Interview: Cassandra Coburn

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r Cassandra Coburn describes her career journey as a series of fortunate coincidences. But whether by happenstance or by design, an interest in healthy longevity, a love of writing and a desire to make a diff erence shine clearly throughout her career history. After obtaining a PhD in genetics from the Institute of Healthy Ageing at University College London, Coburn became a senior editor at The Lancet Oncology and was later promoted to deputy editor.

In 2018, Coburn left The Lancet to write a popular science book, Enough, and work as a freelancer. Just as she was starting to question whether freelancing was her true calling, a perfect opportunity arose for her to utilise her PhD and work in an area of interest. She grabbed it and in 2020 was welcomed back to The Lancet family as the founding editor-in-chief of The Lancet Healthy Longevity.

Healthy longevity

The Lancet Healthy Longevity focuses on longevity and healthy ageing research. “People are living longer than ever before, which is worth celebrating,” says Coburn. However, she adds, lifespan is not the only measure of success. “One of the things that we really wanted to explore is: how can we ensure that people have healthy longer lives, as opposed to seeing population health falling off a cliff at some point?”

Healthy life expectancy refers to the average number of years an individual can expect to live in good health. Despite its importance, there is insuffi cient research, focus and investment in this area. Coburn cites the Ageing: Science, Technology and Healthy Living report (bit.ly/3fc4TEo) published in January 2021 by the House of Lords’ Science and Technology Select Committee, which found that “people are living longer, but many of those extra years are spent in poor health.” The report also identifi ed stark inequalities in healthy longevity, weaknesses in the aged care system, and a general lack of planning and investment.

Coburn thinks that part of the problem is people’s inability to imagine themselves in their old age – a problem that is all too familiar to actuaries. “We see the idea of old age homes and

Cassandra Coburn talks to Travis Elsum about healthy longevity, diet and sustainability, and how they are connected

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poor care and so on as something that happens to other people in other futures,” she says. “That needs to change, because no one wants to live in those places.”

She is, however, optimistic about the role of science and education in improving healthy longevity. “We can take ownership of our own lives to ensure that we have a large portion of time thriving rather than worrying about our health.”

“The Lancet is fi rst and foremost a clinical group of journals, so the primary readership is clinicians and the ultimate aim is to inform medical practice,” Coburn explains, when asked about the journal’s accessibility. “However, the journal also covers areas that have broader appeal and may be of interest to actuaries, such as discussions on policy and socioeconomic factors.”

Coburn recognises actuaries’ expertise in longevity and their contribution to research. She would like to see more actuarial work in the public domain and greater involvement in multidisciplinary projects. “Perhaps more shouting is needed, because actuaries should be informing policy and driving it forward, particularly in terms of what needs to be provided in future,” she says. Here she echoes a theme of Tan Suee Chieh’s IFoA presidency – the need for greater thought leadership. Actuaries can make a range of important public contributions, such as highlighting socio-economic inequalities in life expectancy, projecting required investment in the health and care systems, helping policymakers understand implications of ageing projections, and informing the debate on the retirement age.

A diet for the planet

Coburn’s book, Enough, is based on the Planetary Health Diet (PHD), which is a research collaboration between The Lancet and the Swedish non-profi t group EAT foundation. “I wanted to take the research, which is so important, and make it more accessible,” says Coburn.

Coburn was drawn to the sustainability aspects of the PHD partly due to her love of wildlife – fostered during her nature-fi lled South African childhood – but also for the link with healthy longevity. “None of us are going to have particularly healthy, happy lives if the environment is slowly disintegrating around us,” she points out.

Our food production systems are the single biggest driver of environmental change. “This is not the same thing as climate change. Food production infl uences multiple diff erent elements of the world, called planetary boundaries,” says Coburn, referring to the environmental limits defi ned in 2009 by a research team led by Johan Rockström. “Everyone has heard of one, which is climate change. Unfortunately, that is not the only change we are wreaking on the planet.” Others include biodiversity loss, changes in land use, freshwater use, and nitrogen and phosphorous fl ows.

Diet is also a major driver of non-communicable diseases, so it is a key element in unlocking improvements in healthy longevity. Enough seeks to tackle these interconnected challenges. “In the book,

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Coburn acknowledges that there are barriers to healthy eating, and suggests that changes in rules, regulations, taxes and subsidies could help shift the balance. However, she also notes that there are misconceptions that healthy eating is unaff ordable. “It is not all about quinoa salads with mint and pomegranate. Actually, what I’m talking about is rice and beans. That’s completely healthy, accessible and delicious.”

“None of us are The impact of meat

going to have The PHD recommends we all reduce the amount of meat we eat. “We all particularly eat a lot more meat than we need to,” healthy, happy Coburn points out. “We can signifi cantly cut our consumption lives if the and still get the nutrients we need.” Meat has a disproportionate environment environmental impact. “Everyone worries about food miles, but is slowly transport accounts for just 6% of greenhouse gas emissions associated disintegrating with food production, whereas meat production accounts for 52%,” Coburn around us” says. “Livestock is also a major driver of land-use change, which in turn drives biodiversity loss and aff ects other planetary boundaries. To produce 1kg of beef protein, it takes 1,640m2 of land – compared to 20m2 for soybeans, the main constituent of tofu.” In terms of health eff ects, Enough explains that the International Agency for Research on Cancer (IARC) has classifi ed processed meat as Category 1 – meaning it is carcinogenic to humans – and red meat as Category I take a planetary boundary and I take a food group and explain how 2A (probably carcinogenic). However, Coburn stresses, “it is not they interact.” that meat per se is that damaging – if you eat a steak, it is not like ingesting poison. It is just that the sheer quantity of meat that we Diet and healthy longevity eat now seems to be having negative eff ects.” “Without question, poorer dietary choices are driving poorer life Coburn would love to see adoption of the PHD become widespread, expectancy,” Coburn says. “The danger is abundantly clear.” For but recognises the immense challenges of population-scale example, ultra-processed foods – whose ingredients undergo many behavioural change and overcoming resistance from groups with processes during their extraction and combination – are linked to a vested interests. rising incidence of obesity and other non-communicable diseases. She emphasises the importance of assisting, rather than blaming,

Diet is also a contributor to inequality in healthy longevity aff ected stakeholders such as farmers. Rather, she suggests a gradual between socio-economic groups. Enough describes the concept of and considered approach, recalling a fi tting quote from Christina ‘food deserts’, which are typically poorer areas where residents have Figueres, former executive secretary of the United Nations limited access to aff ordable and nutritious food, meaning it is often Framework Convention on Climate Change: “This is a transition. cheaper and easier for them to eat badly. Let us be patient and impatient with ourselves.”

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Cobus Daneel and Jon Palin describe the challenges in producing the CMI’s Mortality Projections Model for 2020 A YEAR LIKE NO

The exceptional nature of mortality in 2020 is challenging for mortality projections that rely on recent experience to inform future trends. Models may need to be adapted if they are to produce plausible results. To avoid an over-reaction to one year’s data, the CMI has modifi ed its mortality projections model.

Mortality in 2020

COVID-19 led to exceptional mortality experience in 2020. Figure 1, based on the CMI Mortality Monitor (bit.ly/3scIRnI), compares standardised mortality rates (SMRs) in 2020 to those in corresponding weeks in the previous decade. (An SMR is an average mortality rate for a range of ages, assuming it has a standard age and gender profi le; this enables a consistent comparison of mortality rates over time.) As this analysis is based on registered deaths, there are dips around public holidays, when register offi ces tend to be closed.

Mortality in the fi rst quarter of 2020 was relatively low, as in 2019. The pandemic then led to a severe spike in mortality during the second quarter, before we saw record low mortality in the third quarter. The second wave of the pandemic saw elevated mortality during the winter of 2020-21, but not as high as during the fi rst wave or what the number of deaths ascribed to COVID-19 may have suggested.

Figure 2 shows mortality improvements derived from SMRs, based on the dataset used to calibrate CMI_2020 – the latest annual update of the CMI Mortality Projections Model, published in March 2021. (The working paper for CMI_2020

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FIGURE 1: Standardised mortality rates in England and Wales by week number.

3.0%

2.5%

2.0%

1.5%

1.0%

0.5%

OTHER 1 Source: CMI calculations, unisex, for ages 20-100, based on ONS provisional weekly deaths data. FIGURE 2: Standardised mortality improvements in England and Wales. 0% +8% +4% 13 26 38 KEY: 2011-2019 range 2019 2020

0%

-4%

-8% 52

IMAGE: GETTY -12%

1980 1990 2000

KEY: Annual crude improvements Range for 1980-2019

Source: CMI calculations, unisex, for ages 20-100, using the CMI_2020 dataset. 2010 2020

may be found at bit.ly/3saFxJS) These are ‘crude’ improvements, derived from the data without smoothing to separate signal from noise. The 2020 mortality improvement of -12% is well outside the range of improvements for 1981-2019, and our analysis of longer-term data from the Human Mortality Database suggests 2020 had the largest year-on-year increase in mortality since 1929.

How the CMI Model works

To ensure relevance for a variety of populations, the CMI Model models mortality improvements. Users can apply projected mortality improvements to a recent mortality table of their choice to derive projected mortality rates. In line with other ‘targeting’ models, the CMI Model interpolates between: ‘Initial’ mortality improvements, applying at the start of the projection period. These are based on recent historical mortality improvements, which are usually considered to be a good guide to short-term future improvements. ‘Long-term’ mortality improvements. As the long-term infl uences on mortality could be quite diff erent to recent infl uences, the long-term improvements are not based on historical data. As a matter of policy, the CMI does not give a view on a suitable value for the long-term rate, and users of the

CMI Model must form their own view. The model is therefore a framework for mortality assumptions – it does not give a single answer. This is important to bear in mind when setting mortality assumptions in 2021 in particular, as the pandemic may have changed longer-term mortality rates.

Figure 3 shows crude SMRs for each year since 2000, together with a smooth fi tted trend from CMI_2020. We see that, while there is some volatility from year to year, this was relatively modest for 1980 to 2019, with crude rates being

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within 3% of the trend during that period. The SMR for 2020 was well outside that range.

CMI_2020

The CMI Model ‘expects’ that the fi tted underlying trend would likely be within 3% of the crude SMR, in line with the volatility for previous years shown in Figure 3. In a business-as-usual model, the SMR in 2020 would exert signifi cant upward pressure on the fi tted trend, corresponding to a negative initial mortality improvement of about -0.7%. As the initial rate is used as the starting point for future projections, this would in turn lead to a substantial fall in cohort life expectancy.

A business-as-usual version of CMI_2020 would have led to a fall in life expectancy at age 65 of more than 10 months for females and nearly 15 months for males compared to the previous version of the CMI Model, CMI_2019. This is more than what most users would have thought reasonable, given a single year of additional data. Because of this, we have modifi ed the model to reduce the impact of experience in 2020, following a broadly supported consultation.

We have amended the smoothing process so users can place less weight on data for individual years. Specifi cally, we place no weight on the data for 2020 in the Core version of CMI_2020. This refl ects our view that mortality in 2020 was exceptional and is unlikely to be a good guide to mortality improvements in the coming years.

Other ways to cope with the exceptional mortality in 2020 were also considered, including: Increasing the period smoothing parameter – a parameter in the model that aff ects how rapidly mortality improvements can change over time.

However, to avoid excessive changes in life expectancy, the parameter would need to be increased to the extent that the model wouldn’t produce a realistic fi t over earlier periods and would almost certainly have required further tweaks in later versions of the model. Adjusting the number of deaths in the dataset to exclude those linked to the pandemic. While this seems reasonable, there could be considerable subjectivity in deciding which measure of pandemic-related deaths to use. And it would be diffi cult to argue that the resulting dataset represents a valid counterfactual of mortality in the absence of a pandemic.

Illustrative results from CMI_2020

Users of the CMI Model are required to form their own view on the long-term rate of mortality improvements, and users can apply the projections of the model to their chosen mortality table. For the purpose of illustration, we have used the S3PMA and S3PFA UK pensioner mortality tables and a long-term rate of 1.5% a year – a commonlyused value, rather than a CMI recommendation.

Figure 4 shows illustrative cohort life expectancies at age 65 on 1 January 2021 from diff erent versions of the CMI Model. It shows that CMI_2020 produces cohort life expectancies at age 65 that are about four weeks lower for males and one week lower for females than in CMI_2019, when using these illustrative assumptions for both models. The highest life expectancies shown are for CMI_2012, which are nearly 18 months higher than for CMI_2020 for both males and females.

FIGURE 3: Crude and fi tted standardised mortality rates, 1980-2020. 2.4%

2.2%

2.0%

1.8%

1.6%

1.4%

1.2%

1.0% 1980

1990 KEY: Crude Fitted trend Fitted 3% 2000 2010 2020

Source: CMI calculations, unisex, for ages 20-100, using the CMI_2020 dataset.

FIGURE 4: Illustrative cohort life expectancies at age 65 on 1 January 2021 from diff erent versions of the CMI Model. 26

25

24

23

22

21

2009 10 11

KEY: Male Female

Source: CMI calculations. 12 13 14 15 16 17 18 202019

COBUS DANEEL

is the chair of the Using CMI_2020 CMI Mortality The CMI Model is a framework that allows users to Projections project life expectancy based on their views. We Committee continue to encourage users of the model to consider adjusting the ‘core’ parameters to refl ect their views and their particular population – for example, recognising that in recent years, mortality improvements in England and Wales have been higher for those living in less deprived areas.

Responses to our recent consultation showed that, JON PALIN among CMI Model users, there is broad consensus that is secretary to the it is reasonable and pragmatic at this time to disregard CMI Mortality 2020 when assessing ‘initial’ improvements. However, Projections views may shift in time, and users can modify Committee CMI_2020 to put weight on 2020 data if they wish.

There is also an open question about the longer-term eff ects of the pandemic and what that may mean for long-term rates. Diff erent actuaries can reasonably have a range of views, and we expect some lively discussions in 2021.