What is screening?
Screening tests try to detect hidden or early disease in people who are well and who have no symptoms at all.
If you have a symptom, like a breast lump, or an odd looking mole, or problems with headaches, you need diagnostic tests, not screening tests. This information about screening tests on this website is for people who are well and who have no symptoms.
The idea of screening is to find abnormalities which can be treated more easily than the disease that they can lead to.  However, no screening tests are perfect. Some screening tests are very good, accurate tests which  can be useful in preventing or reducing later disease. However other screening tests can do more harm than good.

This means that it's important to balance the pros and cons of tests with reliable information so that you can decide whether you want to have them done or not. Many screening tests are done within the NHS and have been approved by the UK National Screening Committee. This organisation examines the balance of risk and benefit and makes recommendations about what the NHS should provide.

Information given about screening tests in the NHS is currently under review. This is because it has been criticised by doctors and patients who are concerned that the pros and cons aren’t being set out objectively. Screening tests are also available outside of the NHS. These are of many types, ranging from blood tests to body scans. Many of these are not approved by the UK National Screening Committee. Some of these tests have been researched and found to create more harm than good. This website aims to highlight the need for unbiased information to be made available to people who are considering screening tests within the private sector.

Click on the links below to see some of the reasons we are worried about private health screening tests:
Many good ideas - or seemingly good ideas - in medicine simply don't work in practice. So it's very important to test ideas and make sure that they work and that tests do more good than harm. So, for example, there is good evidence that testing babies for rare genetic conditions a few days after birth - the 'heelprick' test - diagnoses the condition accurately and means treatment can be started that dramatically reduces the chances of long term disability. This idea has been well tested and has worked. So it is used throughout the NHS. It’s different, however, with other screening tests that sounded good  - like PSA screening for prostate cancer. For many years doctors believed that this allowed men to be diagnosed with prostate cancer earlier. However it has been shown that many prostate cancers are treated when there was a very low risk that they would go on to cause invasive cancer. The side effects of surgery can be severe - incontinence and impotence - and so the cons outweigh the pros. Many doctors who thought the test was useful have now changed their mind. One of the reasons why it took so long to find this out was that the PSA screening started well before any randomised controlled trials. This kind of fair test means that the people who have screening and people who don't can be compared. It's the fairest test to do when you want to find out if screening works or not.
False positive tests happen when the test appears to indicate a problem but the test is later shown to be wrong. For example, a cervical smear test may be reported as showing abnormal cells but may be reviewed by another screener who may find it to be normal. The other problem with screening tests is 'overdiagnosis'. Essentially this means being diagnosed with something which was never going to harm or kill you. So you may end up having unpleasant or invasive tests which are unnecessary and potentially harmful. Another example is of an x-ray which appears to show a shadow. It may be difficult to tell if this is a cancer or not, and so the patient may be asked to undertake a CT scan or a biopsy. Further tests are often needed to work out whether it is a problematic ‘shadow’ or not. The tests may be uncomfortable or may even lead to further complications. There is a story related to that, here.
There are two main kinds of screening tests - scans and blood tests. But what is normal can be difficult to know. For example when people have their heads scanned, we know that we find things - lumps, bumps, irregularities - in healthy well people about 1.5% of the time. However the vast majority will not get any problems because of 'abnormalities'. The more you look for problems in well people, the more they are found. But it can be hard to know when something is 'normal' and not going to cause problems, and when something should be cut out or biopsied. For example, we know that in breast screening, many tumours, called DCIS are found, but most don't progress to invasive cancer. But because we don't know which will cause problems, all are treated the same. Some women don't mind this. Other women find the surgery traumatic and wonder if it was necessary. What's important is that you know the possibilities before you have the screening tests done to start with.
With blood tests, it is important to know that ‘normal’ is not a simple matter. For example, the level of blood glucose numbers which indicate diabetes and impaired sugar tolerance - which can be a precursor to diabetes - changes every so often and is usually decided by a medical committee. With cholesterol, there is a sliding scale of risk attached, as there is with blood pressure.
For example, liver function blood tests are often offered by private screening companies offering a ‘check up’. However, if your liver tests are all in the normal range, this doesn't give you any guarantee that you are free from liver disease. For example, we know that liver tests are normal about a third of the time even when there are cancer cells present in the liver. We also know that liver blood tests can be normal when there is cirrhosis, scarring of the liver. Or a scan may not be able to see a small cancer. False negative tests refer to a test being reported as normal when there really is a problem. No screening test can be guaranteed to be free from false negatives.
False negatives are one reason why people can be falsely reassured - because a problem was not picked up by screening. There may be other problems concerning the limits of the usefulness of screening tests. For example, it may mean that people who are doing unhealthy things - like smoking or drinking too much - may feel that 'normal' tests mean they are at low risk of future illness. In fact, lifestyle factors (smoking, weight, exercise, diet) are much better at predicting future illness than many screening tests.
Screening tests which have been found to be effective are already offered by the National Health Service. For example, Lifeline Screening offer aortic aneurysm screening. In their information leaflets they say that this can be done yearly. The NHS only offer it once in men aged 65 because this is the age group where there is more good than harm done. However it is important to note that even though it is available on the NHS, there are still pros and cons attached to it. The idea is that a swelling in the aorta, the main blood vessel in the abdomen, is detected by ultrasound before it bursts. However, not all aneurysms will burst, and the operation which is done to stop it bursting causes death around 1 in 20 times. It is therefore not to be undertaken lightly.
There is evidence that women who have a false positive test in breast screening have distress about it which may be long lasting. This area is under-researched, but many patient advocates are clear that there are side effects of screening which are not just physical.
Although it seems logical to think that the earlier a problem is caught, the easier it is to do something about it, this is not always so clear cut. It's always important to try and diagnose symptoms promptly. However it is not always the case that screening people to detect problems sooner makes a difference. For example one of the tests offered by Lifelife Screening is a carotid artery ultrasound. This is a scan to look for narrowing of the main artery in the neck that supplies blood to the brain. This is a good test to do if someone has had a stroke. But if someone has not had a stroke, it has been shown that even if you find narrowed arteries, the treatment to get rid of it causes as many problems as it could prevent.
The most important things you can do for your health are straightforward.
  • Don't smoke
  • Do some daily exercise
  • Eat a varied Mediterranean Diet, and mainly plants.
  • If you drink alcohol, drink in moderation and have alcohol free days
  • See people and do things you enjoy, including work
  • Keep to a healthy weight
  • Cycle if you can