Bottom line for the short of attention span / don’t like detail folk
The proposition to screen for AF doesn’t pass the NSC criteria
It nearly does, but didn’t at last review. 2014?
Fails on a number ofcriteria:-
- Non optimised population. Why find new people to treat when you suboptimally manage the risk in those you already know about
- No RCT proving screening improves outcomes, this in is a closer run thing – see the nuances below.
- Cost effectiveness of the screening programme as a whole (not just the treatment part)
- Certainly not cost effective if using NOACs or DOACs or whatever they are called this month
- Def not affordable if using DOACs
Nb my COI is directly relevant here, see main page.
So onto the detail……
I should be clear – Lots of testing is happening anyway in ad hoc fashion, random pick up based on presenting issues and symptoms. This is I’d call a “test” or “making a diagnosis”.
“Screening” is a population focused phenomena that implies organised population screening – pop, test, programme, QA standards etc.
So, onto the substantive answer to question I was put.
I was asked this q by a cardiology prof. It required me to have a think. My answer is below.
1. Some context before I get onto AF per se.
The below is about the uk and NSC, I’m not familiar with processes in other countries, I have a passing knowledge of USPTF.
I’m not a member of NSC. Just an interested, and relatively well informed, observer.
Im generally anti screening – contrary to popular opinion, most public health types are!
A number of reasons for this –
a) Screening saves lives language (rarely does – mostly reduces cause specific mortality, rather than all cause mortality – often by a marginal fraction) – this is a nuanced message and difficult to convey in a press soundbite (unlike – “screening saves lives”).
b) Its more often the case than not that screening isn’t especially cost effective.
c) Theres a vast amount of “screening” that goes under the guise of “case finding in high risk groups”. This is based often on a notion that “testing (word used advisedly) cant do harm.
This is where I get particularly grumpy
It can, if nothing else it can waste somebody elses health care (through opportunity cost).
Plenty of evidence of direct harm also.
There’s also the harm that can come from what’s termed the diagnostic cascade arising from the initial test – well documented, and the harm from incidentalomas, again well documented but especially see here – https://m.youtube.com/watch?v=vrjx8ikME7Q
and more humorous take here – https://m.youtube.com/watch?v=gfesuNG0-kQ
Put simply, I fail to see a distinction between “case finding” and “screening”. In fact case finding (my def is – looking for disease in asymptomatic individuals, out with the context of an organised programme with clearly defined QA criteria) I often characterise as not much more than fishing.
I accept I’m quite hardline on this.
I once got asked the question by an eminent glitterati in the world of screening to try to define the difference between the two concepts. I failed to do so. Blog here -the genetics crew subsequently did find a few issues that were legit, can’t recall what off hand but was fairly niche territory.
2. On AF in particular
I have a slightly different view. General principles apply.
is important, and the consequence preventable – obviously.
SAFE (and other studies) have established some evidence on efficient ways to screen – both population and test, though the test (SAFE = pulse + confirmatory ECG) may have been superseded by hand held devices such as Alivecor (other brands available etc). I don’t know if the definitive studies comparing such devices against gold standard are yet done, I’m sure they have.
We have an effective treatment – obviously. It’s underused.
I’m aware NSC considered this a few years ago and recommended against considering on a number of grounds (from memory, I’ve not re read the docs):
a) Non optimised treatment in current cohort. Why find new cases when we currently poorly manage risk in the cases we know about.
b) Uncertainty in whether the stroke risk in asymptomatic patients (ie the group you’d find with screening) is the same when considered against a symptomatic cohort. Obviously would affect the risk / benefit balance, and especially given the ethical conundrums inherent in screening (inviting someone who thinks they are healthy to have a test, tell them they have a disease and offer them a treatment that does carry risk etc). I’d seen some data off the back of one of prof Fitzmaurice’s studies that suggested the risk WAS equivalent, ie in favour of screening. But it was a small cohort on the back of an observational study. Ideally an RCT should be done but it never will I’d guess. I heard that the NSC had asked for some further modelling to be done on that basis. Not sure where it got to.
c) Uncertainties re cost effectiveness of screening programme with subsequent treatment. Made all the more difficult in a (much more expensive but equally effective) NOAC (or whatever we call them this month) era.
So my take on a proposition for AF screening is “nearly satisfies NSC criteria but not quite”. The world may doubtless have moved on since I (or more importantly the NSC) last thought hard about it.
So to answer the question directly-
The above points would need to be addressed in order for NSC to change its position.
To be fair to it (NSC) it can only cope with so many proposed programmes (remember everyone wants to screen for everything cos it either makes someone money or saves lives etc).
Thus scheduling a review of the position statements and policy recommendations is tricky and difficult.
And NSC can only go on what evidence is available at the time of the review, how this is presented and with what spin. It makes tough calls based on this.
In my view we shouldn’t screen till a potential programme (ie more than just the test) clearly satisfied the Wilson Jungner criteria. This stands for AF also.
In the UK, as I figure you know, National Screening Committee is an expert scientific advisory group that advise the 4 UK governments on screening policy. The NSC use a modified version of WJ criteria. Acts in similar way to say the USPTF, arguably a little more hard line.
There are plenty of examples on where screening policy decisions haven’t been through the NSC. Health checks and chlamydia screening are pertinent examples.
More recently there have been some discrepancies between NICE AND NSC in some areas for example diabetes and PH38 which effectively recommends screening. I’ve fallen out with a few on this one:
Even when all what is addressed, see the conclusion to this editorial
Before we can introduce a national screening programme, we need to know from randomised trials whether or not AF screening is effective at reducing cardiovascular morbidity and mortality. There are ongoing trials exploring this question in Sweden and the Netherlands, and more are planned. If screening is effective, there are several operational issues that need to be addressed before a national screening programme can be introduced: What is the optimal target population? What is the optimal screening technology? How best to confirm that screen-positive people do have AF? How to ensure fully informed patient choice, both with regard to acceptance of screening, and subsequent treatment if found to have AF?
There is strong potential for public health gain in screening for AF, but, as yet, the evidence base is unlikely sufficient for a national programme.
Here maybe an example of NICE making de facto screening recommendations without having fully considered WJ criteria and a different take on the evidential question than NSC would have.
So that’s my view…..I accept its a bit hardline. happy to chat more?