Introduction

The first World Bank Global Burden of Disease Study [5] was set up to assess the burden of disease consistently across regions, diseases and risk factors and to develop methods to estimate health loss associated with deaths and disability, measuring the number of years of full health lost. The study introduced the concept of the disability-adjusted life year (DALY) (see Figure 1). This allows the years of life lost due to premature death (for example, pneumonia in children) to be quantified along with chronic, disabling diseases that do not cause death (for example, cataracts causing blindness) but reduce the years of life lived in full health. The study describes the burden of disease itself as “a measurement of the gap between the current health status and the ‘ideal’ situation – where everyone lives into old age, free of disease and disability” [5].

Figure 1

Percentage of disability-adjusted life years (DALYs) attributed to 19 leading risk factors, by country income level, 2004 [6]

GBD Estimates in Scotland and the UK

The Scottish Public Health Observatory compared mortality between Scotland and other countries for 1950-2000 in 2006 [7]. A preliminary estimate of UK burden of disease was carried out in 2008 [8].

Reducing the Global Burden of Disease contributes to “the ‘ideal’ situation – where everyone lives into old age, free of disease and disability.”

The World Health Organization (WHO) supports regular updates on the number of cases, disability and deaths for over one hundred diseases and injuries. These estimates now include the most important risks underlying the major diseases. They also identify the risk factors to be tackled if the global burden of disease is to be reduced successfully. Estimates of the burden of disease provide valuable data for planning approaches to prevention and health services and for informing priority setting and resource allocation. This report examines the conditions that impact most on the global burden of disease and illustrates the common nature of the risk factors. Exposure to these risks, however, is shaped by the social, environmental and economic factors that are the wider social determinants of health and effective action, whether at global or local level, requires attention to risk and the reasons why we are exposed in the first place.

The Global Situation

In 2004, about 59 million people died across the world. The number one killer was cardiovascular diseases. In 2004, 7.2 million people (12.2%) died of coronary heart disease and 5.7 million (9.7%) from stroke or another form of cerebrovascular disease. To put this into context, imagine a diverse international group of 1,000 individuals, representative of the people who died in 2004. Of those 1,000, 138 would have come from high-income countries, 415 from middle-income countries and 447 from low-income countries. Figure 2 shows the main causes of deaths in high, middle and low income countries of the world.

Figure 2

Top 10 causes of death by country income levels [9]

In high-income countries, more than two-thirds of all people live beyond the age of seventy and predominantly die of chronic diseases: cardiovascular disease, chronic lung disease, cancers, diabetes or dementia. Pneumonia is the only leading infectious cause of death. In middle-income countries, nearly half of all people live to the age of seventy and chronic diseases are the major causes of death, just as they are in high-income countries. Unlike in highincome countries, however, tuberculosis and road traffic accidents are also leading causes of death. In low-income countries fewer than a quarter of all people reach the age of seventy and over a third of all deaths are among children under fourteen. People predominantly die of infectious diseases: pneumonia, diarrhoeal diseases, HIV/AIDS, tuberculosis and malaria. Complications of pregnancy and childbirth continue to be leading causes of death claiming the lives of neonates and mothers.

Low and middle-income countries now face a double burden of increasing chronic, non-communicable conditions and communicable diseases that traditionally affect resource-poor countries. Over ten million deaths in 2004 were among children under five years of age and 99% of them were in low and middle-income countries. The main causes are neonatal problems, pneumonia, diarrhoeal disease and malaria. An estimated 39% of child deaths (4.1 million) were caused by micronutrient deficiencies (lack of essential vitamins and minerals), underweight, suboptimal breastfeeding and preventable environmental risks. Most of these preventable deaths occurred in the WHO African Region (39%) and the South- East Asia Region (43%) [5].

The leading global risks for mortality are high blood pressure (responsible for 13% of deaths globally), tobacco use (9%), high blood glucose (6%), physical inactivity (6%), and overweight and obesity (5%). These factors are responsible for increasing the risk of chronic diseases such as heart disease, diabetes and cancers. They affect countries across all income groups: high, middle and low.

Eight factors that increase risk of death from cardiovascular disease are: alcohol use, tobacco use, high blood pressure, high body mass index, high cholesterol, high blood glucose, low fruit and vegetable intake and physical inactivity. 61% of cardiovascular deaths, the leading cause of death worldwide, can be attributed to these risks. Although these risk factors are usually associated with high-income countries, over 84% of the total global burden of disease that they cause occurs in low and middle-income countries. Reducing exposure to these eight risk factors would increase global life expectancy by almost five years.

Nine environmental and behavioural risks, together with seven infectious causes, are responsible for 45% of cancer deaths worldwide. For specific cancers, the proportion is higher: for example, tobacco smoking alone causes 71% of lung cancer deaths worldwide. Tobacco accounted for 18% of deaths in high-income countries and almost one in ten adults worldwide.

Patterns of disease are changing across the world due as a consequence of changing socio-economic circumstances, the decline in communicable diseases and an ageing population. The most recently published estimates of global mortality and burden of disease suggest that the proportion of deaths due to non-communicable disease (mainly cardiovascular disease and cancer) will rise from 59% to 69% between 2002 and 2030 [7]. By 2015, the number of deaths associated with tobacco use each year is expected to exceed the number of deaths from HIV/AIDS by 50% and to be associated with 10% of all deaths. If approaches to prevention remain unchanged the four leading causes of burden of disease in 2030 are likely to include HIV/AIDS, unipolar depressive disorders, coronary heart disease and road traffic accidents.

The Scottish situation

In 2009, 53,856 deaths were registered in Scotland [10]. This was the lowest total recorded since the introduction of civil registration in 1855 but more than half of all deaths were still due to the so-called ‘three big killers’ (see Figure 3).

Figure 3

Causes of death in Scotland [10]

The ‘top ten causes of death’ in Scotland are broadly similar to the main causes of death in other high income countries (see Figure 1).

Other common causes of deaths registered in 2009 are included in Table 1.

Table 1

Other common causes of death in Scotland, 2009 [10]

There were 235 deaths of infants (children aged under 1) in 2009; a rate of 4 deaths per 1000 live births [11]. In 2005, the infant mortality rate was 5.2 per 1000 in Scotland compared with 2.4 per 1000 in Sweden [12].

Figure 4

Estimated numbers of people with diabetes based on populations alone or combination with trends in BMI [14]

Case study:

fUtUrE DiaBEtEs in scotLanD

Burden of disease estimates for diabetes in Scotland are based on populationbased data on diabetes diagnoses combined with survey estimates of the proportion of diabetes that is undiagnosed [8]. Future projections have been made based on trends in the main factors that influence diabetes risk in a population: the distribution of age, sex and body mass index. Figure 4 shows the steep increase in cases of diabetes that can be expected over the next twenty years and for which prevention and early attention are required urgently. These estimates can also be used to:

  1. Estimate the impact of introducing a systematic diabetes prevention programme including diet, exercise and practice [13].
  2. Predict the effects of a screening programme to identify people with undiagnosed diabetes and of interventions that reduce the prevalence of obesity in the Scottish population, similar to approaches used in other countries to predict the future burden of diabetes.
  3. Estimate the future need for more screening for the eye complications of diabetes.

“A steep increase in cases of diabetes ... can be expected over the next twenty years ... prevention and early attention are required.”

Key points

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