factors that influence the waiting list, there are other factors that we cannot account for. For example, while we have accounted for typical winter pressures, if there is a particularly bad winter that exacerbates pressures on the health service, there is likely to be a larger reduction in the level of elective care that can be delivered. Furthermore, another wave of COVID-19 may result in elective procedures being cancelled as more care and beds are required for those ill with COVID-19.

Another factor we have not accounted for is financial pressures that would require hospitals to reduce the number of elective treatments in order to avoid financial deficits. If this were to happen, waiting lists would be unlikely to plateau and begin to come down in 2024.

Further details of the data we have used and limitations of our analysis are available in a technical appendix. All our code can be found on GitHub.

What might happen to the waiting list?

Waiting list calculator

Use the interactive calculator to explore the future size of the waiting list, under different assumptions about the future growth in referrals, completed pathways and the number and intensity of future strikes.

Scenarios

To help assess when the waiting list is likely to fall, we examine four possible scenarios. These are illustrated in the interactive calculator. 

Scenario 1: Hospital activity growth stays the same and strikes stop

New referrals and completed pathways per working day continue to follow the existing trends at a growth rate of 5.0% and 7.8% per year per working day respectively. There is no further strike action beyond the joint strikes in October 2023. With no further strike action, the waiting list is expected to peak at just under 8 million in August 2024. The waiting list would then fall but is still projected to exceed 7.7 million by December 2024.

Scenario 2: Hospital activity growth stays the same and strikes continue

New referrals and completed pathways per working day continue to follow the existing trends at a growth rate of 5.0% and 7.8% per year respectively; both junior doctor and consultant strikes continue during 2024. Under this scenario, the waiting list would peak at over 8.1 million, in August 2024, 180,000 compared to scenario 1. The waiting list would then fall but is projected to be just under 8.0 million by the end of the year.

Scenario 3: Hospital activity growth decreases and strikes continue

Strikes continue as in scenario 2, but the underlying growth in completed pathways per working day reduces by a third, from 7.8% to 5.2%. There is no firm basis for this assumption and the scenario is included as an illustration of what could happen if the strikes continue and have an, as yet, unseen impact or activity is affected for other reasons. In this scenario growth in completed pathways is very close to the growth in referrals, so completed pathways remain below referrals and the waiting list continues to grow, reaching over 8.4 million by the end of 2024.

Scenario 4: Hospital activity growth increases significantly and strikes stop

There is no further strike action and additional productivity gains are made with the underlying growth in completed pathways per working day increasing by a third from 7.8% to 10.4%. Again, there is no firm basis for this assumption and this is included as an illustration of what could happen if the strikes stop and the NHS is able to significantly increase activity levels. In this scenario, the waiting list would peak in October 2023 and would be at just above 7.2 million by the end of 2024. 

If referrals and completed pathways continue to grow in line with recent trends, the waiting list would continue to rise until next summer, whether or not strike action continues, and then start to fall, as shown in scenarios 1 and 2.

If the future growth in completed pathways were to fall to 5.2%, as in scenario 3, as a result of the wider and long-term impacts of industrial action, a particularly bad winter, another wave of COVID-19, or financial pressures requiring cutbacks in elective care, new referrals would continue to exceed completed pathways and the waiting list would continue to grow over this projection period. Conversely, if strikes were to stop immediately and there was a significant increase in activity with completed pathways per working day increasing from the current trend of 7.8% to 10.4%, as shown in scenario 4, the waiting list would be just above 7.2 million by December 2024. Only under this scenario would the waiting list be at the same level it was at when the Prime Minister made his pledge. Even under this scenario, the expectation in the elective care recovery plan that it would be falling by around March 2024 will not be met.  

Ministers have been quick to blame strikes for the lack of progress in reducing the backlog. However, in November 2022, before the strikes began, the National Audit Office warned that there were ‘significant risks’ to the delivery of the elective recovery plan, finding that post-pandemic activity was lagging well below the trajectory needed to meet the ambitions it set out. 

Although our modelling suggests that the direct effect of industrial action will not have a significant impact on when the waiting list peaks, it does suggest it will affect the level of the peak and the size of the waiting list at the end of 2024. If strikes continue throughout 2023 and 2024, the projected waiting list in December 2024 would be around 300,000 higher compared with if they were to stop immediately.  

Conclusions

The waiting list has almost tripled over the past decade. It grew steadily between 2013 and 2019, grew sharply during the pandemic and has since continued to increase rapidly. The growing backlog of elective care cannot be attributed to the COVID-19 pandemic alone. Its roots lie in a decade of underinvestment in the NHS and other public services, an avoidable failure to address chronic staff shortages, lack of capital investment and the longstanding neglect of adult social care.

Reducing the waiting list for elective care has become the government’s top priority for the NHS since the end of the pandemic. Although progress has been made in reducing long waits for treatment, our analysis shows that if current trends were to continue, the waiting list would continue to grow before peaking in summer next year. Industrial action has slowed the efforts to reduce the waiting list and will continue to do so if further walkouts go ahead, and further costs mount. The strikes will continue to have wider impacts on patients through delayed care, as well as longer term impacts on productivity. 

Other factors that may affect the growth in elective care activity and the size of the waiting list over the coming months include pressures on NHS trust finances, which may lead to hospitals cutting back on planned activity, and the extent to which productivity can be improved given the long-term lack of capital investment and the state of the workforce. 

Eliminating the backlog and restoring waiting times to 18 weeks will be very challenging. But with effective policies and tools, supported by investment in the workforce and treatment capacity, history shows it is achievable. The NHS has previously delivered major reductions in waiting times for elective care, most recently the ambition to cut waits from ‘18 months to 18 weeks' that was set in 2004, met in 2008 and largely sustained until 2016. However, there are no quick fixes and focus will need to be sustained over several years.

The government needs to address the underlying problems facing the health service. Some positive steps have already been taken, including the NHS Long Term Workforce Plan to address the significant staff shortages, but improving NHS productivity requires broader action and investment. As well as training more staff, the NHS needs to do more to retain the skills and experience it already has. While successive governments have prioritised front-line staff, sustainably improving waiting times also requires high-quality operational management and analytical capability. Significant investment in the buildings, equipment, IT and digital infrastructure is also needed for staff to work effectively. Until these problems are addressed, patients will continue to face long waits for care that they need. These issues are avoidable.

Acknowledgements

We thank the many people who generously shared their knowledge with us during the write up of this piece. Thanks to Ellen Coughlan, Paul Chappell and Tatjana Marks for their support and insights. Special thanks to both Chris Beeley at the Strategy Unit, as well as Marc Brazzill at WPI Economics, who were able to help us with the interactive calculator at very short notice.