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What do all those numbers really mean doc?

15 Jun, 14 | by Toby Hillman


What is ‘normal’

Go into hospital nowadays, and you will do well to escape without having a blood test of some sort.  Very often these are routine tests, which give doctors an overview of the state of play. There might be a few wayward figures here or there – but the doctors will ignore them, or explain them away as part of the normal variation of homeostasis.

In the PMJ this month the spotlight turns to one biomarker that is commonly requested when patients are admitted to hospital.  Indeed, the troponin is one test which I see regularly used completely out of context, and providing information which is often difficult to assimilate into the clinical picture.  The paper – an analysis of >11000 admissions to a large medical facility in Dublin, Ireland has examined troponin results for all admissions under the medical (but not cardiology) service from January 2011 to October 2012.

Now, the troponin is a test that has undergone a change over the time that it has been available to clinicians in everyday practice.  I can remember taking serial CKs in patients with suspected myocardial ischaemia, and my joy at the troponin becoming available for use in my potential CCU patients.  I can also remember the many patients who have been admitted to hospital for 12 hours just to see what their troponin will be – a clear case of a biomarker dictating practise, rather than been a tool for me to use.  And I have many memories of strained conversations with colleagues about the meaning of a mildly raised troponin which had been requested as part of a bundle of tests at the point of admission – without any real thought being given to how one might interpret the results.

These strained conversations have altered in tpne over the years as the blind faith in the value of troponin to indicate ischaemic heart disease which accompanied the hype of the test when it was first released, has been eroded by realisation that troponin is no way near as specific as we were once led to believe – and interpretation now requires quite a lot of Bayesian reasoning to clear the waters.

The article looking at troponin tests on the acute medical take makes a fascinating read, and helps provide some data to the consideration of the not uncommon problem – “well what do I do with this result now?”

The answer in the case of an unexpected elevated troponin is to consider the overall clinical context, and attempt to understand where the physiological stress has proceeded from, as this study shows a significant association between elevated troponin and mortality:

Exponential relationship between high-sensitivity troponin assay (hsTnT) results and in-hospital mortality.

So – a helpful paper looking at a common clinical scenario, and providing a fairly robust argument for how to approach the problem.

But one of the most fascinating parts of this analysis is the determination of what is ‘normal’ and why do we love to have such binary answers to complex questions?

The manufacturers of the assay employed recommend a cut-off of 14ng/L for the normal range. But, given that the test isn’t as specific for myocardial injury as they would like – a figure of ≥53ng/L should be used to indicate myocardial ischaemia. For the purposes of the published study a figure of <25ng/L is used as the cut-of for normal, and ≥25 as ‘positive.’

The persistence of a desire to classify a test result that the outcome of this large observational study indicate is a sliding scale, indicating physiological stress, rather than any specific disease process (in this study that effectively excluded cardiac disorders as the presenting complaint) into normal and abnormal categories belies a huge cognitive bias that we all carry around with us. Essentially we like to make judgements based on prior experience, heuristics, and easily interpreted chunks of information – what David Khaneman would call a ‘System 1″ or ‘fast” process. We do this regularly with a high degree of accuracy when on the acute take.

What this paper could be seen to do is boil down a clinical problem into another readily available answer, that can be applied in everyday practice – to me, it is a reminder of the blind faith I used to have in a test that I and it’s manufacturers understood poorly, and drove clinical protocols and pathways, rather than me applying some critical thinking to my actions, and their results – and using the test to its best effect.  I wonder how many more biomarkers we will see undergoing this sort of evolution.

Can do, or should do?

17 Mar, 14 | by Toby Hillman


Modern medicine is advancing at an eye-watering pace, and treatments are being utilised for ever-widening patient groups, who might not have been offered similar therapies even a few short years ago.  In this context, it is increasingly important to know that these remarkably effective, expensive, and life-changing treatments are aligned with the wishes of our patients.

Renal medicine is just such an area where a once relatively rare treatment, offered to relatively few patients (HD) is now being offered to an expanding pool of patients.  In a paper in last month’s PMJ, Davison and Sheerin describe some of the challenges around the provision of HD to patients with CKD.

There can be no doubt that HD makes a huge difference to patients with CKD who require it – both positive and negative.  However, it was surprising to read that some studies have found up to 60% of patients on HD regretted the decision.  Sadly it was less surprising to see that a number of these patients felt that either their families or their physicians played a role in ‘pressuring’ patients to embark on this treatment.

Doctors train for many years to be able to manage diseases, put off the inevitable, and maintain the functioning of vital organs through acute and chronic illness.  As such it is entirely understandable that they would wish to offer treatments they have at their disposal to their patients, especially where these treatments can confer a survival advantage. However, the doctors involved in these decisions may not be best placed to ensure that these treatments are initiated for the correct reasons… and it is a feature of many consultations I have had with patients over the years that they often take actions to please their relatives – even if their own preference might be something else entirely.

As we enter the sunset of the baby boom generation, and we develop ever more effective treatments to treat once terminal illnesses, the medical profession must start to take the idea of patient preference more seriously.  This is especially so where resources are scarce, and making the wrong diagnosis of patient preference can lead to (potentially) years of treatments which the patient may well regret starting in the first place, or to missed opportunities to intervene when assumptions have been made in the opposite direction.

There are two key steps that we must make to move towards true patient choice.

One is by enhancing our skills at sharing decision making with our patients and for specialist services to start developing relationships with patients that allow a better understanding of their hopes, concerns and expectations for the future. As Iona Heath pointed out in her fantastic Harveian Oration in 2011 – GPs tend to deal with one set of patients, but their illnesses change over time, but specialists tend to deal with fewer diseases, but it is the patients that come and go.  As such, specialists will be on the back foot when it comes to developing a deep understanding of the true wishes of their patients, but with time, care and with the right tools  it is possible to get nearer to the ideal scenario for our patients.

The other is to realise that just because we can do something, doesn’t mean that we should.  This last issue may take a little longer to resolve.  Diane Plamping highlighted this ‘can do, should do, and that doing means treatment’ thinking as a central tenet of working in the NHS  in an article for the 50th anniversary of the organisation.  She offered no quick fix, but does encourage us to talk about ‘can do, should do’ with our colleagues.  I would suggest that we should discuss this with our patients.  For those we have known for a long time, we will be halfway towards knowing their true preferences, for those who we have met more recently, we need to afford a little more time to ensure that we make perhaps the most important diagnosis when it comes to long-term conditions – the patient’s preference.

It’s not about the form… it’s the human touch

20 Oct, 13 | by Toby Hillman

A ‘typical’ request form?

There are several problems which rear their ugly head every few months / years in healthcare and yet seem impossible to crack.

In the main they pass by, unnoticed by the great and the good, and not usually causing discernible problems for patients.  But, time taken to gather phlebotomy equipment, delays in prescribing ‘TTAs’ and ordering too many tests are all a waste of resource.

Waste is the enemy of efficiency in any system, and the 7 wastes:

  • transportation
  • inventory
  • motion
  • waiting
  • over-processing
  • over-production
  • defects in work performed

are the target of many improvement projects (especially those relying on lean thinking)

One such improvement project has shown a successful, and sustained reduction in the waste of excessive laboratory tests.


The paper reports the process undertaken to introduce a change in the practices of an emergency department, through a forcing function of only allowing junior staff to order tests once a senior had approved the request.  The largest excesses in requests were targeted and significant changes over time were achieved.
The report puts some of the change into context, but I wonder if a follow up, qualitative study might be required to really evaluate what changed.

I may be wrong, but this intervention doesn’t seem like one which was imposed rigidly from above, but instead was developed in collaboration with the key clinical decision makers in the department, and with an eye on what would actually work on the ground – in *their* department.

And this is the messy bit.

For senior clinicians, and managers who see the headline: ‘Change in form reduces tests, saves $$$‘ there could be a shock coming.

Firstly, the change took time to bed down – see the histograms for the weeks after the intervention – so no quick fix.

Secondly – don’t kid yourself that it was the change in the form which made the difference – it was a shared vision for change from senior, middle and (probably) junior grade doctors.  After signing up to a shared goal, there was a change in working practices, backed up by a staffing and service delivery model (note the absence of a 4 hour target, and retention of responsibility by the ED for short stay patients) which encouraged a dialogue between seniors and trainees. Moreover – and crucially, in my view – the change opened up the possibility of real-time, on the job, training.

Each interaction for an additional request seems like it will have been a discussion point – and trainees benefitted from a culture of learning within the department.

So, could this be reproduced in the UK? In some departments, I’m sure, in others – no way.

In trying to replicate such successes we should not concentrate on the mechanics of the intervention, but the human factors and cultural context. Work on that, alongside such innovations and you stand a much better chance if success.

For more information on human factors (if you’ve not heard the phrase – look it up – it could change how you view your world and where you work) then see the Clinical Human Factors Group  and an inspirational video on human factors in patient safety from the incredible Martin Bromiley:

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