Medicine is there to help you and having screening and treatment is a good thing, right? Well, there’s a growing body of scientific concern that some testing is ‘over-diagnosing’ patients – that is, finding medical problems that may never cause harm, but can lead to an unnecessary diagnosis and avoidable distress. But we also know that many lives are saved by early detection and appropriate treatment, so here is an introduction to the debates around screening programmes.
What is screening?
NHS screening programmes proactively approach millions of individuals through direct mail to ask if they would like to be tested for one of a range of serious diseases. The individual receiving the invitation has almost certainly not been worried enough about the disease to approach their GP about it already.
Screening is proactive and is different from health promotion activities which advise people through adverts or general advice to improve lifestyle but don’t write to individuals in their homes. It is also different from health care, where a person approaches the health care system themselves.
Screening programmes in the UK (unlike most of the world) also promise to offer and guide people through the whole programme - test, information, referral to health services and treatment and care for those who need it.
There is an extra duty to make absolutely sure the programme is of the highest possible quality and done to the best standards because the offer from the NHS is proactive. After all, the person didn't ask for the screening themselves and if the process causes them some harm, then they have reason to be annoyed or alarmed.
Because so many people are tested in screening programmes and tests, however good, are never perfect, some people will be falsely reassured by negative tests when they do have the disease. Others will be told they are positive for a disease when they don’t have it (false positives). This can cause unnecessary anxiety and lead to further tests, treatment and worry.
It is because such programmes can do harm as well as good that the decision to start and run a screening programme is subject to the highest level of scientific and public scrutiny. Any new proposals are widely publicised and consulted upon by experts and the public before being implemented.
The UK National Screening Committee (UK NSC) is the national body that was set up in 1996 to oversee population screening in the UK, and in April 2013 we became part of PHE. The UK NSC’s role is to make recommendations to the four UK Governments about health screening and, in England, to implement evidence-based screening programmes that do more good than harm.
Based on UK NSC recommendations, screening programmes for a number of different conditions have been established. There are currently three national cancer screening programmes: breast, bowel and cervical; and eight non-cancer screening programmes: six antenatal and newborn (Fetal Anomaly, Infectious Diseases in Pregnancy, Sickle Cell and Thalassaemia, Newborn and Infant Physical Examination, Newborn Blood Spot and Newborn Hearing) and two young person and adult (Abdominal Aortic Aneurysm and Diabetic Eye).
PHE has brought together the teams responsible for implementing the cancer and non-cancer screening programmes and we all now sit in PHE’s Health and Wellbeing directorate. This enables us to share knowledge and experience much more easily, as well as providing us with a real opportunity to benefit from the joint skills and expertise PHE holds in early prevention and immunisation to improve screening services.
The reason why we recommend screening for some conditions and not for others is based on solid evidence. This is perhaps best demonstrated using a couple of examples.
One to two children in every 1000 are born with a hearing loss in at least one ear, often into a family with no history of hearing problems. The Newborn Hearing Screening Programme offers parents the chance to have their baby’s hearing tested within two weeks of birth.
In 2011-12, of almost 700,000 babies screened, 1,167 children benefited from early identification of hearing loss and were able to receive the appropriate treatment before six months of age develop better language and communication abilities.
Given the simple, non-invasive nature of the screening test and the clear benefits of early detection, the case for a national screening programme is clear.
On the other hand, for a condition like prostate cancer the evidence does not currently support the implementation of a national screening programme.
The test for prostate cancer is not effective enough and does not identify a large proportion of men who in fact have prostate cancer. A positive test will lead in most cases to a biopsy, which often does not give a definitive answer and leads to anxiety and to further investigations.
Current research indicates for every 100,000 men at age 50 offered screening, 748 would end up being treated. The men accepting screening would have their lives extended on average by a day – while 274 men would be made impotent, 25 incontinent and 17 would have rectal problems as a result of the treatment.
I hope that research into new, more accurate tests for prostate cancer yields results and that in the not too distant future the UK NSC can wholeheartedly support screening. For conditions like this, it is better to think of us saying “not yet” to screening rather than “no”.
As I mentioned earlier, it is our job to monitor all the existing evidence, weigh up the harms versus the benefits and recommend what conditions the UK population should be screened for.
103 different conditions, from Alzheimer’s to syphilis, are reviewed on a consistent, structured and transparent basis and assessed against a set of 22 internationally recognised criteria. These cover the condition, the test, the treatment options and the effectiveness and acceptability of the screening programme. Broadly, those that meet the criteria are recommended for screening and those that don’t are not. Conditions are usually reviewed once every three years, though we will start a review early if major new evidence emerges in the interim. We announce our latest recommendations at our committee meetings three times a year.
In this blog I have just touched on some of the issues surrounding screening and tried to explain some of our considerations in what is a complex area. Can you think of any other conditions where a national population screening programme would do more harm than good? There is a whole host of further information on what screening is and how it works available at our website to give you food for thought.