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31 Cards in this Set
- Front
- Back
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why consider age?
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1.) Age is a risk factor for many outcomes
2.) Age is often associated with exposures as well 3.) Age is a good candidate for confounding |
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If a graph or tables shows that the prevalence of a disease decreases with age, does that mean that the prevalence rates do indeed decrease as individuals age?
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Not necessarily, long latency periods and cumulative effects of exposures can be the cause of seeing this trend.
-cumulative exposures: exposures accumulate over time. A daughter or son may have more exposures then his/her mother. -A person's health status at age 55 is dependent on his part exposures |
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What is a birth cohort?
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Looking at a period of birth and that period's characteristics-change with time and age.
-Variability of past exposures in birth cohorts can distort apparent associations between age and health outcomes. |
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What is age effect?
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Age effect is the change in the rate of a condition due to age, irrespective of birth cohort and calendar time.
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Cohort effect
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Cohort effect is the change in the rate of a condtion according to year of birth, irrespective of age and calendar time.
-may result from the lifetime experience fo individuals born at a given point in time that influences disease. -patterns of association between age and CHD may result from cohort effects related to changes in diet (fat intake) or smoking/alcohol habits of adolescents over time. |
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Period effect
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Change in the rate of a condition affecting an ENTIRE POPULATION at some point in time, irrespective of age and birth cohort.
-period effects on prevalences rates can occur when new meds of preventive interventions are introduced for diseases that previously had poor prognoses (e.g.,polio, insulin, antibiotics) -other phenomena that affect entire populations (e.g., war, a massive migration) |
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Ecologic studies
the unit of observation |
-the unit of observation is the group
-often, the unit of observation is a geographically defined population *mean values for a risk factor and outcome(s) of interest are compared -Resurgence of interest in ecologic studies lately due to social epidemiology |
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Types of studies
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1.) Type of study=ecologic
-Dependent variable: Group level -independent variable: Group level 2.) Type of study=Individual level -dependent variable: individual level -independent variable: independent level 3.) Type of study=Multilevel -Dependent variable: individual level -Independent variable: group and individual level |
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explanations for area differences
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-physical features of the environment shared by all residents (quality of air and water, climate, latitude)
-Availability of healthy environment at home, work and play -services provided to support people in their daily lives (education, transport, policing, welfare services) -sociocultural features of a neighborhood (norma and values, levels of crime, social capital, economic opportunity) -reputation of an area |
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Variables in ecologic studies
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Aggregate (compositional)
Enviromental (contextual) Global (contextual) |
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Aggregate variables in ecologic studies
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measures: summarize characteristics of individuals within a group as the mean values of a parameter (income)
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Enviromental variables in ecologic studies
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measures: represent physical characteristics of the geographic location (infrastructure)
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Global variables in ecologic studies
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measures: represent characteristics of the gorup not reducible to individuals (policies, income inequality, economic opportunity, segregation)
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Ecologic fallacy
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Bias that occurs when an investigator infers causality at an individual level using aggregate data.
*However, not all investigators are aimed at inferring causality at the individual level **There is value in examining the influence of aggregate-level factors on population health e.g., motor accidents and income Ecologic studies might be able to give us more clues are to what population motor accidents are occuring more in. This will narrow the scope for future studies |
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Disadvantages to ecologic studies
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-Cannot control for confounding at the individual level
-tend to be cross-sectional in nature -cannot infer causality at the individual level *multi-level modeling (heirarchical modeling, mixed level modeling) allows for sumultaneous influnce of individual and aggregate level variables |
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Advantages of ecologic studies
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-efficient, inexpensive
-allow examination of the contribution of aggregate level variable to health outcomes -allow examination of multiple exposures, multiple health outcomes -can be used to generate hypotheses -useful when within-population variability of exposure of interest is low but between-population variability is high (used to compare different communities, different classrooms) |
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What is population health?
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-"The health of a population as measured by health status indicators and as influenced by social, economic and physical environments, personal health practices, individual capacity and coping skills, human biology, early childhood development and health services."
*this term has been used with greater frequency in recent years, but a precise definition is not agreed upon. **some people argue population health is not an outcome but rather a field of study ***populations may be geographic resions, such as nations or communities, but can also be groups (prisoners, employees). These groups are of relevance to policymakers. |
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Field of population health
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Focuses on interrelated factors that influence the health of populations over the life course, identifies systematic variations in their patterns of occurrence, and applies then resulting knowledge to develop and implement policies and actions to imporve the health of those populations.
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Outcomes of population health stategies
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The outcomes of population health strategies extend beyond improved health status to include wider social, economic and enviromental benefits.
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What are fundamental determinants?
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They are:
-Products of the social, economic, and physical environment -factors influence risk factors and health outcomes by shaping health behavior and by shaping access to resources and conditions |
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Social and economic environment determinants:
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Education
income occupation social support discrimination social capital early childhood experience |
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Fundamental determinants: the physical environment
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housing conditions
clean air and water availability of transportation health care, human service, and food availability |
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Social+Economic+Physical Factors
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These factors work together in concert with biological endowment to:
-shape how an individual responds to her life's challenges -confer health capital -facilitate of hinder productivity and the acquisition of health **Population health is concerned about the interactions between these factors (social, economic, physical and biological response) |
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Health capital
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is a dynamic product of health promoting inputs and health depleting experience. This concept is similar to that of the human capital theory.
Health as an output and the health care system as one of the inputs similar to the human capital model which says that the more a person invests in job training, education, etc, the more that person will contribute to society and productivity. Health capital is similar, the more health input, the better the health output. |
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Traditional epidemiologic approach
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Focused on identification of individual level risk factors in prevention of disease
-behavior is a proximal determinant -social and physical factors are more distal or fundamental in chain of causation |
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Example, Myocardial infarct
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From the perspective of prevention, the clogges artery is nearly usefless as a cause. It is so temporally proximate to the event that the opportunity to intervene is limited.
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population perspective
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An individual's risk of illness cannot be considered in isolation from the disease risk of the population to which she belongs.
-Risks distributed among continuum, with small shift in distribution of risk throughout a population making large difference in health status of that population |
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Rose, 1985 paper
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strongly influence of later developments
-his article "sick individuals and sick populations" |
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In Western Industrialized nations, the entire bell curve of cholesterol levels is shifted due to dietary factors, so even "low levels" within the population confer CHD risk.
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Thus a large number of people at small risk give rise to more cases of the disease than the smaller number who are at high risk.
In this example in the slides. the two bell curves being compared are that of Finland and the US. |
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In order to substantially reduce a population's level of chronic disease:
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One needs to seek the causes that shift entire risk factor distributions (obesity, eating habits) at the population level, not simply the "causes of the cases" at the individual level.
In PUBLIC HEALTH, we are interested in causal factors so as to have policy and changes implements to PREVENT disease. |
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Understanding why some populations have certain distributions leads to very different etiologic questions besides asking why some of the individuals are in the tails of the distribution.
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Be sure to know the differences between the advantages of looking at population health versus individual health.
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