Assessing A&E: attendance patterns and waiting times performance

The performance of the NHS, and of Accident and Emergency units in particular, is a perennial hot topic in UK political debate. The House of Commons Library has published a report on A&E attendance and performance for the year 2013/14.

The report contains many interesting findings, several of which are counter-intuitive. In this post, Carl Baker draws attention to two of the more surprising findings from the upcoming paper.

Busy periods at A&E

When are A&E departments at their busiest? We might think that the winter months are busiest, since this is when we typically hear reports of strains on hospitals. In fact, the opposite is the case. January was the quietest month overall for A&E attendance at major departments, while the last week of December was the quietest week of all. (Despite this, January and February saw many areas registering some of their worst annual performance for waiting times.) The busiest period was in fact in the summer – in July 2013. A second busy period was experienced in March 2014. The following chart shows attendance patters across the year – with the deepest blue squares represents the quietest weeks, and the deepest orange squares representing the busiest week. Other shades represent values between these extremes.A&E Busy Periods2

However, the percentage of patients admitted via major departments was negatively correlated with the numbers of people attending major departments. In other words, busier weeks tended to be those in which a smaller proportion of attendees were later admitted to hospital, and vice versa. This could indicate either less variance across the year in the types of injuries serious enough to require admission, or instead could be explained by capacity constraints.

Patterns of annual attendance are remarkably similar across the country, although there are some notable regional variations. For instance, there is a spike in attendance at A&E in Devon and Cornwall in the month of August.

Waiting times at major departments

A&E departments are divided into three ‘types’ – types 1, 2 and 3 – with type 1 representing major departments, and types 2 and 3 representing specialist departments or minor units such as walk-in centres and minor injury units. Some NHS trusts oversee only major departments, others oversee only minor departments, and some oversee a mixture of the various types. One striking finding is that these different categories of NHS trusts perform differently in terms of waiting times.

Overall, 35% of NHS trusts met the ‘operational standard’ for waiting times in major departments – that is, 95% of patients waiting less than four hours from arrival to discharge, admission or transfer. However, while 59% of trusts who register all emergency attendance at major departments met the standard, only 18% of trusts with a mixture of major and minor emergency attendance succeeded in meeting it.

A&E waiting times

This is a surprising finding. We might expect that trusts with only major A&E departments would be under more strain – and so perform worse – because there are no minor injury units to stem the tide of patients attending A&E for any and every mishap. So why does the opposite appear to be the case? We can only speculate, but here is one possible explanation. If an NHS trust has only major A&E departments, and no walk-in centres or minor injury units, then those with minor scrapes and bruises may have no choice but to attend a major A&E unit. We know from the data that minor units typically have very good performance for waiting times – often at or near 100% of patients waiting for less than four hours – which suggests that minor injuries are easier to deal with within the target time. If trusts with only major departments are treating a greater than average proportion of minor injuries at major A&E units, then, we might expect their waiting time performance to be better than average.

By contrast, trusts with a mixture of major and minor units may find that patients with minor injuries are more likely to attend (e.g.) a walk-in centre – meaning that the remainder of attendances at the trust’s major A&E units are disproportionately for more serious injuries. If this is so, we would expect these cases to take longer on average to deal with, and so waiting times to be higher than average.

This is, of course, just a hypothesis. But it is one possible explanation of an interesting finding. This trend should be kept in mind when looking at the league tables of A&E performance. Our research paper to be released shortly reveals, for instance, that West Yorkshire – the best performing region for waiting times at major departments – is also the region in which the smallest percentage of A&E attendance is registered at minor departments.

Author: Carl Baker