At the start of this course, Professor Ezzati told you about the major causes of mortality and morbidity in the world, and then professors [inaudible] and [inaudible] highlighted some of the most interesting trends, such as the impact of the ageing population, the dramatic changes in cardiovascular mortality and the threat of emerging infectious diseases. But what I find most remarkable about the global burden of disease is not the specifics, the relative importance of heart disease, HIV or road accidents, for example. Now, I'm interested in the huge variation between and within countries. So in this lecture, I'd like to discuss some of the major determinants of these inequalities and we'll show you the importance of the social determinants of health. Let's start with a question. In the next hour about 15,000 babies will be born across the world. How long do you think they will live? If you had to predict the life expectancy for each of these babies, what are the main things you'd want to know? Just think of two or three things that would help you make that prediction. So, here's my list. The biggest differences in life expectancy are based on geography. You remember earlier on how Professor Ezzati showed life expectancy varying by around 30 years between for example, Japan, with very long life expectancy and the Central African Republic, with much lower life expectancy. He also showed how deprivation has a major effect within a country, with variations of 8-10 years in life expectancy within the UK. After this lecture, you will have a chance to look at the videos by the late Hans Rosling on the relationship between health and wealth between and within countries. This is not just a macro-level difference between the high income and low income countries. Imperial college, where we're based now, is in Northwest London. You've probably seen pictures of the beautiful surroundings, wealthy buildings and extensive parks, but if you look more closely at the health and wealth of the local area, you see enormous contrasts. Our local area, Westminster, is home to 240,000 people. Overall, it's affluent with longer life expectancy than most of England. But within Westminster, there are huge differences. A baby born in the richest decile can expect to live nearly 90 years, while a baby born in the poorest will only live to about 77.5 years. A full 12.5 years less. Another major predictor of life expectancy is gender. Overall, women live four to six years longer than men. There are similar patterns of inequality for many health indicators. Take under five mortality, for example, where there's a 60 fold difference between Somalia and Iceland. These variations are called health inequalities and can be found between and within countries and between different groups of people. One major aim of epidemiology is to identify the causes of diseases. The specific etiology. In later courses, you can learn about recent research on the causes of heart disease, cancers and infections. Advances in biomedical technology, particularly in genomics, epigenetics, metabolomics and other omics, can identify very precise changes in genes and pathways that lead to disease. But we are also interested in factors that affect health more generally, and these are the determinants of health that underpin health inequalities I have described. They are sometimes called the causes of the causes of disease. Going back to the example of life expectancy, the factors that I suggested were place of birth wealth and gender. These are not biological, but more broadly social factors and part of what are called the social determinants of health. This term refers to the specific social condition such as income, education, access to resources and political representation that can vary between and within countries and are part of creating health inequalities. WHO definition of social determinants of health is: the conditions in which people are born, grow, live, work and age. These circumstances are shaped by the distribution of money, power and resources at global, national, and local levels. Frameworks can help us to visualize these. This first framework was developed by Goran Dahlgren and Margaret Whitehead in 1991 to show the determinants of health. Around the outside, you have some of the social determinants of health showing living and working conditions. As you work your way through the framework, you reach social and community networks, then individual lifestyle factors, such as smoking or physical activity, and the inner circle represents the determinants of the most basic tours are age, sex and physical constitutional factors. Sometimes it's possible to see quite direct relationships between different levels of this rainbow, as it's being called. For example, lung cancer is strongly associated with smoking, which is individual behavior. Although not all smokers get lung cancer. So, there are other factors involved. Smoking is influenced by social and community factors, with people being more likely to smoke if family and friends do. That in turn is influenced by education, living and working conditions, and finally by general social and economic conditions including: public policies on smoking and on taxation. This has been a brief introduction to the concept of social determinants of health. In the next lecture, I'll introduce you to the social gradient in health and look more deeply at how social factors affect health outcomes. Before I finish, I want to share an example of how influential social factors can be. In the late 1980s and 1990s, Russia underwent a major social, political and economic upheaval. This graph shows trends in age-standardized death rates, for men, for cancers, cardiovascular disease and external injury or poisoning. Death rates from cancer are fairly steady declining slightly, but deaths from the two other causes show a steep rise in the late 1980s and 1990s. This increased mortality has been attributed to an epidemic of alcohol misuse driven by the social turmoil and economic crisis as well as to changes in the recording of deaths and to the health system collapse. At that time, I was working in sexual health and HIV and I went to Moscow in 1995 on behalf of WHO Europe to investigate a big rise in cases of syphilis. That too had many complex drivers, but underpinning it all was the social and economic collapse, which led to the collapse of the health service and affected individual sexual behavior, migration, alcohol and drug use, and it led to an increase in poverty and sex work. These social factors created a perfect storm that allowed sexually transmitted infections to flourish and that example may help you understand why social determinants of health are so important to me and my work.
