Designing pathology services through studying demand

So I'm here at ECCMID2015 in lovely Copenhagen. It is clear that the predicted shift from culture to molecular is gaining pace. This will have a major impact on how we organise our laboratories and support clinical medicine. Many people see this as the death knell for local services. I will argue the contrary. For the first time, we have the tools in microbiology (beyond simple microscopy) to deliver results in a time frame that impacts on empirical decisions. In order to work, these tools need to be as near to the decision point as possible, as inevitably transport and other logistical issues will come to dominate the time taken to get a result. We will move from batch processing, to random access or point of care testing. These are things that local services can deliver, but that centralised reference laboratories cannot provide. The irony may be that it is reference labs that will remain the bastion of culture based methods (and perhaps non time critical molecular tests, such as viral load).

So that is all good. But in order to do this we need to change our thinking. We cannot replicate what we do with culture and just do it faster. We need to reconsider the questions we are asking and think about how the results we produce inform action. Just because you can do a test does not mean that you should. We heard today about how highly accurate molecular tests for tuberculosis actually perform poorly in low probability settings. So without considering exactly what test results mean, when applied to a specific setting, we run a real risk of doing more harm than good. And the mystique of molecular makes the risk of blind acceptance of results even greater. I will suggest that we need to go back to studying demand, and by that I mean asking what questions a patient would want to ask, and thinking about how we can answer them. So the question is not 'how can molecular do what I now do faster/better?' Rather it is, 'what clinical decisions can I now support using molecular?'.

And even more importantly, we need to be careful that we don't substitute good clinical assessment for the false security of a test result. Test results can only ever be interpreted in the context of the prior probability that flows from the extraction of clinically relevant information. We need to find ways that help us to resist the siren call of false reassurance, and back our clinical judgement when it is appropriate to do so.

The other concern I have is that small laboratories lack the skills with which to appraise these new technologies. It is easy to be bamboozled by reps promising sensitivities and specificities in excess of 99%, with business cases ready to pull from the shelf. What we need are experts who have a deep understanding of the emerging platforms, with attendant risks and benefits, and perhaps more importantly how they can be fitted together into a coherent package. We need advice on optimum staffing to run these services.

But these are certainly exciting times to be an infection specialist.