Epidemiology in the age of sustainable development

The improvement of population health is one of the signal achievements of modern life and one of the greatest challenges in the coming generation. The centrality of good health to well-being is expressed in the global recognition of health as a basic human right1 and in the new Sustainable Development Goal (SDG) 3,2 to ‘ensure healthy lives and promote well-being for all at all ages’. Epidemiology stands at the core of this great goal and opportunity. In the coming generation, epidemiology will grapple with several unique challenges and will be able to draw upon several cutting-edge technologies. As the editor of this journal, Stephen Leeder, recognized a dozen years ago in his monograph A Race Against Time,3 global population trends—notably worldwide ageing—portend an epidemic of non-communicable diseases. This fact is acknowledged in SDG Target 3.4 calling for a reduction by one-third of deaths from non-communicable diseases.2 Yet this is not all. Humanity faces potentially catastrophic risks from a range of escalating environmental threats. The most dangerous, of course, is climate change which threatens population health through massive heat waves, extreme droughts, famine, extreme storms and floods, and forced migration. Less recognized but similarly threatening is the mass conversion of habitat and loss of biodiversity, which threaten to upend global food systems and promote emerging and re-emerging infectious diseases (such as MERS, Zika, Ebola, SARS, to name just a few). The rapid urbanization of the developing world, which promotes sedentary lifestyles and reliance on industrially processed foods high in sugar, processed meats and grains, and unhealthy types of fats, is already producing the epidemics of obesity, adult-onset diabetes and cardiovascular diseases. The continued heavy reliance on coal as source of energy, especially in Asia and Eastern Europe, contributes to massive burdens of respiratory and other diseases. Social and environmental threats will interact in complex and non-linear ways. Climate scientists have noted how the extreme drought in Syria during 2007–10 provided the tinder for the eruption of protests in 2011 that in turn led to a disastrous regional war, with around 500 000 dead and 10 million displaced.4 In a world of 7.5 billion people, likely to be about 9 billion before mid century, the risks of poverty and environmental shocks turning into mass migration and then to violence are very great. In an era of profound change and threat, epidemiology stands as the foundation of our public health response, providing the rigorous data, modelling and analytics to identify and anticipate disease burdens at population scale. Epidemiology itself must become global and systemic, meaning in particular that the big data generated by our information-rich global society should be systematically harvested and harnessed for insights and warning signs regarding public health. The Global Burden of Disease programme led by Dr Chris Murray has demonstrated the immense value of systematic local-to-global-scale health metrics.5 The INDEPTH programme, described in the editorial by Sankoh and colleagues in this issue, is another such breakthrough.6 With the advent of the SDGs and the global commitments on climate change, biodiversity and disaster risk reduction, we have the opportunity as well as the urgent need to scale up the investments in cutting-edge epidemiology. This should include the following. First, every country should increase efforts to mobilize cutting-edge information and communications technologies (ICTs) to record accurate and comprehensive vital events, to identify causes of death (including through ‘verbal autopsies’ in low-income rural areas), and to survey communities for emerging and re-emerging diseases in real time. If Ebola had been identified earlier in the 2014 outbreak, the epidemic could have been halted much sooner, with many fewer deaths. Second, epidemiologists should work together with front-line health workers and information systems engineers to ensure that data systems not only serve patients and providers in real time, but also capture the data into epidemiologically useful population-scale data. The breakthroughs in biometric unique identification (ID) systems (such as India’s Aadhaar system7) should enable the rapid inscription of literally billions of people in health informatics systems in the coming generation. Third, epidemiologists should be trained in the broader dynamics of global systems change to anticipate the roles of climate change, habitat loss, water stress, pollution, lifestyle changes, dietary patterns and other social determinants of health (including substance misuse, depression, unemployment, forced migration, social exclusion, ageing and loneliness, and so forth) in what is likely to be a rapid change of disease burden, including many new and major challenges. Many countries currently train too few epidemiologists. The global scale-up of well-trained epidemiologists must be part of the SDG agenda, and the new generation of epidemiologists should be trained to work across disciplines with social scientists, earth-system scientists, information engineers and others, to maximize the remarkable potential of the field. The future public health risks are real and even dire, but the opportunities are at least as great. Building on epidemiology and advances in clinical care, the Millennium Development Goals (MDGs) helped to usher in a massive scale-up of prevention and treatment of micronutrient deficiencies, infectious diseases and unsafe pregnancy and childbirth. Although there is much to be done, the deaths of children under the age of 5 years fell from 12.7 million in 1990 to 5.9 million in 2015 through the deployment of appropriate interventions such as vaccines, antibiotics and insecticide-treated bed nets, supported by continuing technological advances.8 With focused strategies and adequate financing for public health, the world can achieve even more in the SDG era. By fighting climate change, protecting biodiversity, cleaning the air and water and improving diets, we will prevent a massive burden of disease. By deploying existing but under-used medical interventions against cardiovascular diseases, mental illnesses, some cancers and other non-communicable diseases, we can significantly improve public health and longevity. By continuing innovations in vaccines, diagnostics, therapeutics and curative medicines, imaging, and other technologies, we can achieve breakthroughs in a widening range of communicable and non-communicable diseases. It will be the shared responsibilities of government, academia, business and civil society to translate those advances into population-scale care with speed and equity. Adequate global and national funding for public health, including epidemiology, will be essential. Accurate and timely data will be vital for service delivery, epidemic surveillance and government accountability. Close collaboration of all stakeholders will be vital. Success will depend on a sound scientific base, grounded in the rigours of epidemiology. It is fitting, therefore, that the International Journal of Epidemiology begins a new editorial era in line with the new era of sustainable development. The challenges are enormous; the opportunities within reach are even greater.