most health checks are designed to look for risk factors or early signs of diseases\u00a0\u2013 the two most common being heart disease or cancer. A\u00a0quarter of premature deaths are caused by cardiovascular disease (heart attacks and strokes) and an estimated 50-80% of them are preventable. So any checks that could help early detection are surely a\u00a0good\u00a0thing.\r\nDr\u00a0Matt Kearney, a GP and the national clinical director for cardiovascular disease prevention, welcomes the growing trend for people to take control of their own health, but he says that the challenge is judging which tests are likely to do more harm than good. \u201cWe should democratise health information so everyone has access to it; doctors need to welcome people knowing more and help them to navigate options. Screening is attractive to individuals who look for reassurance that they\u2019re\u00a0healthy.\u201d\r\nThe NHS offers a\u00a0health check every five years\u00a0to everyone aged between 40 and 74 to pick up early signs of stroke risk, diabetes, dementia, and heart and kidney disease. Kearney says there is a\u00a0clear rationale for these checkups, despite criticisms that they pander to the worried well, are a\u00a0waste of resources and lack clear evidence of effectiveness. \u201cWe don\u2019t have evidence of long-term benefits yet,\u201d he says, \u201calthough initial reports are encouraging. However, the tests and interventions in the NHS checkup are all evidence-based. The alternative would be to do nothing\u00a0\u2013 but we have an epidemic of preventable ill health, such as diabetes, so we need to do something\u00a0now.\u201d\r\nThe scale of undetected conditions such as high blood pressure is enormous. The\u00a0British Heart Foundation\u00a0estimates that seven million UK citizens have undiagnosed high blood pressure, increasing the risk of heart disease or a\u00a0stroke. Kearney says that, of the 1.5\u00a0million adults in England who have taken up the NHS health check, one in 27 were found to have high blood pressure of which they were previously unaware. Of course, the next step is to make sure that, once detected, it is treated; 40% of people with diagnosed high blood pressure don\u2019t achieve optimal targets. But better detection and treatment could prevent an estimated 14,500 strokes and 9,710 heart attacks in England over the next three\u00a0years.\r\n\u00a0\r\nThe risk factors that commonly available checks are trying to identify are high blood pressure, poor diet, high cholesterol, obesity, smoking, alcohol and drugs, poor kidney function, lack of exercise and air pollution. To help achieve this, and improve uptake, Kearney wants the standard NHS health check to be available in public places, such as leisure and shopping centres and for pharmacists and a range of healthcare professionals to be on hand if tests flag up problems. Then there are national screening programmes for early detection of cervical, breast and bowel cancer, as well as aortic aneurysms.\r\nBut what if you are too young or too old for the NHS check\u00a0\u2013 or have worries, but have been checked recently? And what about rarer conditions, such as thyroid cancer or brain tumours? Should people who worry about these go for a\u00a0full MOT, complete with whole body scan, blood tests, lung function and heart tests? Then, too, there are the \u201cgender-specific tests\u201d \u2013 ovaries and breasts for women, testes and prostate for men?\r\nIn fact, men are often offered a\u00a0blood test to detect prostate problems\u00a0as part of a\u00a0health check and are told that it can be an indicator of cancer. But\u00a0Prof\u00a0Timothy Wilt\u00a0of the University of Minnesota\u2019s medical school says that\u00a0he wouldn\u2019t recommend it: \u201cAt best, the benefits are small and the risks are considerable.\u201d\u00a0Two big trials\u00a0have shown\u00a0no reduction in deaths\u00a0from prostate cancer picked up at\u00a0screening.\r\nThe idea of a\u00a0whole body scan\u00a0is attractive; Oprah Winfrey\u00a0kickstarted a\u00a0rush 17 years ago\u00a0when she had one. But\u00a0Prof\u00a0Gilbert Welch\u00a0of the Dartmouth Institute in the US is wary.\u00a0In a\u00a0study of more than 1,000 healthy middle-aged adults, whole body scans uncovered an average of 2.8 abnormalities each. More than a\u00a0third of them needed a\u00a0follow-up. \u201cScreening scans can trigger a\u00a0cascade of events that ends in surgery,\u201d says Welch. \u201cPeople need to be very aware of what they\u2019re getting into. The human body is full of abnormalities, modern imaging is very sensitive and we don\u2019t know how to interpret everything we see.\u201d\u00a0A study by Welch\u00a0has found that regions of the US with higher rates of routine\u00a0\u2013 often unnecessary\u00a0\u2013 scanning have higher rates of nephrectomy (surgical removal of a\u00a0kidney.) He thinks the two are\u00a0connected.\r\n\u201cWhole body scanning can unearth a Pandora\u2019s box of \u2018incidentalomas\u2019 \u2013 spots on your liver, lungs, adrenal gland, thyroid gland, ovary, pancreas and kidney. We doctors aren\u2019t sure what they mean, so we tend to investigate them\u00a0\u2013 an investigation that typically involves getting tissue, which requires needles and other surgical procedures. Whether anyone is helped by the process is hard to know, but it is easy to see how they can be harmed: unnecessary anxiety, unneeded surgical interventions and their attendant complications, including, rarely, death,\u201d says\u00a0Welch.\r\nBut what about stories of perfectly well people who go for a\u00a0brain scan, find they have an aneurysm (bulging, fragile blood vessel), have an operation to clip it and avert a\u00a0possible stroke? Surely that\u2019s something you would fork out for. But\u00a0Dr\u00a0Margaret McCartney, a GP who presented a\u00a0BBC radio documentary on screening, points out that increasing diagnosis may not result in better outcomes. The prime example is a\u00a0mass screening programme for thyroid cancer in South Korea\u00a0that detected 15 times more cases than previous tests, with no net improvement in death rates from the disease to date. If everyone were scanned for aneurysms, around 2% of people would be found to have one \u2013 but, since most would never cause problems, intervention might well do more harm than good.\r\nMcCartney says: \u201cIf a\u00a0screening test is cost-effective, the NHS is doing it. We don\u2019t have evidence for additional tests at the moment.\u201d She thinks that people don\u2019t get adequate information about the potential hazards of some commercially available tests; the stress and anxiety, false positives (when a\u00a0test suggests an abnormality that turns out to be nothing) and false negatives (when a\u00a0test is reported as OK, but isn\u2019t, giving a\u00a0false sense of security). The false positives get handed back to the NHS to deal with, which is \u201cfundamentally unfair, immoral and\u00a0unethical\u201d.\r\nKearney, though, says people should make their own choices about what they want to check out. And anyone with new, unexplained or worrying symptoms, a\u00a0family history of a\u00a0particular condition or a\u00a0particular health concern should always see a\u00a0healthcare professional, whether they have had a\u00a0health check or not. The expert consensus seems to be: go ahead with commercial checks if you want to\u00a0\u2013 but buyer beware, and very\u00a0aware.