CRP TEST

A simple three-minute blood test could tell doctor’s whether a patient needs antibiotics.

Not only could this help patients avoid suffering nasty side-effects from taking unnecessary drugs, but it could also tackle one of the greatest threats to modern health – antibiotic resistance. The test tells a doctor whether the patient is suffering from a viral or bacterial infection – that way, they will know whether or not to prescribe antibiotic medication.

Antibiotics are only effective against bacteria – they do not kill viruses. Currently, the type of infection can only be confirmed with a blood test which must be analysed in a laboratory, a process that can take two to three days.

GPs say they often give antibiotics as a full-safe measure, and that patients pressure them for the pills. According to Public Health England (formerly the Health Protection Agency), if patients ask their doctor for an antibiotic, the vast majority will get one.

Over-prescribing of antibiotics has consequences both for the patient and the population. As well as causing side-effects, over-use can lead to bacteria becoming resistant, making antibiotics less effective at fighting infections. The Government’s chief medical officer has described this as ‘one of the greatest threats to modern health.’

Over the past five years alone, the number of antibiotic prescriptions has risen by 10 per cent to 41 million prescriptions at a cost of £170 million to the NHS. A third of all Britons have taken them in the past 12-months.

A simple finger-stick test could solve this ‘catastrophic threat’. The test – which involves taking a drop of blood from the finger – can tell doctors within three minutes whether an illness is caused by a bacterial infection which requires antibiotics, or a virus, which does not.

It measures a substance called C-Reactive Protein (CRP) in the blood. The amount of this protein increases when the body is fighting a bacterial infection, but not when it is fighting a virus, which triggers a different immune response.

So a doctor would know that if the CRP level was shown to be low, antibiotics would not be required.

Studies show that providing ‘proof’ that they are unnecessary to patients who demand antibiotics can significantly reduce the number of prescriptions.

One EU-funded study, presented at the World Association of Family Doctors conference in 2010, looked at how respiratory infections which are generally caused by viruses were treated by 600 GPs in six different countries. It found that antibiotic prescriptions fell by 25 per cent when doctors used the CRP test.

British scientists say the test could be a useful tool for significantly reducing antibiotic prescriptions.

A senior clinical research fellow at Cardiff University who specialises in antibiotic resistance in primary care, said:

… Unfortunately, it is very difficult to accurately determine whether an infection is viral or bacterial.

… Markers such as CRP have evolved to help where there is lingering uncertainty after a clinical assessment or where the patient has strong beliefs that antibiotics are needed.

… (However, not everyone needs the test) … Patients who appear very unwell should be treated with antibiotics or admitted to hospital without the test because they could develop complications.

… But for those patients where there is doubt, or where the GP feels antibiotics are not needed but the patient is putting pressure on to prescribe them, the test can be helpful.

The test is currently only available in laboratories in the UK (it can be carried out privately for around £50) because the NHS does not yet fund it in GP practices. The machine to analyse the test would initially cost £1,000 and then £3 per test.

A spokesman for the Royal Pharmaceutical Society says it is likely to be some time before the test is routinely available on the NHS.

… CRP testing would be a natural extension to the clinical services we offer but it will be two or three years before there is enough evidence for it to be made widely available.

Other concerns about the test are that the results are not always clear – levels of CRP also increase as a result of inflammation caused by other conditions such as rheumatoid arthritis as well as infections.

The test is deemed to be a guide and does not categorically imply that a patient has a bacterial infection if the results are synonymous with having an infection. It gives the doctor a number that has to be interpreted in light of the other symptoms and the patient’s overall risk profile.

For example, a doctor is more likely to treat an elderly person with diabetes with antibiotics than a young healthy person, as the elderly person is more likely to develop complications.

Clinical experts say the best way to reduce antibiotic prescriptions is to educate doctors and patients about common complaints and when antibiotics are necessary.

The Royal Pharmaceutical Society warns that to see this test as the panacea would be an extremely dangerous idea. The Society says it needs to work hard to educate patients about when it is appropriate to take antibiotics and by making sure they take them correctly as prescribed by finishing the course.

Public Health England adds:

… CRP may be useful in a small range of infections provided the test is robustly quality controlled.

… But nothing can replace taking a detailed patient history and thorough examination.