The importance of credible evidence

Statistics can convey powerful messages. Latest figures show an 8.7-year difference in life expectancy between local authorities across England, Wales and Northern Ireland. This level of inequality is widely seen as undesirable, and reducing the gap is an aspiration for the main political parties. But despite the recognition of the problem and the ambition to do something about it, the life expectancy gap remains stubbornly persistent.

Reducing the gap requires a single-minded and coordinated approach across the whole of government. Action is needed to address the risk factors that cause ill health – smoking, poor diet, physical inactivity and harmful alcohol use – all of which drive health inequalities. Progress to reduce smoking shows that change is possible. But there’s been far less improvement in other areas. This is partly because policies are politically difficult, and those proposing them may fear accusations of nanny-statism. 

Yet even if we addressed inequalities in these four risk factors, there would still be significant health inequalities in the UK. Ill health is also determined by wider factors such as education, employment, income, housing and the environments in which we live. Tackling these wider determinants of health requires more profound societal change.

Sustained effort is needed to keep health inequalities high on the agenda of political parties and policymakers. Though there is value in repeating key facts and messages, sometimes we need to reframe the issue and present the facts in different, sometimes novel, ways. We’re working with the FrameWorks Institute to design more effective ways to talk about the wider determinants of health. And through our collaboration Health Equals, we are aiming to shape a new public conversation about health and wellbeing using evidence-based campaigns.

But sometimes, in our desire to get a message across, we can trip up. BBC Radio 4’s More or Less covered our 2022 analysis, which found that women living in the UK’s most deprived areas have shorter life expectancy than Mexican women. While the facts are right, the comparison was viewed by some as problematic. On reflection, we agreed and it prompted us to do further more detailed analysis.

Similarly, there’s the claim that health care contributes only 15% to the mix of factors that affect our health. We have referenced this statistic ourselves in the past, as an argument for giving a greater priority to tackling the wider determinants of health. The claim has a sound basis, but it’s often taken to mean something it doesn’t (as we explained in a recent blog).

Let’s now turn to a more recent health inequality headline. In January, Michael Marmot’s Institute of Health Equity (IHE), claimed that inequality cut short a million people’s lives in England in the last decade. It’s a bold claim that was reported across the media, including by The Guardian and the New Statesman. It’s also a highly questionable claim.

The IHE calculated how many fewer deaths there would have been if all areas of England had had the mortality rates of the wealthiest 10% of local areas, for each year between 2011 and 2019. These deaths were summed across years to get the figure of a million. This total is essentially the difference between the real world and an idealised world where everyone lives the lives of people in the wealthiest areas. We at the Health Foundation have previously done similar calculations to illustrate the scale of health inequalities. But unless the idealised world is achievable and has some grounding in reality, the method is clever arithmetic and nothing more. 

This idealised world in the IHE’s calculations would see our life expectancy ranking rise from 25th of 38 OECD countries to 2nd, with only Japan ahead. Our health inequality gap would be smaller than in any country on earth. This is a laudable aspiration, but it is implausible. 

If we are to address our high health inequalities, we need to win over those decision makers and influencers who are not yet convinced of the need to act. Or whose solutions to these challenges are rooted in policies targeted at the individual, rather than creating the systemic opportunities for everyone to lead healthy lives. Or, even if they understand the case and means for change, do not think that this is a priority for investment now, given the current economic and fiscal outlook. Numbers are an important part of the evidence needed to make the case for change. But implausible numbers can be counterproductive, creating easy targets for those who want to dismiss the arguments. 

There is now greater awareness of health inequalities, the injustices they cause and their wider economic and societal impact. Organisations that have traditionally focused on the economy – the Treasury, OBR and large consultancies – are increasingly recognising that there is no wealth without health. This creates an unprecedented opportunity to get health inequalities at the centre of government’s agenda.

We must seize this opportunity. But, in pushing for effective, evidence-informed policies to address health inequalities, it’s even more important the numbers and headlines we use are strong, impartial and stand up to scrutiny. Something for us all to consider.