TEST YOUR KNOWLEDGE OF PUBLIC HEALTH
- Mortality from diabetes and AIDS
- Epidemiological transition
- Cancer incidence & prevalence
- Maternal mortality
- Causes of child death in Sub-Saharan Africa
- Violent conflict and health
- Extreme poverty
- Primary school attendance
- U.S. infant mortality rates
- U.S. asthma rates
- Infectious disease control
- Primary, secondary and tertiary healthcare
- Health expenditures and health outcomes
- Socioeconomic status & health
- Equity or equality in access
2. Infectious diseases impose a greater health burden than chronic diseases do.
The global burden of disease is shifting from infectious diseases to one dominated by chronic diseases.
The shift is happening in both rich and poor nations. Poor countries burdened by infectious disease are now experiencing a “double burden” of disease as larger numbers of people are also affected by cardiovascular disease, cancer, and the like.
© 2007 Carl Whetham, Courtesy of Photoshare
The graph below represents the World Health Organization’s (WHO) estimates for the distribution of deaths in 2004 from three categories of disease: noncommunicable; communicable, maternal, perinatal & nutritional; and injuries. (See graph below.)
Percent total deaths by gender and disease category
There are regional differences in the distribution of deaths from the three WHO categories of diseases. (See graph below.)
Number of deaths by disease category, region and gender
That said, even in Africa, the only region where noncommunicable diseases are responsible for less than half of deaths, they still represent a substantial portion of the disease burden.
This shift in burden does not mean that infectious diseases and their control can be ignored. The United States saw an increase in deaths due to infectious diseases during the 1980s and 1990s, which the U.S. Centers for Disease Control and Prevention (CDC) attribute to complacency on the need for continued surveillance and research into treatment and control of infectious diseases. Future concerns are treatement and control of new infectious diseases; overcoming drug resistance to current treatments for infection; prevention and treatment of food borne illnesses; and bioterrorism. (See Question 11 for more on control of infectious diseases.)
Measures of disease burden
However, the burden created by disease and injury includes more than just the premature deaths discussed above. Noncommunicable diseases may cause substantial disability and lower quality of life. Efforts to capture these factors in addition to morbidity and mortality rates lead to the creation of several, different measures of disease burden. HALY, or health-adjusted life year, is an umbrella term covering this "family of measures," including the DALY, the HALE and the QALY (Gold et al., 2002). We offer a brief description of these three.
The disability-adjusted life year (DALY) measures healthy life lost to disease and injury. DALY estimates add together two measures: years of life lost plus years lost to disability. The WHO website offers more on this estimate of health and well-being, including weighting for age and disability.
Healthy life expectancy (HALE) at birth (in years) uses the opposite perspective from DALY. It estimates not the burden of disease but the average number of years that a person can expect to live free of disease or injury. It is estimated using data on disease prevalence and severity and on life expectancy. HALE does not identify disease-specific impact but captures an individual's overall experience of heath.
The quality-adjusted life-year (QALY) takes “into account both the quantity and quality of life generated by healthcare interventions” (Phillips 2009, 1). This estimate incorporates life expectancy and quality of life and was initially developed as a tool to evaluate the cost effectiveness of health interventions (Gold et al., 2002).
A Bowling. Health-related quality of life: A discussion of the concept, its use and measurement background: the 'Quality of life.' Washington, DC: World Bank, 1999.
MR Gold, D Stevenson & DG Fryback. "HALYs and QALYs and DALYS, Oh My: Similarities and differences in summary measures of population health." Annual Review of Public Health 23 (2002): 115-134.
AD Lopez et al. Global Burden of Disease and Risk Factors. Washington DC & New York: Oxford University Press and The World Bank, 2006.
CD Mathers et al. "Methods for Measuring Healthy Life Expectancy." Health systems performance assessment: debates, methods and empiricism. Eds. CJL Murray & D. Evans. Geneva: World Health Organization, 2003.
CJL Murray & AD Lopez. "Alternative projections of mortality and disability by cause 1990-2020: Global Burden of Disease Study." The Lancet 349.9064 (24 May 1997): 1498-1504.