Thursday, 25 January 2018

The week in bullshit, continued…

Last week I fired off a rant about how politicians misuse statistics to win arguments with little regard for the relevance or context of the numbers thereby doing extreme violence to honesty and truth telling. This week I find yet more examples from the NHS.

Here is why the specific instances constitute bullshit.

The Prime Minister said the following in Prime Minister's Questions on January 24 in response to a Jeremy Corbyn complaint about poor performance in the English NHS over winter:

If he wants to talk about figures and about targets being missed, yes, the latest figures show that, in England, 497 people were waiting more than 12 hours, but the latest figures also show that, under the Labour Government in Wales, 3,741 people were waiting more than 12 hours.

Corbyn didn't spot the problem (I presume neither he nor his advisors are any more knowledgeable about these statistics than the PM or her health minister).

But it is quite a simple issue: the Welsh NHS counts something different when it measures 12hr A&E waits than the English NHS. In Wales, the clock starts when the patient arrives; in England the clock starts when a decision is made to admit the patient to a bed. This decision is highly gameable and is highly gamed. Even without any explicit fiddling of the numbers (there are rumours that some management teams stop their teams recording a time in a timely way to reduce their reported numbers) the decision is often postponed until the hospital knows there is a bed available. This may happen after the patient has already waited 12 hours in A&E.

The English "trolley wait" metric is a terrible, useless and misleading metric. It actively distracts from a good understanding of the problem of long A&E waits. Yet here we have a politician using it to win an argument with the opposition instead of trying to understand what is going on in A&E.

Here is some help to put it in context. The comparable number is accessible from data collected from hospitals (it is trivial to calculate true 12hr waits from A&E HES data, it just isn't routinely done and won't yet be available for this winter as national HES takes a few months to compile). In january 2017 there were 46,413 true 12hr waits in English A&Es (these figures were release by NHS Digital after an FOI request). That is the comparable number May should have quoted (if she had an up to date version of it which we have no reason at all to assume would be better in January 2018). If anyone in the system cared to have reliable and useful numbers to tell them how A&E was performing, they could easily collect these numbers on the same basis as Wales enabling them to have a much better and ungameable insight into what is really happening. Guess why they don't do that.

The disease, unfortunately, runs deep. Here are some extracts from Pauline Phillip's report on winter pressures to the NHS Improvement board on january 24: information for January suggests an improvement and the system is performing better than at the same point last year… 
[compare to this a few paragraphs later]
...A&E performance for December was 85.1%. This is 3.8ppt below the previous month (88.9%) and 1.0ppt lower than the same time last year...

...Performance is impacted by higher bed occupancy than last year and increases in attendances and emergency admissions...

[a few paragraphs later]
...Type 1 attendance growth compared to the same month last year is 1.0%.

[a 1% increase in attendance is actually below the long term trend in increases, though, to be fair, admissions were up by a much larger amount and they matter more. OTOH the excuse that "performance is impacted by...increases in attendances" is not the most accurate way to report the situation]

...the trend for much lower long trolley waits continues; 12 hour waits are 10% lower compared to the same time last year.

The problem here is that the text is frequently misleading when compared to the numbers quoted (always a danger when people are allowed to write paragraphs of bullshit instead of showing the clearest analysis of the key data points in context). And Philip, who should know better having run one of the hospitals with an outstanding A&E department) goes on to use the same trolley wait statistic that the PM quoted in her answer to make a claim that things are improving. It is such an unreliable statistic it tells us no such thing.

If you are going to manage A&E better you need to use numbers that are reliable indicators of what is really going on. Not terribly misleading numbers that are both a poor, misleading metric and utterly gameable. The trolley wait metric should have been burned years ago.

Maybe this point is simply not understood and the politicians and NHS leaders just don't get that this statistic is bullshit. Maybe this interpretation lowers their culpability for promulgating bullshit, but it is hardly comforting that the people in charge of improvement don't seem to possess the basic knowledge that any competent analyst of A&E statistics has known for years.

The reason why England doesn't routinely release reliable numbers about long waits in A&E is that they are very embarrassing. If they were widely used by NHS Improvement, as they should be, to understand what was really happening so their efforts could be focussed on generating real improvements, there would be a lot of bad headlines (which might be worth it if it helped but led to actual improvement). 

Sadly, in politics and organisations dominated by political management, improvement isn't the point: good headlines are all that matters. The impact of political bullshit is pervasive and corrosive.

PS. I'm not the only one who noticed. Faye Kirkland posted this on twitter just after I completed the original version of the blog. It is a letter to the Chair of the UK Statistics Authority pointing out just how misleading her comparison was. It will be interesting to see how he reacts.

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