Big discontinuities are fascinating. Just when we think we understand something, the trend line changes radically. Examples of unexpected discontinuities in trends include the massive decline in smoking among African-Americans in the 1980s ; the drop in crime in high-income cities over the last decade or so ; and the recent drop in teenage pregnancy rates. These are favourable trends in contrast to the sudden end of year on year decline in mortality among the majority population in one large country – white people in the US. Anne Case and Angus Deaton drill down into the numbers in their recent paper:
- Is this trend confined to white people? Yes, black and Hispanic people continue to experience declining mortality rates.
- Is this trend seen in other high-income countries? No – in France, Sweden, Japan and the UK, age-specific mortality continues to decline across the populations.
- How does it differ among whites by economic class? Using education as a proxy, a decline in life expectancy is confined to those with no education beyond high-school.
- What diseases are driving it? ‘Deaths of despair’ (suicide, alcoholic cirrhosis, drug overdose) are rising among white people in the US in absolute terms, and in comparison with non-white groups and with other countries. Cardiovascular deaths are no longer declining among whites in the US, even as they continue to do so in other countries. Increases in ‘deaths of despair’ along with arrest in declining cardiovascular diseases, combine to extinguish the declining trend.
- Is the phenomenon localised geographically? No, the ‘epidemic’ in ‘deaths of despair’ among white people covers rural and urban areas, and has pretty much become country-wide.
- Is the problem gender specific? No, the rise in ‘deaths of despair’ among the less-educated group affects both women and men.
- What are the long term trends? While the differences in mortality between better and less well educated groups are getting narrower in Europe, the gap is getting wider among whites in the US. This widening gap is also reflected in changes in self-assessed health.
So is all this really just a reflection of widening economic disparities? No:
- Disparities are widening within the black community and between black people and white people. However, mortality is converging between rich and poor black and Hispanic people, and ‘deaths of despair’ are not increasing in these ethnic groups.
- Widening disparities are seen in all comparator countries – in Spain, ‘deaths of despair’ actually declined through a vicious economic downturn between 2007 and 2011, for example.
- The difference in outcome correlates much more strongly with change in education than change in income.
- Historically there are many instances when mortality and inequality have moved in different directions, and selective reporting can be used by unscrupulous ideologues to buttress either side of this argument.
So why has it happened. Here we need to turn to sociology (in some desperation). A novel, called ‘Fishtown’ (by Neal Goldstein) captures some of the sociology; a tale of a rising feeling of purposelessness as workers overseas and machines at home combine to force less educated people (men especially) out of jobs. Such people rely on welfare, while immigrants take over the lowest paid jobs. Another explanation turns on the idea of differentials – this time between whites and non-whites, and loss of status rather than failure to achieve it – “if you have always been privileged, equality begins to look like oppression.” Case and Deaton are careful to point out that the above explanations are not strongly supported by the data. But there is something ‘out there’ – a ‘latent variable’ with a long memory (i.e. operating over the life course of various ‘cohorts’ of people). Many commentators pretend they have understood these latent variables, but I think we are going to have to look a lot harder and resist the beguiling but facile explanations offered up by journalists, political commentators, and academics alike (a point pursued in the next exciting instalment of your News Blog).— Richard Lilford, CLAHRC WM Director
- Oredein T & Foulds J. Causes of the Decline in Cigarette Smoking Among African American Youths From the 1970s to the 1990s. Am J Public Health. 2011; 101(10): e4-14.
- The Economist. Falling crime. Where have all the burglars gone? The Economist. 20 July 2013.
- Wellings K, Palmer MJ, Geary RS, et al. Changes in Conceptions in Women Younger Than 18 Years and the Circumstances of Young Mothers in England in 2000-12: an Observational Study. Lancet. 2016; 388: 586-95.
- Case A, & Deaton A. Mortality and morbidity in the 21st century. Brookings Papers on Economic Activity. BPEA Conference Drafts. March 23-24, 2017.
When we think of risk factors for mortality we properly think behaviours (e.g. smoking / obesity) or genetics (e.g. family history). What about psychological factors – can unhappiness increase your risk of risk of cancer? Well, Batty and colleagues  have tackled this problem as follows:
- They assembled 16 prospective cohort studies where behaviours and psychological state had been measured and in which participants were followed up to see if cancer developed.
- They obtained the raw data and obtained an individual patient meta-analysis.
- They adjusted for the usual things known to increase risk of cancer (obesity, smoking, etc).
- They calculated relative risk of cancer according to antecedent psychological state.
They found a positive correlation between psychological distress and risk of cancer. But causality might have run the other way – (occult) cancers may have been the cause of psychological distress, not the other way round. So:
- They ‘left censored’ the data, thereby widening the gap between the point in time where the psychological state was measured and the point where cancer supervened.
The association between psychological state and cancer death persisted, even when they were separated by many years. What is the explanation?
- Failure to fully control for all behaviours (although behaviour could be the mechanism through which the cancer risk is increased in people with depression, in which case they ‘over-controlled’).
- Reduced natural killer cell function.
- Increased steroid levels, which can apparently affect DNA repair in some way.
- Some mechanism yet to be discovered.
In any event, the findings are intriguing, for all that practical implications may be limited.
— Richard Lilford, CLAHRC WM Director
- Batty GD, Russ TC, Stamatakis E, Kivimäki M. Psychological distress in relation to site specific cancer mortality: pooling of unpublished data from 16 prospective cohort studies. BMJ. 2017; 356: j108.
An overview of this topic in the New England Journal of Medicine caught the eye of the CLAHRC WM Director. A very short summary:
- Evidence that e-cigarettes are better than other pharmacological products in assisting people with quitting is not compelling according to the authors.
- The subject is hard to pin down because there are over 400 brands each of a different chemical composition.
- Compared with tobacco smoke, e-cigarette vapour is almost certainly less toxic.
- E-cigarette vapour contains many known toxins, such as formaldehyde and acetone. So it is more toxic than air.
Should they be banned? Certainly not. Should a product warning that the health effects are unknown and there is a material risk be mandated? Certainly.
— Richard Lilford, CLAHRC WM Director
- Dinakar C & O’Connor GT. The Health Effects of Electronic Cigarettes. New Engl J Med. 2016; 375: 1372-81.
If you smoke, you increase the risks of certain multi-factorial diseases five- to ten-fold. But various genetic variations carry much smaller risks for these diseases thanks to evolutionary pressures. So why would a person want to know their genetic risk? Smokers should quit even if their genetic risk is low. And non-smokers should continue to abstain, even if their genetic risk is low. Consistent with this observation, a recent BMJ article shows that knowledge of one’s genetic risk does not influence a person’s behaviour. The point in continuing research into genetic associations is to unravel pathophysiological mechanisms on the assumption that this knowledge will translate into better treatments for established diseases. Precision medicine, it seems, does not entail precision preventive medicine.
— Richard Lilford, CLAHRC WM Director
- Hollands GJ, French DP, Griffin SJ, et al. The impact of communicating genetic risks of disease on risk-reducing health behaviour: systematic review with meta-analysis. BMJ. 2016; 352: i1102.
The Global Burden of Disease study is an extraordinary collaborative effort to document the health of the human race. It produces a series of weighty publications every four years, packed with interesting detail. The most recent set of papers have been published and the first deals with life years lost. The study documents the recent epidemiological transition in which non-infectious diseases have taken over from infectious diseases as the main cause of life-years lost across the world. Childhood malnutrition is no longer enemy number one, relegated to fourth place globally, but it retains the number one slot in sub-Saharan Africa. High blood pressure, smoking and obesity now occupy the first three slots globally. CLAHRC Africa includes a programme of research on salt. Salt is now enemy number two, after smoking, in unhealthy behaviours. Research into methods to reduce salt intake is a priority, even as the debate continues into whether sodium levels can fall too low – some data suggest a J-shaped distribution of risk with rising salt intake. Unsafe sex is the major risk factor in East, and Southern Africa, while South Africa is the country with the world’s highest burden of disease associated with reversible environmental factors. Areca nut (another interest of CLAHRC Africa) does not make it onto the list. Along with smokeless tobacco, the CLAHRC WM Director thinks this risk should be considered for inclusion in further versions. Another criticism is double counting – high sodium intake and high systolic blood pressure both appear on the list, yet the former is a prominent cause of the latter. To be fair, the authors do recognise this issue. In a future blog we will report on a further analysis of the remarkable GBD dataset to consider not just the deaths, but the total burden of disease (for instance in Disability Adjusted Life Years [DALYs]).
— Richard Lilford, CLAHRC WM Director
- GBD 2013 Risk Factor Collaborators. Global, regional, and national comparative risk assessment of 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks in 188 countries, 1990–2013: a systematic analysis for the Global Burden of Disease Study 2013. Lancet. 2015; 386: 2287-323.
Tobacco control policy was the topic of John Britton’s Cochrane lecture at the Annual Scientific Meeting of the Society for Social Medicine this year. The lecture noted that the UK is the highest ranked European country in terms of its policies, yet failed to achieve the low smoking rates of Sweden, which is only ranked mid table for policy. This is likely due to a large number of smokers in Sweden switching to using snus, an oral tobacco product. Snus, which is banned in the UK, has a much lower risk of causing severe tobacco related disease than smoking. Thus, while the numbers of nicotine users in Sweden is not remarkably low, the harm caused by such use is. A similar debate now focuses on e-cigarettes.
I was reminded by this lecture of David Nutt’s discussion of the purposes of drug control policy. Nutt, the former head of the Advisory Council for the Misuse of Drugs, argues that policy makers focus on reducing the prevalence of drug use but that they ought to be focused on harm reduction instead. For example, causing the price of a drug or alcohol to rise, through prohibition or taxes, may reduce use among recreational low risk users but may have little effect on those with problematic use or lead them to switch to potentially more harmful drugs or products with lower prices (e.g. ).
E-cigarettes have become embroiled in a heated debate. The scientific discussion has intertwined with the political one. Some evidence suggests that it is less harmful than smoking and may reduce smoking prevalence and therefore harm from nicotine use. Nevertheless, the validity of this evidence, and the conflicts of interests involved – much of the research has been funded by both anti-tobacco groups and e-cigarette manufacturers – have been brought into question. For example, a row emerged recently after a paper in the NEJM showed that e-cigarettes can produce dangerously high levels of formaldehyde, yet this is only at temperatures not typically produced through normal e-cigarette use. A number of critics argued that the paper “was so misleading it should be retracted.” However, there has been suggestions of potential conflicts of interest of both authors and critics. Nevertheless, while this paper is of potential scientific interest, it may not be of much use in formulating e-cigarette policy.
The e-cigarette debate shows no sign of abating soon. We agree with McKee and Capewell who say, ““directors of public health and the wider community desperately need advice on EC [electronic cigarettes] that is evidence-based and free from any suspicion of influence by vested interests”. Indeed, no public health decision should turn on the basis of intuition alone.
— Sam Watson, CLAHRC Research Fellow
- Joossens L & Raw M. The Tobacco Control Scale 2013 in Europe. Sixth European Conference on Tobacco or Health. Istanbul, Turkey, 26-29 March 2014.
- Nutt D. Drugs: Without the Hot Air. 1st Edition. Cambridge: UIT Cambridge Ltd. 2012.
- King L. Evidence based policy? Why banning mephedrone may not have reduced harms to users. 19 September 2011.
- McKee M & Capewell S. Evidence about electronic cigarettes: a foundation built on rock or sand? BMJ. 2015;351:h4863.
- Jensen RP, Luo W, Pankow JF, et al. Hidden Formaldehyde in E-Cigarette Aerosols. N Engl J Med. 2015;372:392–4.
- Bates CD & Farsalinos KE. Research letter on e-cigarette cancer risk was so misleading it should be retracted. Addiction. 2015;110:1686–7.
- Willingham E. Researchers call for retraction of NEJM paper showing dangers of e-cigarettes. 11 September 2015.
Two recent studies have considered the effect of smoke-free legislation bans on perinatal and child health. The first looks at smoke free legislation in England. Their interrupted time series documents an immediate drop in stillbirths, low birth weight, and neonatal mortality following introduction of the legislation in July 2007. Interestingly, sudden infant death rates showed no change, perhaps because parents already avoided smoking at home?
The second paper is a systematic review of smoking bans in work places and/or public places, and at least one measure of health. Eleven studies were identified, all interrupted time series. Again smoke free bans were associated with reductions in pre-term birth and hospital attendance for asthma, but this time no effect on birth weight was noted. The CLAHRC WM Director fancies himself as a libertarian. The limit on personal liberty is maternal risk of physical harm to others. He therefore supports smoke-free legislation.
— Richard Lilford, CLAHRC WM Director
- Been JV, Mackay DF, Millett C, Pell JP, van Schayck OCP, Sheikh A. Impact of smoke-free legislation on perinatal and infant mortality: a national quasi-experimental study. Sci Rep. 2015;5:13020.
- Been JV, Nurmatov UB, Cox B, Nawrot TS, von Schayck CP, Sheikh A. Effect of smoke-free legislation on perinatal and child health: a systematic review and meta-analysis. Lancet. 2014;383:1549-600.