Burden of Disability and Poor Health in 2001
As defined earlier, YLD measure the equivalent years of healthy life lost through time spent in states of less than full health. The original GBD study brought the previously largely ignored burden of nonfatal illnesses, particularly mental disorders, to the attention of health policy makers. The findings of the GBD 2001, based on updated data and analyses, confirm that disability and states of less than full health caused by diseases and injuries play an important role in determining the overall health status of populations in all regions of the world.
Leading Causes of YLD in 2001
Tables 3.12 and 3.13 show the 10 leading causes of YLD(3,0) by broad income group and by sex. A relatively short list of causes dominates the overall burden of nonfatal disabling conditions. In both income regions, neuropsychiatric conditions are the most important causes of disability, accounting for more than 37 percent of YLDs(3,0) among adults ages 15 and over. The disabling burden of neuropsychiatric conditions is almost the same for males and females, but the major contributing causes are different. While depression is the leading cause for both males and females, the burden of depression is 50 percent higher for females than for males, and females also have a higher burden from anxiety disorders, migraine, and senile dementias. In contrast, the male burden for alcohol and drug use disorders is nearly six times higher than that for females and accounts for one-quarter of the male neuropsychiatric burden.
[Table .]
[Table .]
Globally, cataracts and age-related vision disorders together account for more than 9 percent of total YLD(3,0), and adult-onset hearing loss accounts for another 5.2 percent. Adult-onset hearing loss is extremely prevalent, with more than 27 percent of men and 24 percent of women aged 45 and over experiencing mild hearing loss or greater. The GBD 2001 has estimated only the burden of moderate or greater hearing loss. Childhood-onset hearing loss is not included in this cause category, as most childhood hearing loss is due to congenital causes, infectious diseases, or other diseases or injuries, and is included as sequelae for such causes in the estimation of the burden of disease.
In both low- and middle-income countries and high-income countries, alcohol use disorders are among the 10 leading causes of YLD(3,0). This includes only the direct burden of alcohol dependence and problem use. The total attributable burden of disability due to alcohol use is much larger (see chapter 4 ).
More than 80 percent of global nonfatal health outcomes occur in developing countries, and high-mortality developing countries account for nearly half of all YLD. Although the prevalences of disabling conditions such as dementia and musculoskeletal disease are higher in countries with long life expectancies, this is offset by lower contributions to disability from conditions such as CVD, chronic respiratory diseases, and long-term sequelae of communicable diseases and nutritional deficiencies. In other words, people living in developing countries not only face shorter life expectancies than those in developed countries, but also live a larger proportion of their lives in poor health.
Regional Variations in Healthy Life Expectancy
In the original GBD study, Murray and Lopez (1996c) computed a form of health expectancy referred to as disability-adjusted life expectancy using age- and sex-specific YLD rates and regional life tables to compute the expected equivalent years of healthy life in each region. Their results clearly demonstrated that populations with higher mortality also had higher prevalences of disability and lower health expectancies.
WHO has used a similar indicator, referred to as healthy life expectancy (HALE), to report on the average levels of population health for its 192 member countries (
WHO 2004b
). We calculated HALE at birth for regions in 2001 (
figure 3.10
) using the GBD 2001 estimates for YLD by region, age, and sex, together with information on health state prevalences and valuations from the WHO Multicountry Survey Study on Health and Responsiveness carried out in 2000 and 2001 (
Ustun, Chatterji, Villanueva, and others 2003
). For a description of the methods used to calculate HALE see
Mathers, Salomon, and others (2003)
. Regional variations in HALE have also been discussed in more detail elsewhere, as have estimates of regional variations in increases in HALE associated with the elimination of selected health risks (
Ezzati and others 2003
;
Mathers, Murray, and others 2003
).
[Figure
3.10]
Overall, global HALE at birth in 2001 for males and females combined was 57.4 years, 7.5 years lower than total life expectancy at birth ( figure 3.10 ). In other words, on average, poor health resulted in a loss of nearly eight years of healthy life globally. Global HALE at birth for females was only 2.7 years greater than that for males. In comparison, female life expectancy at birth was 4.2 years higher than that for males. Global HALE at age 60 was 12.7 years and 14.7 years for males and females, respectively, 4.3 years lower than total life expectancy at age 60 for males and 5.3 years lower for females.
HALE at birth ranged from a low of 40 years for males in Sub-Saharan Africa to more than 70 years for females in high-income countries. This reflects an almost twofold difference in HALE between major regional populations ( figure 3.10 ). The equivalent "lost" healthy years (total life expectancy minus HALE) ranged from 15 percent of total life expectancy at birth in Sub-Saharan Africa to 8 percent in high-income countries. The sex gap was highest for Europe and Central Asia and lowest in the Middle East and North Africa.
