UK experts call for national system to evaluate diagnostic tests

A national system should be introduced to evaluate diagnostic tests for use by the NHS, a report published this week recommends. It warns that currently no process is available for deciding which of the rapidly growing number of new tests should be used.

Such an evaluation system should extend to tests and scans aimed at people who are well, making information available to the public to warn them that many of these tests are not useful and can be harmful, according to a second report.

The first report, The Evaluation of Diagnostic Laboratory Tests and Complex Biomarkers, notes that about one billion laboratory tests are performed each year in the United Kingdom. “NHS laboratories have sophisticated systems to ensure the analytical accuracy of the tests, yet no system is in place to ensure the clinical effectiveness and utility of individual tests,” warned Peter Furness, consultant histopathologist at the University Hospitals of Leicester, vice president of the Royal College of Pathologists, and one of the report’s authors, together with representatives from the Foundation for Genomics and Population Health.

The group recommends that a new national body should be set up to evaluate diagnostic tests, with a publicly accessible database to provide evidence of performance and usefulness. They acknowledged that the National Institute for Health and Clinical Excellence, the body that evaluates technologies for use by the NHS, is unable to assess the wide range of new tests now being developed—particularly based on genetic markers, such as HER2 testing for women with breast cancer to determine whether trastuzumab (Herceptin) is indicated.

The new body would evaluate the evidence for the performance of a test and make recommendations on its use in clinical practice, the report suggests. Commissioners and healthcare professionals should be encouraged to use only the tests for which sufficient evidence of clinical performance exists. Recommendations to use new tests should be accompanied by appropriate resources.

The second report, Making Sense of Testing, recommends that the independent body should also evaluate the growing range of health tests and scans, including whole body checks and blood tests for allergies, which are being marketed directly to people who are well. It notes that the market for health tests for people to use at home is now worth £99m (€130m; $199m) a year in the United Kingdom.

After reviewing screening tests, a panel of pathologists, GPs, and clinical scientists found that only a small number are worthwhile. Most cause confusion, anxiety, unnecessary trips to the doctor, and sometimes unnecessary medical procedures, they warned.

The report, commissioned by Sense about Science, an independent trust that tries to improve public understanding of science, warned that most tests designed to diagnose specific conditions are not suitable for use by people with no symptoms. They look for the presence of a biomarker, such as a particular genetic sequence, or the amount of a biomarker, such as the concentration of cholesterol. “Tests that measure biomarkers can only tell you the levels present. They do not indicate the implications this may have for your health,” the panel points out.

This also applies to full body scans, which look for physical anomalies, such as nodules in the lungs. “Just because something is present, doesn’t necessarily mean it is causing you harm,” the report says. Experience of scans comes from their use in people who have symptoms, which means that small deviations from the norm, which are often seen in healthy people, are difficult to interpret.

Professor Furness, one of the panel that developed the report, commented, “Market forces work only if consumers can judge the quality of what they are getting. But even professionals find it difficult to assess the quality and usefulness of medical tests. We need an independent system to evaluate all these tests, with its results published and easily available to everyone.”