What kills us?: Yesterday, today & tomorrow How much have mortality patterns changed and why? R.Fielding Synopsis: This lecture focuses on the changes in patterns of morbidity (ill-health) and mortality (death) from the middle of the 19th to the middle of the 20th Centuries, and how these changes have come about. The evidence that this lecture presents is well established, but not very popular, because it suggests that most of the benefits in terms of health gains, such as reduced morbidity and mortality have occurred as a result of changes in how people live their lives, rather than the technology of medical science. Drugs and technology have played a quite minor role in the improved life expectancy that has occurred. In contrast to this, most of the budget for health care is now spent not on the area that has been shown to be most important in determining health and well-being, but on the technological side of the health care industry, such as hospitals and attempts at curative approaches to the predominant degenerative diseases that we face today. Is this a good way to spend our money. Decide for yourself!

Learning objectives Define incidence, prevalence, morbidity and mortality Give examples of major ratios used to define morbidity and mortality Describe changes in cause of death in HK over the past century Give valid explanations for these changes There are a number of basic objectives to this lecture. These are, that by the end of this lecture, you should be able to define basic terminology of measures of morbidity and mortality, such as, incidence, prevalence, morbidity and mortality; give examples of mar ratios used to define morbidity & mortality; describe the major changes in the patterns of killing diseases in HK over the past 100 years; give valid explanations for the changes; describe the allocation of mortality to different categories of biology, environment, lifestyle, health care and contrast this with the expenditure in these areas; describe the major determinants of health at the community level.

Learning objectives Describe the allocation of mortality to different categories of biology, environment, lifestyle, health care and contrast this with the expenditure in these areas; Describe the major determinants of health at the community level

Definitions Morbidity: all ill-health, sickness, etc. Mortality: all deaths. Incidence: (number of new cases of a disease) / (popn. at risk) per unit time. Prevalence: all cases (new and old) of a disease/ total population per unit time. Ratio: proportion of those affected relative to a given unit of population or events Morbidity: a measure of all sickness or ill-health. Usually expressed as proportion (ratio) of a standard unit of the population (usually 10,000 or 100,000). Mortality: :ratio of the number of deaths to a given unit of population. Incidence: Number of new cases of a disease per unit of time Total population at risk Prevalence: Number of persons with a disease at a given point in time Total population Most of the measures of health and disease are expressed in the form of ratios. A ratio is a relative number expressing the magnitude of one occurrence in terms of another. Usually it is used in a specific sense where the numerator and denominator are two separate and distinct quantities. Neither is included in the other. A ratio does not depend on the size of the number, but on their relation to each other; i.e.,6 to 4, 75 to 50 and 10929 to 7286 may al be described by their ratio of 3:2 . Proportions are a type of ratio in which the numerator is included in the denominator, i.e. a/ (a+b). Some epidemiological expressions, which are in fact proportions, are loosely described as rates, e.g. proportion of fetal deaths= (number of fetal deaths /no. of conceptions) is usually referred to as the fetal death rate. It is in fact the proportion or relative frequency of fetal deaths among all conceptions and can be used as an estimate of the probability of this event.

Common ratios Mortality rate: Number of deaths per unit of population (10,000 or 100,000) Infant Mortality Rate: deaths among children < 1 year old total number of children < 1 year. Standardized Mortality Ratio (SMR): product of (number of observed deaths x100)/(number of expected deaths). >100 indicates excess deaths, < 100 indicates a lower mortality. Mortality rates are expressed in different ways: Generally or specifically. The overall mortality rate is the number of deaths in a given year over the total number in the population. However, as certain groups are more sensitive indicators of the health of a community than others, focussing on these particular groups gives us a better idea of the actual level of community health. The Neonatal MortalityRate (ratio) is the number of deaths in children < 1 month of age over the total number of children < 1 month. The Infant mortality Rate (ratio) is the same proportion but for children under one year of age. This is one of the best indicators of the level of health of a community. Standardization is often used to adjust for the changing structure of the population due to changing fertility, migration or war, in order that apparent changes in incidence, prevalence or mortality aren’t mistaken as actual changes in disease occurrence. Age-standardization is the most common form of standardization, with incidence, prevalence or mortality reported for given age bands, rather than the population as a whole. SMRs are used to compare mortality for different segments of the population, such as males vs. females, or people in different occupational groups vs. the workforce as a whole. If the SMR for a group exceeds 100, then that group have greater than expected mortality, and if less than 100 they have lower than expected mortality. Standardization is a general technique that can be used to adjust for the lack of homogeneity or consistency in the structure of the population.

Leading causes of death, HK. Take a look at the table above. This lists the top ten causes of death in Hong Kong for the years 1912, 1948, and 1993, being the earliest and most recent years respectively for which data were available at the time of writing, (source Department of Health Annual Report, HK Govt.). What can you notice about the changes that have occurred in the types of diseases responsible for the majority of deaths in the years reported? What types of diseases were important causes of deaths in 1912? Were these types of disease still important in 1948? What about 1993? How can you begin to account for these changes in the types of disease causing the greatest morbidity in the population of HK?

Expectation of life at birth, men, 1871-1971 (UK) This graph presents the average number of years of life that could be expected at birth for men living in the UK for the years 1871 through to 1961. The solid line are observed data, the dotted line represents a projection of the existing trend up to 1941 extrapolated to 1961. What do you notice about the trend? What reasons would you give to explain it? What happened around the time of the Second World War that might have lead to a flattening of the increase in expected years of life at birth? The graph appears to show that since 1871, life expectancy at birth has increased from about 41 years to about 67 years by 1970. If this represented actual gain in life expectancy, it would indicate tremendous health gain. But that is not the correct interpretation, although you will hear it said (often by people in the pharmaceutical and medical technology industries) that life expectancy has increased from 40 years to 70 years in the past 100 years thanks to modern medicine and drugs. Why is this graph misleading ? What is the correct interpretation?

Age-standardized annual mortality rates 1851-1930 (UK) 10,000 TB B, P, I 1,000 Whooping cough This chart shows age-standardized mortality rates (mortality rates adjusted for the differing proportions of people in different age groups in the population) from important infectious diseases (TB, tuberculosis; B,P,I, bronchitis, pneumonia and influenza) over the period 1851-1930. What does the graph show? ( Note: the scale is logarithmic.) The most obvious feature is the decline in mortality from these diseases over the period covered. To what can we attribute this decline? It is difficult to explain this decline by reference to medical technology for the simple reason that there was no medical technology for most of this time. Indeed, the causative agents for all of these conditions were unknown at the time the declines began: immunizations were not introduced until after the period covered by the chart; antibiotics did not exist and the ideas of antisepsis and hygiene emerged only in the 20th century. So what was responsible for these declines? A second important question is who did these diseases tend to kill? What effect would a decline in deaths among the most vulnerable groups have on expected years of life at birth? Measles 100 '51 '61 ''71 '81 '91 '01 '11 '21

Epidemiological model for disease evaluation This table outlines some interesting data. The first column on the left gives the proportion of deaths attributable to the six top causes of mortality in the USA in 1973, listed in the second column (Heart dis. =all heart disease; CVD, cerebro-vascular disease; pneumon = pneumonia; Respiratory= all other respiratory diseases). The third to sixth columns list the proportional contribution to the disease estimated to arise from each of the four columns of: 1. medical care (how much medical care does to prevent mortality from the particular diseases in column two), 2. lifestyle, 3. environmental and 4.biological contributions. These proportions are derived from epidemiological studies which What can you conclude about the predominant sources of cause or prevention of these conditions? If we look at the fourth most important cause of death in the Usa in 1973, accidents, we see that about 85% of the variance in accident rates arises from life style and environmental factors, with biology being largely irrelevant as a contributor (2%) and subsequent medical care accounting for little more than one sixth (13%) of the variation in mortality from accidents. Other causes, like cancer,have a larger estimated contribution from biology, but less from treatment.

Comparison of US Federal expenditure to allocation of mortality according to epidemiological model Compare this table with the previous one. This table details the expenditure in the USA in 1974-6 on the four different areas or components listed in the previous table (medical care, lifestyle, environment and biology). The right hand column lists the total estimated contribution to overall mortality from each of the four areas. The middle column gives the proportion of government expenditure allocated to each of these four areas in 1974-1976. While these data are getting a little dated now, they do indicate one thing quite clearly when you consider this table with the data in the previous table. Can you say what this is?

Questions 1. How has mortality changed in HK since 1900? 2. Why have these changes occurred? 3. What does this tell us about the important influences on mortality? 4. How should we be spending our health budget? The data presented so far in this lecture lead us to ask a number of questions: 1. In what ways has mortality changed in HK since 1900; 2. What has been responsible for these changes? 3. What can we deduce about the influences on mortality that are most significant? 4. Based on these data, how should we spend our health budget to maximize the gain for the limited expenditure available. The next few slides look at each of these questions in turn:

1. How has the pattern of mortality changed? From acute to chronic degenerative causes and (in children and younger adults) accidents. Life expectancy at adulthood little changed, but childhood survival improved during last 100 years. 1. In what ways has mortality changed in HK since 1900? From the chart of mortality in HK for 1912, 1948 and 1993 we can see that the change has been from acute, mainly infectious diseases, to chronic, degenerative conditions. The chart of life expectancy is misleading, because it represent the average number of years of life expectancy at birth. Averages are disproportionately affected by extreme scores. The apparent gains in years of life expectancy reflect a drop in deaths among children, mostly in the 0-5 years age group. The high proportions of deaths in these groups up to the early to mid 19th Centuries pulled the average years of expected life down quite sharply. Once childhood mortality began to fall, the average years of life expectancy increased, more closely reflecting the life expectancy of those who managed to survive the vulnerable years of childhood. In fact, the life expectancy for a male aged 40 has increased only by about 3-5 years over the past 100 years. Smaller families, and from the post-WWI years onwards gradual improvements in maternal care, has reduced maternal-related mortality , the major cause of premature death among women in the UK up to and during the 19th Century.

How has mortality changed? (cont.) Infectious disease mortality declined before causes (and Rx) were identified, so medical interventions not responsible what else happened in Europe 1830-1930 and HK 50 years later? However, to reiterate and anticipate the second question, what were the reasons for the decline in childhood mortality from infectious diseases? As the decline began before most causes were identified, medical interventions cannot account for the changes. What else was happening in Europe between 1830-1930 and in HK from after WWII? The most notable development was the industrial revolution. This, together with sweeping changes in the laws governing land use, was preceded by and amplified a mass movement of people from the previously dominant agricultural sector to urban environements, often in search of work and higher wages in the emerging factories. This urban drift lead to considerable strain on the capacity of cities to cope with the food, sanitation and other resources. Poor housing, over-crowding and poor nutrition lead to an increase in infectious disease amongst the most vulnerable, the young, the very old, the poorly nourished and otherwise weakened. From around 1850 onwards growing attempts to introduce significant infrastructural and legislative means to help cope with the high levels of disease, crowned by the introduction of the Public Health Act in 1897 ensured standards for housing, sanitation, drinking water, food quality that were previously lacking. The gradual appearance of contraception and the increased childhood survival lead to smaller families, placing less reproductive strain on women, enabling better nourishment for children, compulsory education and improved wealth from industrial and colonial activities all contributed.

2. What has contributed to these changes? (a) Changes in the nature of work Food hygiene laws, improved income => better nutrition Infrastructure development => better living conditions clean drinking water sewage disposal Changes in the nature of work from hard physical labour to more sedentary types of work has lead to changes in activity levels. This, together with greater access to increased amounts of foods has lead to an increase, not in under-nutrition (in the post-industrial nations), but over-nutrition. Diseases of over-nutrition and inactivity, principally hypertension and diabetes, are becoming among the most important health problems we will face and are set to become even more important. This has been exacerbated by increased reliance on motorized transport. In parts of the world where these infrastructural developments have not happened, high levels of infant mortality persist. Providing education to girls and easy access to clean drinking water are the most effective ways to bring down infant mortality.

2. What has contributed to these changes?(a) Decline in fertility rate altered family size, birth spacing and age distribution; => increase in median age of infection and lower case fatality rate; => More children survived, so the mean age of the population increased. Fertility changes have an important role to play. Closely spaced births both weaken the mother, who has insufficient time to recover from the demands of the previous pregnancy before she is once again pregnant, and mean that children are weaned by the arrival of new baby earlier than they should be, placing them at greater risk of GI diseases such as diarrhoea, and subsequent nutritional weakening. The family age distribution is greater. The median age of infection for common childhood infections is consequently higher, by which time the child is stronger and more able to resist the infection. More children survive the infectionsso the mean age of the population increases, which gives the appearance of an increase in life life-expectancy.

Expectation of life at birth, men, 1871-1971 (UK) So, by re-visiting this graph, we can see that the deviation from the projected line which begins around 1941 may be interpreted as reflecting several things. First, by this time, few children were dying so there was little gain in the average years of life expectancy. Second, the higher mortality among young males during WWII would have pulled this average down. If this were a significant contributor, we will expect to see the line of life expectancy begin to increase its slope again after 10 or 20 more years. Third, at around the time of WWII, new medical technologies,spurred on by the war were beginning to emerge. In the 1950s these may have begun to slow down the improvements in years of life expectancy. Changes in society (inactivity, under-nutrition followed by over-nutrition) may have begun to have a negative impact on average years of life expectancy. Another change may have been shrinking family sizes and fewer children available to die in childhood up to the war years, followed by the baby boom in the optimistic post-war period may have increased numbers of vulnerable children. Can you think of other interpretations or explanations for the chart pattern?

2. What has contributed to these changes?(b) From W.W.II onwards change in activity levels: less manual labour more motorized transport. Increases in disposable income food availability & marketing strategies dietary and other substance intake We have considered many of the influences already, but the slide shows some more. One important factor shown recently to be important in determining health for as far back as the 14th Century to the present day is relative wealth. Even in countries with high per capita income the most wealth have better health overall than those somewhat less wealth but still materially very comfortable. In poor societies, the slightly better off have better health than the slightly worse off. This wealth related relative health effect has been shown in terms of the positive correlation between the sizes of dowries given by Florentine people in the 14th Century upon marriages of their daughters and the daughter’s subsequent age of death; between the size of tombstones in 19th Century Scottish churchyards (a proxy measure of wealth) and the age at death inscribed upon the tombstones, and the rapid and substantial decline in life-expectancy by about 5-6 years among Russian males since the collapse of Communism, and particularly since the economic collapse of Russia. These data are compelling evidence that relative material status, not just absolute levels of wealth, has important impact on life expectancy.

2. What has contributed to these changes?(b) Increase in body mass (DM, CHD, HT) Tobacco / alcohol use / environmental degradation > rise in chronic disease prevalence. Economic developments, loss of control, competitiveness. Inactivity and greater access to nutrition leads to increase body mass. This is made worse by communities which have adapted genetically to low calorific diets suddenly (in evolutionary terms) having unlimited access to calorie-dense diets. Other profit driven products (including processed, “value-added” - read more expensive- foods; tobacco and alcohol) are marketed aggressively, and environmental degradation from unrestrained population pressure on limited resources are contributing to rising disease prevalence. Economic growth, driving increased competitiveness, greater pressure on the workforce, less control over work, chronic unemployment and more work insecurity contribute to significant adaptive demand on people, leading to more extreme forms of “relaxation” such as substance abuse, and breakdown of traditional support systems such as the family and community. The nutritional environment prevailing in the uterine environment during gestation seems to “set” the body’s metabolic tone. Variation throughout the life-span from this nutritional standard is associated with greater risk of a range of chronic diseases, including CHD, diabetes and other currently-important chronic diseases. This is called “Barker’s Hypothesis”. So mothers who had lo, but adequate, nourishment during their pregnancies, and who give birth to low weight babies, which are then subject to a richer nutritional environment, showing increased weight gain and higher BMI as children and adults are at greater risk of many diseases, than either low birth weight babies that retain low BMI throughout life, or high b.w. babies that retain high b.w.

3. What does this tell us about important influences on mortality? Improvements in life expectancy small despite massive expenditure on health care delivery. Most mortality declines due to economic, cultural, behavioral and domestic changes Societal, cultural and behavioural influences have been more important that medical care. Well, what can we conclude from the data you have seen so far? 1. Despite the massive expenditure of health services delivery since WWII, the improvements in life expectancy have been meagre and far short of what might be expected from the trillions of US$ spent. 2. Most of the declines in mortality from the mid 19th to the mid 20th Centuries were due to societal, cultural, behavioural, educational and domestic changes, many of which were driven by legislation. 3. Changes in the way people live their lives prove to be far more effective in changing mortality rates than does better and more expensive medical technology. Sometimes these changes can be as simple as providing education for girls, changing food preparation or making condoms available for family planning.

4. How should we be spending our health budget to improve health further? Many current causes of mortality incurable. Prevention best approach to further reductions in mortality Economic and occupational improvements are among most important developments. Environmental degradation (consumer behaviour) is now most important threat. What does all this suggest for the way we should be spending our money on health? In HK, 90% of the money allocated to health care is spent by the hospital authority, and only 10% goes to the Department of Health. There are other areas that receive funding not explicitly under the health care budget, which make an important contribution to health, such as education, social services, urban services, such as sanitation and infra-structural maintenance including water and sewerage. When we look at the current dominant causes of mortality, they are all mostly incurable (which is one reason why they are the dominant causes of mortality). This means that prevention is the more effective approach to reduce the prevalence of these diseases. Economic, educational and occupational improvements are very important in improving health, but past a certain point, they can begin contributing to the problem they are trying to erase. Unrestrained population growth coupled with rampant consumerism now poses the greatest threat to health trends. Increased pollution, growing competition for scare resources, including water and land, excessive environmental contamination by man-made chemicals such as hormone analogues, destabilization, migration and war are the most important health threats that need to be tackled.

Mortality from coronary heart disease, men (20-64) UK This chart depicts age-standardized mortality for CHD arranged by the Registrar General of the UK’s occupational groupings in the UK. What can you deduce from the chart? What explanations do you have for the gradations in mortality?

phenotype genotype phenotype genotype behaviour behaviour environment Mortality is not a simple case of dying. It is a complex end product of interactions between phenotype and environment, which is modulated by the behaviour of the individual, the group and the population. The most amenable area for intervention is both the environment and behaviour. But remember. Once you remove the present causes of mortality. New (or old) causes will emerge (or re-emerge) to continue being cited as the “cause” of death. One thing is certain, we will all die, of something. The crucial point seems to be ho to achieve as long and disease and disability-free life as is feasible, with as short a decline and death at the end of life as possible for as many people as possible. Death has no cure. environment

Conclusions Economic/political, social & individual behaviour impacts on environment and behaviour, disturbing systemic homeostasis (ecosystem), result is increased risk exposure and heightened vulnerability. Economic, political, social and behavioural dimensions impact on the ecosystems we call environment, placing hemoestatic demand upon people. This results in increased risk exposure, declining adaptability with increasing age and exposure and heightened vulnerability with increasing deprivation.

Conclusions Mortality primarily influenced by socio-economic factors through opportunity and personal behaviour. Future declines in mortality will derive mostly from social-level changes (e.g. legislation on drink-driving, smoking, pollution, education) and personal behaviour. Preventive measures offer better value for money. Socio-economic factors are the primary influences on mortality in all communities at all times. These seem to impact by the effect they have on the range of behaviour people exhibit. Future mortality declines will be most likely to occur following societal level changes, often legislative, in such areas as tobacco control, traffic legislation, and specific personal behavious, such as smoking. Prevention is always better than cure. And better value for money too!