The NHS needs to ramp up treatment volumes if waiting lists are to start falling any time soon

NHS waiting lists have continued to rise this year, and in September 2022 there were 7.1 million incomplete waiting list pathways in England[1] . This is 60% higher than prior to the pandemic in February 2020 (4.4 million), and 17% higher than at the end of 2021 (6.1 million). Tackling this backlog of care is a key priority for the government and the health service. Here, we review our earlier projections for NHS waiting lists and, in light of their relative success, consider what those projections imply for the evolution of waiting lists over the coming year.

How have our waiting list projections fared?

In February 2022, we produced a set of projections for NHS waiting lists up to 2025. We presented four illustrative scenarios, each based on a different set of assumptions, using out-turn waiting list data up to December 2021. Our central scenario assumed that the NHS would achieve its target of increasing elective activity by 30% by 2024–25 (relative to pre-pandemic levels), and that half of the patients who would otherwise have been expected to join the waiting list during the pandemic (so-called ‘missing’ patients) would subsequently return to seek treatment. In an alternative ‘low’ scenario, we made the same assumption around NHS activity levels, but assumed that 30% of the ‘missing’ patients would return. (For more information about how we produced our scenarios, and to see the other scenarios we produced, read our analysis from February.)

Figure 1 shows how our central and ‘low’ scenarios have since fared. The green line shows the out-turn data for the overall size of the waiting list up to December 2021. This is the data that were available when we produced our central and ‘low’ scenarios, which are shown by the yellow and red lines, respectively. The blue line then shows how waiting lists have grown between January and September 2022. The blue line is somewhere between our central and ‘low’ scenarios. In the latest month for which there are available data, September 2022, our central and ‘low’ scenarios predicted 7.3 and 6.9 million incomplete waiting list pathways, respectively. In reality, there were 7.1 million.

However, although our projections for waiting lists have in hindsight proved quite accurate, this is due to two offsetting errors.

What has happened to NHS treatment volumes?

Our central and ‘low’ scenarios assumed that the NHS would increase its treatment capacity rapidly, and successfully achieve its target of 30% higher elective (pre-planned) volumes in 2024–25 compared to 2019. This meant that by September 2022 we assumed treatment capacity would be 6% above 2019 levels. But this has not happened. Instead the NHS has struggled to increase its volumes above 2019 levels at all. 

Figure 2 shows how NHS treatment volumes from the waiting list have changed compared to 2019. Between January and September 2019, the NHS completed 12.4 million pathways from the waiting list. Over the same period in 2022, it completed 11.8 million pathways, 5% fewer than in 2019. In other words, the NHS has treated fewer people from the waiting list than we expected, and so the number of people leaving the waiting list each month has been lower than we assumed. All else being equal, that would lead to the size of the waiting list growing more quickly than we projected.

What has happened to the number of new joiners?

The other key assumption for our central scenario was that 50% of those who missed out on care during the pandemic (so-called missing patients) would subsequently join the waiting list (30% in the ‘low’ scenario). We also assumed that the number of ‘regular’ waiting list joiners would grow in line with the growth assumed in the NHS Long Term Plan, due to long-term population changes. 

In the event, these assumptions over-estimated the number of people joining the waiting list. By September 2022, we assumed in our central scenario that the number of joiners would be 15% above its 2019 level. In reality, the number of new joiners was 0.4% below its 2019 level. This is below even what the pre-Covid NHS Long Term Plan growth rate would imply, and therefore suggests that there were relatively few missing patients returning and joining the waiting list. All else being equal, fewer people joining the waiting list would mean the overall backlog growing more slowly than we projected.  

What does this mean for the future of waiting lists?

These two trends (fewer people leaving the waiting list after being treated, but also fewer people joining) have more or less cancelled out. Our central and ‘low’ scenarios for the size of the overall waiting list have each turned out quite close to what actually happened as a result: the actual figure for September 2022 lies almost equidistant between the two. 

But there is no reason to think that that these errors will necessarily continue to offset each other. Our central scenario predicted that waiting lists would peak at 8.7 million and then start to fall only by the end of 2023; our ‘low’ scenario predicted that lists would peak at 7.4 million in the middle of 2023. But whether or not the size of the waiting list does in fact start to fall in 2023 depends on what happens next to NHS treatment volumes and to the number of new joiners.

If the NHS continues to struggle to increase treatment volumes, it is unlikely that waiting lists will start to fall any time soon. At the moment, the NHS has only been saved from even higher waiting lists because fewer ‘missing’ patients are joining the waiting list, either because they have continued not to seek care or because they have not been referred for hospital treatment even after seeking it. This risks its own set of problems if people do not receive the care they need. It is possible that the number of patients joining the waiting list will surge in the coming months, but we think it is unlikely, given that no such surge has occurred over the past year. 

Instead, what will happen to waiting lists likely rests on how many patients the NHS can treat. If the NHS is able to increase its treatment volumes substantially above 2019 levels, then waiting lists may well start falling in 2023. We will produce an updated set of projections in the Spring. In the meantime, we think that this remains a reasonable central projection. But treatment volumes have remained stubbornly below pre-pandemic levels for all of 2022 so far, and the target of increasing volumes by 30% by 2024–25 looks increasingly ambitious and potentially beyond reach. If the NHS continues to struggle to increase its overall level of activity, waiting lists could feasibly continue on a rising path well beyond next year. 

The key issue, then, is whether the NHS can successfully increase treatment volumes, and what factors might be preventing it from doing so. In the second part of this three-part series analysing the current challenges facing the NHS, we will focus on the financial and staffing resources available to the NHS and how this relates to the amount of care the NHS can provide.

[1] Some people are on NHS waiting lists several times for different treatment pathways, and so the true number of people waiting for NHS treatment is estimated to be closer to 5.5 million. But to a first approximation, the relevant number for the NHS is the amount of treatment it needs to provide, not the number of unique individuals it needs to provide that treatment to, and so we focus on the headline number of waiting list pathways.