Chapter 2 Health Determinants, Measurements, and Trends Richard Skolnik
The Importance of Measuring Health Status In order to address global health issues, we must understand: • The factors that most influence health status • The indicators used to measure health status • The trends that have occurred historically
Figure 2.1: Key Determinants of Health Data from: The Public Health Agency of Canada. What Determines Health. Available at: http://www.phac-aspc.gc.ca/ph-sp/determinants/index-eng.php#determinants. Accessed November 19, 2010.
Key Health Status Indicators Health status indicators are useful for: • Finding which diseases people suffer from • Determining the extent to which the disease causes death or disability • Practicing disease prevention/interventions To perform these functions, it is important to use a consistent set of indicators and have accurate data
Key is a Vital Registration System • Vital registration systems record births, deaths, and causes of death • An accurate system is key to having quality data on a population • Many low- and middle-income countries lack a vital registration system • Developing a system is progress towards understanding and addressing health problems
Key Health Status Indicators • Neonatal mortality rate • # deaths of infants under 28 days of age per 1000 births in a year
Figure 2.4: Neonatal Mortality Rate, by WHO Region, 2004Trends in neonatal mortality – more recent data Data from World Health Organization. Neonatal and Perinatal Mortality: Country, Regional, and Global Estimates 2004. Geneva: WHO; 2007: Table 2.
Neonatal Mortality • One quarter to one half of all deaths occur within the first 24 hours of life • 75% of deaths occur in the first week • The 48 hours immediately following birth is the most crucial period for newborn survival • A baby's chance of survival increases significantly with the presence of a skilled birth attendant at the birth WHO
Key Health Status Indicators • Infant mortality rate • # deaths of infants in the first year of life per 1000 births in a year
Figure 2.3: Infant Mortality Rate, by World Bank Region, 2008 Data from The World Bank. World Development Indicators, Data Query. Available at: http://databank.worldbank.org. Accessed June 29, 2010.
Key Health Status Indicators • Under 5 mortality rate • aka child mortality rate • the probability that a newborn infant will die before reaching the age of 5, # per 1000 live births
Figure 2.5: Under-five Child Mortality Rate, by World Bank Region, 2008 Data from The World Bank. World Development Indicators, Data Query. Available at: http://databank.worldbank.org. Accessed June 29, 2010.
Under 5 Mortality - WHO • 6.9 million children under the age of five died in 2011. • More than half of these early child deaths are due to conditions that could be prevented or treated with access to simple, affordable interventions.
Under 5 Mortality - WHO • Leading causes of death: • pneumonia, preterm birth complications, diarrhea, birth asphyxia and malaria • ~ one third of all child deaths are linked to malnutrition. • Children in sub-Saharan Africa are about 16.5 times more likely to die before the age of five than children in developed regions.
Key Health Status Indicators • Neonatal mortality rate - # deaths of infants under 28 days of age per 1000 births in a year • Infant mortality rate - # deaths of infants in the first year of life per 1000 births in a year • Under 5 mortality rate (aka Child mortality rate) – the probability that a newborn infant will die before reaching the age of 5, # per 1000 live births
Key Health Status Indicators • Maternal mortality rate • # women who die as a result of pregnancy or childbirth complications per 100,000 live births in a year
Figure 2.6: Maternal Mortality Ratio, by World Bank Region, 2005 Data from The World Bank. World Development Indicators, Data Query. Available at: http://databank.worldbank.org. Accessed June 29, 2010..
Worldwide Data – Maternal Mortality • 87% deaths in Sub-Saharan Africa and South Asia • 50 percent of all deaths occurred in six nations: India, Nigeria, Pakistan, Afghanistan, Ethiopia, and the Democratic Republic of Congo
Key Health Status Indicators • Life expectancy at birth • average # of years a newborn could expect to live if current mortality rates were to continue for the rest of the infant’s life
Figure 2.2: Life Expectancy at Birth, by World Bank Region, 2008 Data from the World Bank. World Development Indicators, Data Query. Available at: http://databank.worldbank.org. Accessed June 29, 2010.
Table 2.11: Life Expectancy and Percentage Gain in Life Expectancy, 1960-2008, by World Bank Region Historical Trends based on Health Status Indicators Data from the World Bank. World Development Indicators, Data Query. Available at: http://databank.worldbank.org. Accessed July 6, 2010.
Worst country for women & children – Afghanistan • 14% of births are attended by a health professional • Lifetime risk of woman dying as a result of pregnancy or childbirth: 1 in 11 • Life expectancy girl born today = 45
Afghanistan • Under 5 mortality rate: 1 in 5 children die before the age of 5 • Every woman is likely to suffer the loss of a child in her lifetime • 39% of children moderately or severely underweight • 52% Do not have access to clean water
Key Terms • Morbidity – sickness/illness • physiological and/or psychological • Mortality – death • Mortality/Death rate expressed as # deaths per 1000 in a population in a year • Disability – “temporary or long-term reduction in a person’s capacity to function”
Key Terms • Prevalence - # of people suffering from a particular health condition over a period of time • Generally consider at a given point in time (cross-sectional) – point prevalence • Measure of existing cases at a given time • Incidence rate - # of people contracting a disease per 1000 at risk in a year • Measure of new cases per year
Classification of Diseases • Communicable diseases – spread by an infectious agent • Influenza, HIV/AIDS, measles, malaria, cholera • Non-communicable diseases – diseases not spread by an infectious agent • Hypertension, diabetes, lung cancer, CVD • Injuries • Accidents, violence, burns, cuts
Figure 2.10: The Burden of Disease by Group of Cause, Percent of Deaths, 2001 Data from Lopez AD, et al Global Burden of Disease and Risk Factors. Washington, DC and New York: The World Bank and Oxford University Press; 2006:8.
Table 2.10: The "Demographic Divide:" The Example of Nigeria and Japan Data from PRB. 2009 World Population Data Sheet. Available at http://www.prb.org/Publications/Datasheets/2009/2009wpds.aspx. Accessed November 24, 2010.
The Global Burden of Disease Causes of Death by Region • Higher income countries tend to have a greater burden of non-communicable disease • Lower income countries to have a greater burden of communicable disease
The Global Burden of Disease Causes of Death by Age • Children in low- and middle-income countries often die of communicable disease • HIV/AIDS and TB are among the leading causes of death among adults in low and middle-income countries
Table 2.5: The 10 Leading Causes of Death in Children Ages 0-14, by Broad Income Group, 2001
Table 2.6: The 10 Leading Causes of Death in Adults 15-59, by Broad Income Group, 2001
The Global Burden of Disease In most low- and middle-income countries: • Rural people will be less healthy • Disadvantaged ethnic minorities will be less healthy • Women will suffer as a result of their social positions • Poor people will be less healthy • Uneducated people will be less healthy
Measuring the Burden of Disease • Two indicators used to compare how far countries are from a state of good health • Health-Adjusted Life Expectancy (HALE)- summarizes expected number of years to be lived in what might be termed the equivalent of good health • Disability-Adjusted Life Year (DALY)- a unit for measuring the amount of health lost because of a particular disease or injury
Measuring the Burden of Disease • HALE – Health-Adjusted Life Expectancy • Calculated by a standard methodology by World Health Organization (WHO) • Years of ill health are weighted according to severity and subtracted from overall life-expectancy
Table 2.2: Life Expectancy at Birth and Health-Adjusted Life Expectancy,, 2004 Data from WHO. Core Health Indicators. Available at: http://www3.who.int/whosis/core/core_select_process.cfm. Accessed: September 24, 2006.
DALY – Disability Adjusted Life Year • First measured by World Bank as a “health gap measure” • Used by World Bank and WHO – controversial measure • DALYs are thought to be a better indicator of the health of a population than mortality rates • DALY takes into account that many conditions associated with poor health are not fatal • A higher DALY value indicates a greater health burden
DALYs • “This time-based measure combines years of life lost due to premature mortality and years of life lost due to time lived in states of less than full health. • The DALY metric was developed in the original Global Burden of Disease 1990 study to assess the burden of disease consistently across diseases, risk factors and regions.”
DALYs • A DALY is a measure of years of fully healthy life lost due to disease, death, …….disability….. • The higher the DALY value the more years lost due this “condition” – or the more years living with compromised health
DALYs • DALYs are intended to provide a comparable measure of the burden of disease • Used to: • Aid in setting health care priorities • Treatment and prevention • Aid in setting research priorities • Identify high need populations and target health interventions • Measure success/effectiveness of interventions
DALYs…put another way • Measures how many healthy years of life are lost between the population being studied and the healthiest possible populations • Consider • Communicable diseases • Maternal, perinatal (1st weeks after birth) • Nutritional disorders • Non-communicable disorders • Injuries/accidents Grouped together
Table 2.3: The 10 Leading DALYs Low and Middle-Income High-Income Countries Table 2-4 on page 30 shows DALYs in low and middle-income countries by regions
Calculating DALYs • Disabilities/health conditions are weighted by one of 6 values based on the limitations or reduction in years of life associated with the “condition” • The more serious the “condition” the higher the weighting • Deaf, weighting = .33 • Dead, weighting = 1 (most serious!) • Calculating DALYs
WEIGHTING of DISABILITIES • Weightings quantify societal preferences for health states in relation to the societal ideal of good health. • On average, society judges a year with blindness (weight 0.43) to be preferable to a year with paraplegia (weight 0.57), and a year with paraplegia to be preferable to a year with unremitting unipolar major depression (weight 0.76). • Source this slide and next http://www.who.int/quantifying_ehimpacts/publications/en/9241546204chap3.pdf
WEIGHTING of DISABILITIES • On average, society would prefer a person to have a year in good health followed by death, than a year with paraplegia followed by death. • Society would prefer a person to live three years with paraplegia followed by death (3 years x 0.57 = 1.7 lost “healthy” years), than have one year of good health followed by death (2 lost years of good health).