Doctors are warning patients against using unregulated or ad hoc screening tests, saying they may cause more harm than good and give inconsistent results. This advice comes from a BMA (British Medical Association) report, Population screening and genetic testing1, out today, Tuesday 23 August 2005.

Whereas formal screening programmes2 evaluate entire populations and are based on national policy with a proven evidence-base, unregulated screening operates outside national guidelines and recommendations. The BMA is calling on the Government to address this issue.

Some examples of unregulated screening are:

� Whole body CT scanning (sophisticated x-ray) - this causes many false alarms leading to potentially dangerous invasive tests, and involves significant doses of radiation. There is no evidence that CT screening is useful for people without symptoms, but despite this some commercial companies are offering it and promoting it.

� Exercise electrocardiogram (ECG) - no authoritative body recommends this for people without symptoms of heart disease as it is far more likely to give a false result than to lead to useful findings.

� Mammograms (breast screening x-rays) in women under 50 - mammograms are useful for picking up breast cancer in women over 50, but evidence shows that in younger women small cancers are very hard to find and screening involves a high chance of misleading results. This can lead to further invasive tests and to surgery in many women whose cancers might never have progressed during their lifetime. This is why the NHS Breast Screening Programme offers screening from 50-70 but not under 50.

� Prostate Specific Antigen (PSA) testing to screen for prostate cancer - two thirds of men with high PSA do not have prostate cancer, some men with prostate cancer do not have high PSA, and no evidence exists to show whether treating localised prostate cancer does more good than harm.

The report, which comes from the BMA's Board of Science, states that unregulated screening can put patients at risk. This is because:

� tests are unlikely to be based on sound evidence;

� quality control of the testing may be non-existent;

� the tests are not part of a proper screening system leading to appropriate follow-up and effective intervention;

� balanced information for participants is very unlikely to be provided;

� information and support for patients after a positive result is unlikely to be in place.

The report is also critical of some aspects of private sector screening. Although some private screening is well delivered, and can have the advantage of more time available with a doctor, there are important concerns about harms from inappropriate tests, lack of continuity of care, quality assurance, and lack of support and advice. These concerns particularly apply to genetic testing.

Dr Vivienne Nathanson, the BMA's Head of Science and Ethics, commented:

"There is no doubt that some specific screening tests have the potential to save lives but this does not mean that there are no associated risks. We must make sure that screening is of a high quality and that patients are given all the appropriate advice before they decide to participate. People must be able to make an informed decision. After they receive positive results it is essential that people have appropriate support. This is often lacking when screening is haphazard, and not part of a proper screening programme."

She added:

"We want the public to be extremely wary of unregulated screening. People should be especially cautious about testing kits that can be bought through the Internet and mail order. The BMA is also worried that even with the existing major programmes the information about the benefits and limitations may be insufficient for patients to make an informed choice based on the harms and benefits of taking part."

Population screening and genetic testing recommends that the Government addresses the issues of unregulated/ad hoc screening, improves information available about formal screening programmes and works with the Association of British Insurers to ensure that genetic screening does not unfairly discriminate against people3.

The report outlines some of the benefits and potential harms associated with screening. Benefits include:

� early detection and successful intervention for diseases that are hard to treat once symptoms arise;

� identification of risk so that preventative measures can take place;

� control of diseases at population level;

� identification of carrier status for genetic mutations to allow for informed family planning.

Harms include:

� falsely positive results in people without disease, leading to invasive and potentially dangerous further investigations;

� falsely negative results in people with the disease, leading to inappropriate reassurance and possible delayed diagnosis if symptoms are then ignored;

� over-detection of latent disease, leading to treatment with possible side-effects for conditions that would not have caused a problem;

� impact on relatives for individuals with inherited disorders detected by screening.

1 Full name of report: Population screening and genetic testing - A briefing on current programmes and technologies.
2 Formal screening programmes are those with clear national policy, based on sound evidence and with explicit quality standards and quality assurance mechanisms in place. For example, national programmes include:

� the NHS breast screening programme

� the NHS cervical screening programme

� antenatal screening

� newborn blood spot screening

� newborn hearing screening

For further details please see
3 A full list of recommendations is available on page 19 of the report.
 

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