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gary
11-03-2007, 06:57 PM
Thank you for voting on this thread and poll. This is a matter completely unconnected with this website and I do appreciate your comments and observations.

For some years now I have been developing a new type of medical device with the aim of making it easier for GPs to recognise and diagnose malignant melanoma. I have been awarded 2 DTI Smart awards over the years in this project, which is now being undertaken by a company called Zeal Diagnostic ( I am the MD, it is a subsidiary of the Zeal Healthcare Group).

The device is called a "Thermal Ruler" and it simply measures the surface skin temperature across a skin lesion, plotting it versus distance on a small LCD display.
http://gpmanagement.co.uk/images/thermalruler-zeal.jpg
A melanoma shows itself by producing a rise in temperature. About 84% of melanomas are hot, 44% of them by more than 1 degree Celsius. For a lesion that is recorded as being more than 1 degree C hotter than its surrounding skin the PPV ( positive predictive value) is 96%.

I won't go into the thermal properties of melanomas here, but the science as is now known is sketchy, as most of the work was done years ago with thermal imagers, which are very expensive. The Thermal Ruler is a low cost solution that enables thermal profiles to be read, but with simple technology.

The same device can also be used in other areas of GP practice. For instance there is a potential use in quantifying Raynaud's disease, peripheral vascular disease, sciatic nerve disease, the diabetic foot, burn assessments and complex pain syndromes.

The situation with regards to development is that the device could be finished from an engineering point-of-view within a few months. It is a first generation device and it works well, but only on easily accessible areas of skin ( large limbs, back, abdomen). Other body areas require some user expertise.

What I would like to know is what demand there is for such a device within General Practice. This is a difficult thing to estimate for what is " the first of its kind". However I need to have some understanding of this demand, as it enables my superiors at Zeal to commit the sums of money required to finish off the development. ( we are within 3 months of finishing the engineering and all the regulatory hurdles, after which we will able to supply units)

Estimated purchase cost is 750, runs of PP3 battery, optional printer.

Your involvement with this poll is greatly appreciated.

raineshoe
12-03-2007, 01:09 PM
Sounds interesting, but I honestly can't see the GP I work for buying one as he is soooooo careful with his pennies.

chhaya shah
12-03-2007, 01:17 PM
we do not use thermal ruler in our practice as we have always referred patient to hospital,
may be useful for Diabetic clinic but not very keen to purchase

charmagne
12-03-2007, 01:25 PM
I can see the value in this piece of equipment, however it is a cost I cannot imagine GP's picking up in primary care as even though it diagnosis the problem the pateints would still need referral to an acute trust for treatment.

Patricia Crates
12-03-2007, 01:37 PM
We are setting up a locality dermatology clinic under PBC so there may be scope for approaching the clinician:

rdeacon
12-03-2007, 03:01 PM
To be honest voted but had no idea what a thermal ruler was!!:confused:

ddugmore
12-03-2007, 03:01 PM
There is a zero percent chance of my senior partner sactioning the purchase of such an item.

pruritus
12-03-2007, 03:11 PM
Always looking for a useful bit of kit in this price range to spend the Prescribing Incentive Scheme money on. Not allowed as cash must be on something for the patient benefit. Other areas of UK still get this?

owain_thomas
12-03-2007, 03:29 PM
Hi,

I think this is very interresting. I do minor surgery for our practice but also as a GPSI for the PCT so I see a lot of moles and skin lesions.

The one thing that would concern me though is that the vast majority of lesions we see are NOT melanomas, I would be more interested in a device that easily ruled the diagnosis OUT rather than IN. what is the negative predictive value for the device?

owain

gary
12-03-2007, 04:08 PM
Hi,

I think this is very interresting. I do minor surgery for our practice but also as a GPSI for the PCT so I see a lot of moles and skin lesions.

The one thing that would concern me though is that the vast majority of lesions we see are NOT melanomas, I would be more interested in a device that easily ruled the diagnosis OUT rather than IN. what is the negative predictive value for the device?

owain

The PPV was taken from a study by Michel et al 1985 on a series of about 260 skin lesions, the majority of which were melanomas ( details not to hand immediately as I write this). The study compared thermal imaging with expert opinion. surprisingly the experts opinion had a disastrous negative predictive value, as all the lesions that they identidfied as benign turned out to be maligant. essentially the study only looked at melanomas, so really only the PPV can be accurately assessed. as I said - the science is sketchy, because of findings like this.
I have attached an overview of the Michel study

owain_thomas
12-03-2007, 04:58 PM
The PPV was taken from a study by Michel et al 1985 on a series of about 260 skin lesions, the majority of which were melanomas ( details not to hand immediately as I write this). The study compared thermal imaging with expert opinion. surprisingly the experts opinion had a disastrous negative predictive value, as all the lesions that they identidfied as benign turned out to be maligant. essentially the study only looked at melanomas, so really only the PPV can be accurately assessed. as I said - the science is sketchy, because of findings like this.

Hi Gary,

thanks for the reply. I think that is the reason I would be sceptical about purchasing such a device.

On one level I'm quite intrigued by it, but for it to be useful it would have to help me change my management of suspicious lesions. I'm not sure it could.

If it were able to provide reassurance in lesions which were, on clinical grounds, not high-risk then I would find it VERY useful and probably worth the price. As it is I'm not sure how it would alter my referral patterns sufficiently to be worth the expense.

Hope that makes sense,

best regards,
owain

geoffdennis
13-03-2007, 04:24 PM
Commebt from one of my GPs:
''An interesting concept but utterly unproven as of any use!
At present a definate 'no' to interest in purchase.
However it looks as if it should be investigated. It would be relatively easy to run a trial in a dermatology referral unit to assess the accuracy of the device against subsequent excision histology. It could also be tested against a specialist's 'intention to treat' but as he mentions this might be less than definative.
These sort of devices should be investigated for their potential but should not be marketed without a convincing evidence base to support and inform their use.''

gary
13-03-2007, 11:35 PM
Commebt from one of my GPs:
''An interesting concept but utterly unproven as of any use!
At present a definate 'no' to interest in purchase.
However it looks as if it should be investigated. It would be relatively easy to run a trial in a dermatology referral unit to assess the accuracy of the device against subsequent excision histology. It could also be tested against a specialist's 'intention to treat' but as he mentions this might be less than definative.
These sort of devices should be investigated for their potential but should not be marketed without a convincing evidence base to support and inform their use.''

this is precicely the point as to why the device is called a "Thermal Ruler" rather than a "melanoma detector". It is a tool that just adds knowledge of a temperature profile, spatially. A spatially aware thermometer. after all - the clinical themometer is not called a " pneumonia detector". therefore, as it is intended to be a " generic" basic parameter assessment device rather than an interpretive device, it will be marketed as such ( if and when we get that far), and won't claim ability to detect melanoma, just the ability to measure differential skin temperature. it will be these differential skin temperatures that will have to be interpreted clinically, and which will have predictive values/accuracy indices attached to them, and which will be associated with particular clinical pathways.
I take your point about being clinically proven though. Lot of work needs to be done before we know how best to use the device. However- that doesnt preclude anyone with an interest trying it out, and as the device is aimed at primary care...

simon
15-03-2007, 05:03 PM
Looks good to me - although I would imagine that its use would mainly be confined to community dermatology type clinics set up under PBC - I'm not sure that we would see enough of these in General Practice to justify the expenditure - unless we had a really good summer, of course!:cool: