Disease burden

Disease burden is the impact of a health problem as measured by financial cost, mortality, morbidity, or other indicators. It is often quantified in terms of quality-adjusted life years (QALYs) or disability-adjusted life years (DALYs), both of which quantify the number of years lost due to disease (YLDs). One DALY can be thought of as one year of healthy life lost, and the overall disease burden can be thought of as a measure of the gap between current health status and the ideal health status (where the individual lives to old age free from disease and disability). According to an article published in The Lancet in June 2015, low back pain and major depressive disorder were among the top ten causes of YLDs and were the cause of more health loss than diabetes, chronic obstructive pulmonary disease, and asthma combined. The study based on data from 188 countries, considered to be the largest and most detailed analysis to quantify levels, patterns, and trends in ill health and disability, concluded that 'the proportion of disability-adjusted life years due to YLDs increased globally from 21.1% in 1990 to 31.2% in 2013.' The environmental burden of disease is defined as the number of DALYs that can be attributed to environmental factors. These measures allow for comparison of disease burdens, and have also been used to forecast the possible impacts of health interventions. By 2014 DALYs per head were '40% higher in low-income and middle-income regions.' Disease burden is the impact of a health problem as measured by financial cost, mortality, morbidity, or other indicators. It is often quantified in terms of quality-adjusted life years (QALYs) or disability-adjusted life years (DALYs), both of which quantify the number of years lost due to disease (YLDs). One DALY can be thought of as one year of healthy life lost, and the overall disease burden can be thought of as a measure of the gap between current health status and the ideal health status (where the individual lives to old age free from disease and disability). According to an article published in The Lancet in June 2015, low back pain and major depressive disorder were among the top ten causes of YLDs and were the cause of more health loss than diabetes, chronic obstructive pulmonary disease, and asthma combined. The study based on data from 188 countries, considered to be the largest and most detailed analysis to quantify levels, patterns, and trends in ill health and disability, concluded that 'the proportion of disability-adjusted life years due to YLDs increased globally from 21.1% in 1990 to 31.2% in 2013.' The environmental burden of disease is defined as the number of DALYs that can be attributed to environmental factors. These measures allow for comparison of disease burdens, and have also been used to forecast the possible impacts of health interventions. By 2014 DALYs per head were '40% higher in low-income and middle-income regions.' The World Health Organization (WHO) has provided a set of detailed guidelines for measuring disease burden at the local or national level. In 2004, the health issue leading to the highest YLD for both men and women was unipolar depression; in 2010, it was lower back pain. According to an article in The Lancet published in November 2014, disorders in those aged 60 years and older represent '23% of the total global burden of disease' and leading contributors to disease burden in this group in 2014 were 'cardiovascular diseases (30.3%), malignant neoplasms (15.1%), chronic respiratory diseases (9.5%), musculoskeletal diseases (7.5%), and neurological and mental disorders (6.6%).':549 In 2004, the World Health Organization calculated that 1.5 billion disability-adjusted life years were lost to disease and injury. The first study on the global burden of disease, conducted in 1990, quantified the health effects of more than 100 diseases and injuries for eight regions of the world, giving estimates of morbidity and mortality by age, sex, and region. It also introduced the DALY as a new metric to quantify the burden of diseases, injuries, and risk factors. From 2000–2002, the 1990 study was updated to include a more extensive analysis using a framework known as comparative risk factor assessment. In 2006, the WHO released a report which addressed the amount of global disease that could be prevented by reducing environmental risk factors. The report found that approximately one fourth of the global disease burden and more than one third of the burden among children was due to modifiable environmental factors. The 'environmentally-mediated' disease burden is much higher in developing countries, with the exception of certain non-communicable diseases, such as cardiovascular diseases and cancers, where the per capita disease burden is larger in developed countries. Children have the highest death toll, with more than 4 million environmentally-caused deaths yearly, mostly in developing countries. The infant death rate attributed to environmental causes is also 12 times higher in developing countries. 85 out of the 102 major diseases and injuries classified by WHO were due to environmental factors. To measure the environmental health impact, environment was defined as 'all the physical, chemical and biological factors external to a person, and all the related behaviours'. The definition of modifiable environment included: