Feature

Do-it-yourself health diagnostics

The DIY philosophy, which is now spreading to over-the-counter health diagnosis, should not be dismissed out of hand, claims Ken Green

Since the middle of last year, certain shops have been inviting members of the public to walk in and have their blood cholesterol measured. Is this a good thing? Most doctors in Britain think not. They are also firmly against general population cholesterol screening as a strategy for preventing coronary heart disease. The Department of Health, whose medical advisory committee is discussing the matter, is by all accounts likely to concur with this opposition. DoH and medical profession opposition extends to other kinds of over-the-counter testing, such as for blood pressure, and (except for pregnancy testing) do-it-yourself home testing of urine and blood in general.

But are they right to oppose over-the-counter testing? The pressure for an extension of this sort of testing, outside the NHS and certainly outside the direct control of doctors, will not go away. Shouldn’t a progressive healthcare policy therefore try to harness it for better health instead of opposing it outright?

Worldwide there is considerable dispute over whether it is worth checking an entire population’s blood cholesterol as part of a health service-backed screening programme. In the US, the assertion that ‘all adult Americans should know their cholesterol number’ has been accepted as part of a national campaign. According to John Catford of the Welsh Health Promotion Authority, who reviewed the US experience at a recent King’s Fund forum on blood cholesterol measurement: ‘Opportunistic screening by physicians has increased ninefold since 1982. Between 1987 and 1988 the number of medical visits for hypercholseterolaemia (high blood cholesterol) doubled. Drug prescribing for hypocholesterolaemic drugs has also increased markedly.’ Apparently, even supermarkets offer fingerprick testing.

In Britain the Royal Pharmaceutical Society openly supports cholesterol testing as a service to be offered in British chemist shops as ‘a natural part of the extension of the pharmacist’s role in illness prevention and health promotion’. A three month pilot scheme last year in half a dozen chemists showed considerable demand for the service, and more shops have been offering it this year. The health food chain, Holland and Barrett has also introduced a testing service.

To do the tests, a pharmacist first takes a fingerprick blood sample. This sample is applied to a reactive strip which is inserted into a desktop analyser (chemist shops are using the Reflotron machine). After three minutes the machine gives a read out of the cholesterol concentration in the blood. The speed and simplicity of the procedure do not reflect its technological complexity. The strip and the analyser are the product of years of development.

There are certainly valid arguments against mass cholesterol screening as a central element in a coronary prevention programme. Not least is the possibility that screen will tend to favour drug therapies over preventive strategies such as improved nutrition and reduced smoking. (see healthmatters 2)

A big worry about chemist shop testing is that the results are not reliable. A recent survey of GP use of the Reflotron found a variation in results so wide as to be therapeutically unreliable. Combine wrongly-set or badly-maintained analysers with sloppy users (taking proper blood samples is not a simple matter) and you get useless results, which may also be dangerous for the patient if they induce complacency or create unnecessary anxiety.

But the issue will not go away. Over the next 10 years, technological progress will bring more simple, cheap tests for more conditions on to the British market. Recently, there has been an upsurge in new types of tests based on advances in chemistry and biotechnology as well as in electronics. Compare the home pregnancy test kits of the early 1980s (all that mixing and waiting for the barely visible blue ring to form) with the rapid, simple and user-friendly kits of today. And there are many other tests with the same characteristics — for ovulation testing, for infectious diseases like Strep sore throat, for faecal blood. There is even a five minute test for HIV antibodies in a drop of blood. Many others are being developed to detect the presence of a wide variety of infectious bacteria and to identify markets for various cancers.

So far, only pregnancy and ovulation kits are widely available to the public in Britain. The HIV test is in fact banned outside licensed laboratories. But tests are likely to become more generally available in other countries. Already, the healthcare finance system in the US encourages American doctors to do more testing than their British counterparts, and the situation in West Germany is similar.

We need a more constructive and systematic response to new tests. Otherwise we will keep going over the same arguments when other medical conditions become ‘screenable’ through DIY testing. I take the view that self testing or chemist shop testing based on cheap, easy to use technologies (that is, not carried out under medical professional control) should not be opposed in principle. They can be seen as a valuable aspect of self-help in healthcare. Rather than just reacting to new tests and campaigns developed by US/German diagnostics firms — which are often linked to dubious and unsatisfactory drug therapy strategies — we need to take a more active approach. We need to define some criteria for the kinds of self- help tests we might want.

Pregnancy test kits provide an admirable model for over-the-counter DIY tests: they are sensitive and specific with clear instructions and crucially, clear ‘therapeutic’ consequences. In addition, a manufacturer-financed helpline is provided for queries. New home tests should be expected to conform to this model. Testing in shops, whether chemists, supermarkets or health food premises, should be subject to certain conditions.

All potential testers should be trained in the taking of samples, the operation of the equipment and elementary maintenance and machine calibration. Test equipment manufacturers could pay for training. There should be rules on the regular servicing of equipment. Written results should be provided to the ‘patient’. Instructions on what to do with the results should be provided in literature approved by the NHS, since there may be consequences for the health service in follow-up test and treatment. Level of precision should be drawn up as targets for manufacturers in developing their technologies.

DIY and walk-in shop testing will never be a major component of healthcare. Such tests do, however, have a role to play in illness prevention and health monitoring. But the questions remain: What should that role be? And what rules should be set?