Measuring the global burden of disease and epidemiological transitions: 2002-2030.

Any planning process for health development ought to be based on a thorough understanding of the health needs of the population. This should be sufficiently comprehensive to include the causes of premature death and of disability, as well as the major risk factors that underlie disease and injury. To be truly useful to inform health-policy debates, such an assessment is needed across a large number of diseases, injuries and risk factors, in order to guide prioritization. The results of the original Global Burden of Disease Study and, particularly, those of its 2000-2002 update provide a conceptual and methodological framework to quantify and compare the health of populations using a summary measure of both mortality and disability: the disability-adjusted life-year (DALY). Globally, it appears that about 56 million deaths occur each year, 10.5 million (almost all in poor countries) in children. Of the child deaths, about one-fifth result from perinatal causes such as birth asphyxia and birth trauma, and only slightly less from lower respiratory infections. Annually, diarrhoeal diseases kill over 1.5 million children, and malaria, measles and HIV/AIDS each claim between 500,000 and 800,000 children. HIV/AIDS is the fourth leading cause of death world-wide (2.9 million deaths) and the leading cause in Africa. The top three causes of death globally are ischaemic heart disease (7.2 million deaths), stroke (5.5 million) and lower respiratory diseases (3.9 million). Chronic obstructive lung diseases (COPD) cause almost as many deaths as HIV/AIDS (2.7 million). The leading causes of DALY, on the other hand, include causes that are common at young ages [perinatal conditions (7.1% of global DALY), lower respiratory infections (6.7%), and diarrhoeal diseases (4.7%)] as well as depression (4.1%). Ischaemic heart disease and stroke rank sixth and seventh, retrospectively, as causes of global disease burden, followed by road traffic accidents, malaria and tuberculosis. Projections to 2030 indicate that, although these major vascular diseases will remain leading causes of global disease burden, with HIV/AIDS the leading cause, diarrhoeal diseases and lower respiratory infections will be outranked by COPD, in part reflecting the projected increases in death and disability from tobacco use.

The burden of disease and injury in Australia.

An overview of the results of the Australian Burden of Disease (ABD) study is presented. The ABD study was the first to use methodology developed for the Global Burden of Disease study to measure the burden of disease and injury in a developed country. In 1996, mental disorders were the main causes of disability burden, responsible for nearly 30% of total years of life lost to disability (YLD), with depression accounting for 8% of the total YLD. Ischaemic heart disease and stroke were the main contributors to the disease burden disability-adjusted life years (DALYs), together causing nearly 18% of the total disease burden. Risk factors such as smoking, alcohol consumption, physical inactivity, hypertension, high blood cholesterol, obesity and inadequate fruit and vegetable consumption were responsible for much of the overall disease burden in Australia. The lessons learnt from the ABD study are discussed, together with methodological issues that require further attention.

Healthy life expectancy in 191 countries, 1999.

We describe here the methods used to produce the first estimates of healthy life expectancy (DALE) for 191 countries in 1999. These were based on estimates of the incidence, prevalence, and disability distributions for 109 disease and injury causes by age group, sex, and region of the world, and an analysis of 60 representative health surveys across the world. We used Sullivan's method to compute healthy life expectancy for men and women in each WHO member country. Japan had the highest average healthy life expectancy of 74.5 years at birth in 1999. The bottom ten countries are all in sub-Saharan Africa, where the HIV-AIDS epidemic is most prevalent, resulting in DALE at birth of less than 35 years. Years of healthy life lost due to disability represent 18% of total life expectancy in the bottom countries, and decreases to around 8% in the countries with the highest healthy life expectancies. Globally, the male-female gap is lower for DALE than for total life expectancy. Healthy life expectancy increases across countries at a faster rate than total life expectancy, suggesting that reductions in mortality are accompanied by reductions in disability. Although women live longer, they spend a greater amount of time with disability. As average levels of health expenditure per capita increase, healthy life expectancy increases at a greater rate than total life expectancy.

The burden of mental disorders: a comparison of methods between the Australian burden of disease studies and the Global Burden of Disease study.

The national and Victorian burden of disease studies in Australia set out to examine critically the methods used in the Global Burden of Disease study to estimate the burden of mental disorders. The main differences include the use of a different set of disability weights allowing estimates in greater detail by level of severity, adjustments for comorbidity between mental disorders, a greater number of mental disorders measured, and modelling of substance use disorders, anxiety disorders and bipolar disorder as chronic conditions. Uniform age-weighting in the Australian studies produces considerably lower estimates of the burden due to mental disorders in comparison with age-weighted disability-adjusted life years. A lack of follow-up data on people with mental disorders who are identified in cross-sectional surveys poses the greatest challenge in determining the burden of mental disorders more accurately.

The Australian Burden of Disease Study: measuring the loss of health from diseases, injuries and risk factors.

This is an overview of the first burden of disease and injury studies carried out in Australia. Methods developed for the World Bank and World Health Organization Global Burden of Disease Study were adapted and applied to Australian population health data. Depression was found to be the top-ranking cause of non-fatal disease burden in Australia, causing 8% of the total years lost due to disability in 1996. Mental disorders overall were responsible for nearly 30% of the non-fatal disease burden. The leading causes of total disease burden (disability-adjusted life years [DALYs]) were ischaemic heart disease and stroke, together causing nearly 18% of the total disease burden. Depression was the fourth leading cause of disease burden, accounting for 3.7% of the total burden. Of the 10 major risk factors to which the disease burden can be attributed, tobacco smoking causes an estimated 10% of the total disease burden in Australia, followed by physical inactivity (7%).

Socioeconomic status and health in Australia.

Consistent with international evidence, the findings of Australian research show that socioeconomically disadvantaged groups experience significantly higher mortality and morbidity rates. Despite marked improvements in the health of all segments of the Australian population in recent decades, during this same period there has also been an increase in socioeconomically related mortality inequalities for some conditions. Socioeconomically disadvantaged groups are more likely to engage in health-damaging behaviours, experience poorer psychosocial health, make less use of the healthcare system for preventive purposes, and have a more adverse risk factor profile. These are the main contributing factors to the poorer physiological health of low socioeconomic groups. At present, our knowledge of how socioeconomic status and health are related is limited. A necessary step in improving our understanding of this issue is to draw together all the empirical evidence and use it as the basis for developing a theory of socioeconomic health inequalities. We present a conceptual framework to facilitate this process.

Gains in health expectancy from the elimination of diseases among older people.

PURPOSE: This paper examines a health expectancy based approach to obtaining disease-specific measures of the contribution of health problems to loss of healthy life among older people. Health expectancies combine mortality and morbidity into a single population health measure. The objectives of this study are to evaluate the usefulness of potential gains in health expectancies as a measure of health impact of various chronic diseases and injury among older people and to examine whether elimination of specific diseases and injuries leads to a compression or expansion of morbidity. Results are presented for Australians aged 65 years and over in 1993. RESULTS: The results highlight the importance of the chronic non-fatal diseases such as osteoarthritis and eyesight and hearing problems as causes of disability and handicap in older people. Elimination of such diseases results in an increase in healthy years of life while total life expectancy remains unchanged, leading to an absolute compression of morbidity. At the other extreme, elimination of highly fatal diseases such as cancer can result not only in an increase in healthy years but an even larger increase in years with disability, resulting in a relative expansion of morbidity.

The health consequences of unemployment: the evidence.

Mathers and Schofield, from the Australian Institute of Health and Welfare, review recent studies, including Australian research, on the health effects of unemployment and the mechanisms by which unemployment causes adverse health outcomes. The relationship is complex: ill-health also causes unemployment, and confounding factors include socioeconomic status and lifestyle. However, longitudinal studies with a range of designs provide reasonably good evidence that unemployment itself is detrimental to health and has an impact on health outcomes--increasing mortality rates, causing physical and mental ill-health and greater use of health services.

How good is Sullivan's method for monitoring changes in population health expectancies?

STUDY OBJECTIVE: To compare health expectancies calculated by Sullivan's method and the multistate life table method in order to identify the magnitude of the bias in Sullivan's method and assess how seriously this limits its use for monitoring population health expectancies. DESIGN: A simulation model was used to compare health expectancies calculated using Sullivan's method and the multistate life table method under various scenarios for the evolution of disability over time in populations. The simulation model was based on abridged cohort life tables using data on French mortality from 1825-90 and disability prevalence data from the 1982 French health survey. MAIN RESULTS: The Sullivan method could not detect a sudden change in disability transition rates, but the simulations suggested that it provides a good estimate of the true multistate value if there are smooth and relatively regular changes in disability prevalence over the longer term. When disability incidence rates are increasing or decreasing smoothly over time, the absolute bias in the Sullivan estimate of disability free life expectancy is relatively constant with age. The relative bias thus increases at older ages as disability free life expectancy decreases. CONCLUSIONS: The difference between the estimates produced by the two methods was small for realistic scenarios for the evolution of population health and Sullivan's method is thus generally acceptable for monitoring relatively smooth long term trends in health expectancies for populations.

Utilisation of acute hospitals by age and sex in Australia, 1985.

This paper provides estimates of the utilisation rates of acute care (short-stay) hospitals, by age and sex, for the Australian population. Separation and bed-day rates per 1000 persons for public, Repatriation and private hospitals in 1985 have been estimated by age group, for each sex, in each State and Territory in Australia. The Australian Base Grant, negotiated between the Commonwealth, States and Territories in the new Medicare Agreements, distributes funds for the care and treatment of Medicare patients in public hospitals. The national bed-day utilisation rates reported in this article, have been used as the basis for population weights to allocate these funds. This paper presents the data and methods used to derive these weights, and examines the differences between them and the actual State and Territory utilisation patterns in 1985. The impact of population ageing on the overall utilisation rates for acute hospitals in Australia is examined.

A study of caffeine consumption and symptoms; indigestion, palpitations, tremor, headache and insomnia.

In a cross-sectional study of 4558 Australians, it was found that the proportion of subjects reporting indigestion, palpitations, tremor, headache and insomnia increased significantly with mean caffeine intake. A multiple logistic regression model was used to show that the association between the prevalence of these symptoms and usual daily caffeine consumption remained significant in both males and females for palpitations, tremor, headache and insomnia after controlling for the potential confounding factors of age, adiposity, smoking, alcohol intake and occupation. Adiposity was strongly correlated with the prevalence of indigestion and the apparent association between caffeine and indigestion disappeared when adiposity was controlled for. According to the logistic model, the relative risk of experiencing symptoms for people consuming 240 mg of caffeine (approximately 4-5 cups of coffee or tea) per day (the population average) compared with caffeine abstainers is 1.6 for palpitations, 1.3 for tremor, 1.3 for headache, and 1.4 for insomnia in males and 1.7, 1.5, 1.2 and 1.4 respectively for females. Further logistic regression analysis indicated that the associations found between caffeine intake and symptoms did not depend on the source of caffeine. In general, coffee consumption has no significant effect over and above that attributable to its caffeine content. If these associations are causal, then approximately one quarter of the reported prevalence of palpitations, tremor, headache and insomnia is attributable to caffeine consumption in this study population.

Caffeine consumption and serum cholesterol levels.

Caffeine consumption was significantly associated with serum cholesterol levels in women but not in men in a cross-sectional study of 4757 Australians. Use of caffeinated coffee by men, but not total caffeine consumption rate, was significantly associated with raised serum cholesterol. Potential confounding factors including age, adiposity and occupation were controlled for in this analysis. After adjusting for age and adiposity, the mean serum cholesterol level was 11 mg/dl higher for women consuming 200 mg or more of caffeine per day compared with those consuming less. The relative risk of high serum cholesterol (greater than 260 mg/dl) was greater than 2 for women consuming 200 mg or more of caffeine per day. A significant positive interaction between smoking and caffeine consumption in their association with serum cholesterol levels was found for females.

Seasonal distribution of births in Australia.

Seasonal variations of births in Australia from 1911 to 1940 and 1962 to 1979 are analysed using stepwise periodic regression analysis. It is shown that the seasonality pattern has changed significantly from a September peak in the early 1960s to a February-March peak in the late 1970s. There also appears to be a significant geographical trend in seasonality of births with a February-March peak in the more northern States of Australia giving way to a September-October peak in the southernmost States. The seasonality of Australian births in 1976 to 1979 is shown to be independent of legitimacy and birth order but dependent on maternal age. The evidence suggests that environmental factors play a more important role than sociocultural factors in the causation of seasonal variations in births.