Ann: ResApp Provides Updated Australian Paediatric Study Results, page-184

A few further thoughts before the main meal is served in July.

The Australian results compared clinical diagnosis to the cough test.

The American study will compare the cough test to clinical diagnosis and radiological diagnosis

What do people think will happen?

My first thought is the population studied may differ in fundamental ways ways from the ultimate target...telehealth and developing world.

Firstly, those presenting to a major first world hospital with quaternary level care are more likely to come from a different socioeconomic stratum.

They are also likely to be much sicker than those who present to primary care.

We know that sensitivity and specificity vary with the prevalance of the target condition in the population.

Since the prevalance of pneumonia will be higher in the ED presenters, we can expect better diagnosis in this setting, versus community general practice, where the prevalance will be much lower.

At the sicker end, the diagnosis should be more obvious than a pneumonia early in evolution, which is a presentation more likely in the teleheath or GP setting, or a non-pneumonia presentation.

Why is this important? Because it can affect the PPA and NPA. What we are looking for is a test that can detect pneumonia accurately EARLY when the picture is less certain because that makes a difference in the outcome.

That said, you might think the bias in SMARTCOUGH-C will be toward agreement with hospital ED diagnosis rather than away, so from an investor viewpoint that may favour a better result.

Next thought, clinical and radiological diagnosis are fundamentally different.

The cough test presumably measures the pitch, type of wheeze and crackle type. These are what are listened to with a stethoscope. But a stethoscope also listens for reduced breath sounds and bronchial breathing, which may carry a greater likelihood ratio of diagnosis of pneumonia. Hands are also used to detect reduced vibration over the affected lung area as well as dullness to percussion.

So, in effect the cough test "more accurate than a stethoscope" is replacing these signs, but is best compared to the likelihood ratio for pitch, crackle and wheeze as these are the direct comparison clinically. It is a big ask to replace the other signs as well, given that the signs elicited are not just from a stethscope.

As for radiological diagnosis, how accurate is it as a stand alone test? chest xray finding may not appear at the time of presentation. They may turn up days later. The findings themselves may be uncertain. It will be interesting to see how this is handled in the study. Remember, the PPA and NPA are measures of agreement not necessarily truth.

Last thought, will this truly influence antibiotic prescription in the developing world? Often in SE Asia antibiotics are available over the counter at the chemist. Antibiotics for community acquired pneumonia are cheap. If you have only a few bucks to spend, will it be on the cough test or the antibiotic?

I'm not even that sure it would influence decision-making in mature economies in a major way. If in doubt, I would think the path of least regret overall is to treat, as the harm from missed diagnosis is likely to outweigh the risk of allergy and the broader issue of promoting selection of resistant organisms.

The population where it presumably will be marketed to most is the low prevalance population and the accuracy of the test in those conditions will be important. Maybe this will be a followup study.

You can call me a wet blanket, I don't mind. Just throwing a few ideas in to balance the argument. It may rocket into prominence for all I know. As an investor, like all here my bias is to self-interest. No misty eyes about granny from me