Do primary care health checks save lives? On the face of it, it may seem like a no-brainer, and a study published today looking at UK check-ups suggests they do. Unfortunately, that conclusion may be too hasty – and we don’t yet have a definitive answer.
In some countries, such as the US, it is routine for people to have a general check-up every year. The UK is generally more conservative medically, but in 2013, the National Health Service (NHS) in England began trying to convince everyone from 40 to 74 to have check-ups every five years, with similar tests available in the rest of the UK. Now, about half of those invited take up the offer.
The process includes getting some basic healthy lifestyle advice and having several tests, such as blood pressure and blood sugar tests, so that people can be offered medication if necessary – like statins to reduce cholesterol.
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at the University of Oxford and her colleagues have used a massive medical database called UK Biobank to try to find out whether these health checks make a difference. They tracked what happened to nearly 50,000 people who were invited to have one and went along, comparing them with the same number who ignored their invitation.
Over the next nine years, those who got a check-up had a somewhat lower rate of several medical conditions, including dementia and kidney and liver disease, as well as a 23 per cent lower risk of dying.
The result for dementia is most surprising, as the checks are mainly designed to get people treated for heart disease and diabetes, and there is currently no drug approved for preventing dementia. It may be that the medicines to reduce blood pressure also reduce dementia, says McCracken. “These results don’t mean that the person will never get the outcome [disease] – but that the outcome is delayed,” she says. “The idea is to extend the high-quality years of life.”
But this type of study has a potential problem. The results could be skewed by the fact that people who go for health checks tend to be different from those who don’t, in various ways that make them less likely to get ill. For instance, those who attend check-ups could be better off or do more exercise.
McCracken’s team tried to account for this by matching people in the health check group to those in the control group as closely as possible, using a long list of factors such as income levels, health status and so on.
But it is almost impossible to measure and account for every such factor – particularly the fact that people who attend health checks tend to be more conscientious about their health in numerous ways. “No matter how good a job you do [in accounting for confounding factors], these differences are still there,” says at Bispebjerg Hospital in Copenhagen, Denmark.
Because of the potential for bias, the only way to know for sure whether health checks work is to do a randomised trial, where people are chosen randomly to be invited. In 2012, when Denmark was considering introducing health checks, Krogsbøll analysed the results of 15 such trials.
His team found they brought in terms of heart disease, cancer, stroke or overall deaths. As a result, Denmark canned the idea. Krogsbøll updated the review in 2019 and the conclusions were the same.
One explanation may be that the people who take up a health check invitation are already getting treatment for any risk factors, says Krogsbøll. “Treating high blood pressure obviously works. But it’s another thing to be able to find a population effect when we do screening for high blood pressure,” he says. “One of the problems with screening is that it tends to be the people who need it least who accept an invitation.”
Krogsbøll cautions that some of the trials he reviewed were quite old, going back to the 1970s, and so the treatments on offer then would have been less effective than modern ones. However, the failure to see a benefit was also seen in the , which ran until 2009.
McCracken says that these previous forms of health screening may also have been less thorough than the NHS health check, where any risk factors that emerge should be followed up at further primary care visits. “The GP [primary care doctor] is bound by NHS guidelines to follow whatever interventions are mandated by those guidelines,” she says.
The only way to know for sure would be a randomised trial of the current UK health check procedure. This could have been done when the strategy was first introduced, by rolling it out randomly in different districts at different times and comparing the results – but it is now too late to do so. That is a missed opportunity, says Krogsbøll.
BMC Medicine
