Transcript Document 7199015

Nutrition and Health
surveys/nutrition monitoring;
Epidemiology
Chapters 5 & 7
History of epidemiology
• John Snow, 1854
– Cholera outbreak in London
– Snow had previously hypothesized cholera was
transmitted via water.
Two water companies in London
– One pulled water down stream from sewage,
one from up stream
– Deaths occurred around water pumps from the
downstream company
Practice of Epidemiology
• Epidemiology
– Initially used to investigate, control, and prevent epidemics
of infectious disease
• Epidemiologists work with other health professionals
– to identify causes of disease
– to propose strategies for controlling or preventing health
problems
• Can be used to describe a community’s health problems and to
determine whether health is improving or getting worse
• Surveillance methods have been used to monitor preventable
causes of birth defects
Epidemiology
• “the study of the distribution and
determinants of health-related states and
events in specified populations and the
application of this study to control of health
problems”
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Study—Epidemiology is the basic science of public health. It's a highly quantitative discipline based on principles of
statistics and research methodologies.
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Distribution—Epidemiologists study the distribution of frequencies and patterns of health events within groups in a
population. To do this, they use descriptive epidemiology, which characterizes health events in terms of time, place,
and person.
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Determinants—Epidemiologists also attempt to search for causes or factors that are associated with increased risk
or probability of disease. This type of epidemiology, where we move from questions of "who," "what," "where," and
"when" and start trying to answer "how" and "why," is referred to as analytical epidemiology.
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Health-related states—Although infectious diseases were clearly the focus of much of the early epidemiological
work, this is no longer true. Epidemiology as it is practiced today is applied to the whole spectrum of health-related
events, which includes chronic disease, environmental problems, behavioral problems, and injuries in addition to
infectious disease.
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Populations—One of the most important distinguishing characteristics of epidemiology is that it deals with groups of
people rather than with individual patients.
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Control—Finally, although epidemiology can be used simply as an analytical tool for studying diseases and their
determinants, it serves a more active role. Epidemiological data steers public health decision making and aids in
developing and evaluating interventions to control and prevent health problems. This is the primary function of
applied, or field, epidemiology.
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Basic Concepts
• Risk
“likelihood that people who are without a
disease, but exposed to certain risk
factors, will acquire the disease at some
point in their lives”
– Risk factors may be found in the physical
environment or social environment, or they
may be inherited.
– Other risk factors may be behavioral, such as
smoking.
Relative risk
• “Measure of how much a particular risk factor
influences the risk of a specified outcome”- to
identify differences in disease rates between
exposed and unexposed groups
• Relative Risk = Rate of condition among exposed divided by rate of
condition among unexposed
Incidence
• “the proportion of group initially free of a
disease that develops the disease over a
period of time”
Prevalence
• “the proportion of a group possessing a
disease at a specific time”
Epidemiological Method
•
Hypothesis testing
– Identify a cause-effect comparison to be
tested
• Explaining research observations
– Bias
– Chance
– Truth
Types of Epidemiologic Studies
• Ecological or Correlational Studies
– Compare the frequency of events in different
populations with the per capita consumption of certain
dietary factors.
– Dietary data collected in this type of study are usually
disappearance data, which are the figures for food
produced for human consumption minus the food that
is exported, fed to animals, wasted, or otherwise not
available for human consumption.
• Cross-sectional or Prevalence Studies
– Examine the relationships among dietary intake,
diseases, and other variables as they exist in
populations at a particular time.
Types of Epidemiologic Studies
• Cohort Studies
– A group of people, called a cohort, free from the
disease is identified and examined, and then followed
for months or even years
– Group members are examined periodically to
determine which individuals develop the
characteristics of interest and which do not.
- Retrospective - look back in time to reconstruct
exposures and health outcomes, or
- Prospective - those that follow a group into the
future.
Types of Epidemiologic Studies
• Case-Control Studies
– A group of persons with the disease is
compared with a group of persons without the
disease to compare characteristics, such as
previous exposure to a factor, between cases
and controls.
• Controlled Trials
– The most rigorous evaluation of a dietary
hypothesis is the randomized controlled trial
conducted as a double-blind experiment.
Nutritional epidemiology
• The epidemiologic method lends itself to
the study of the relationship of diet to
health and disease.
• The method can also be used to:
– Describe the nutrition status of populations or
specific subgroups of a population
– develop specific programs or services for
members of the group whose nutrition status
appears to be compromised.
– Evaluate nutrition interventions.
National nutrition policy
• - a set of nationwide guidelines that specify how the
nutritional needs of the population will be met.
• - there is no one federal body or agency with its sole
mandate to establish, implement, and evaluate national
nutrition policy.
• U.S. national nutrition policy
– Food assistance programs.
– National nutrition and health objectives.
– Regulations to safeguard the food supply and ensure safe
handling of food.
– Dietary guidance systems.
– Monitoring and surveillance programs.
– Food labeling legislation.
National Nutrition Policy
• Does the U.S. have a national
nutrition policy?
Why monitor nations health and
nutritional status?
• Nations monitor health and nutrition status
- to decide how to allocate scarce resources
- to enhance the quality of life
- to improve productivity
• Nutrition monitoring is a term that includes:
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Nutrition assessment
Nutrition monitoring
Nutrition surveillance
Nutrition screening
Background on Nutrition Monitoring
in the United States
• The U.S. government has been involved in tracking
certain elements of the food supply and food
consumption for more than 8 decades.
• The first USDA Household Food Consumption Survey 1930.
• The nation’s first comprehensive survey (Ten-State
Nutrition Survey) conducted between 1968 and 1970.
• In 1990 Congress passed legislation that established the
National Nutrition Monitoring and Related Research
Program (NNMRRP).
– It includes more than 50 surveillance activities that monitor and
evaluate the health and nutritional status of the U.S. population.
Types of data
• Primary data: relate directly to the
population served; often collected by the
acting agency itself
• Secondary data: relate to already existing
data in either published or unpublished
form
National Nutrition Monitoring
System
NNMRRP = National Nutrition
Monitoring and Related Research
Program
National Nutrition Monitoring and
Related Research Program
(NNMRRP)
• Established by Congress in 1990
• Implementation and coordination of
activities by USDA and DHHS
• Monitoring data are used to assess the
dietary, nutritional, and related health
status of the population
• More than 50 surveillance systems are
operative
NNMRRP Goals
• Collect, analyze, and disseminate data…
• Establish baseline data and uniform
standards
• Provide data to evaluate proposed policy
changes
NNMRRP Goals
• Provide scientific foundation
for improving nutritional status
and quality of food supply
• Identify high risk groups to aid
program planning
National Nutrition Monitoring
System
• Federally mandated collection and
analysis of data on:
– national food supply
– food composition
– food and nutrient consumption
– consumer knowledge, attitudes,
behaviors
– nutritional/health status
National Food Supply
• U.S. Food Supply Series
• Quantities available per capita of:
– food
– kcals available
– nutrients
USDA
Food Composition
• USDA Nutrient Data Base
• Used for:
– survey analysis
– research
– individual use
USDA
Food & Nutrient Consumption
• Ten State Survey
• Nationwide Food Consumption
Survey (NFCS)
• Continuing Survey of Food Intakes by
Individuals (CSFII)
USDA
• 5 A Day for Better Health
NCI…
Food and Nutrient Consumption
• “What We Eat in America Survey”
– Dietary interview component of NHANES
– Individuals in households, one sample with all
levels of income, another of low-income
households
– Two days of 24 hour dietary recall
– Times of eating occasions
– Sources of food eaten away from home
Food and Nutrient Consumption
• Total Diet Study (TDS)
– Eight age groups, infant through elderly
– Assesses for nutrients and contaminants
in foods
– Estimates levels of 11 essential minerals
– Collects and analyzes 234 foods from retail
markets in urban areas
KAB Assessments
• Behavioral Risk Factor Surveillance System (BRFSS)
• annually since 1984
• designed to examine trends over time.
• States can readily address urgent and emerging health issues.
• BRFSS questions focus on:
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Not getting enough physical activity
Eating a high-fat, low-fiber diet
Using tobacco and alcohol
Not getting medical care that is known to save lives
- e.g. mammograms, Pap smears, colorectal cancer screening, and flu
shots
- Food frequencies for dietary fat, fruit, and vegetable consumption
 CDC
• Youth Risk Behavior Survey (YRBS)
CDC
• Diet and Health Knowledge Survey (DHKS)
 USDA
Nutrition and Health Status
• National Health and Nutrition Examination Surveys
(NHANES I, II, III)
• “What we eat in America” (integration of NHANES &
CSFII)
• Hispanic Health and Nutrition Examination Survey
(HHANES)
 DHHS
• Pediatric Nutrition Surveillance System (PedNSS)
 CDC
Nutritional Status and NutritionRelated Health Measurements
• National Health and Nutrition
Examination Survey (NHANES) Series
– Representative sample of civilian
noninstitutionalized population ages 2 months
and older
– Dietary intake (one 24-hour recall)
– Body composition
– Biochemical analyses of blood and urine
– Bone density
– Dietary and health behaviors
– Collects data at household, family, and individual
level
Food Composition and Nutrient Data
Base
• National Nutrient Data Bank
(established in 1892) – updated on a
regular basis
– Nutrient content of foods
– Published tables of food composition
– Computerized databases
Food Composition and Nutrient Data
Base
• USDA Nutrient Data Base for Standard
Reference (initiated in 1980) – produced
from National Nutrient Data Bank
– Includes data on food energy, 28 food
components, and 18 amino acids for about
5,200 food items
– Main source of data for USDA Survey
Nutrient Data Base
Food Composition and Nutrient Data
Base
• USDA Survey Nutrient Data Base updated continuously
– Used for analysis of nationwide dietary
intake surveys
– Includes data on food energy and 28 food
components for >7,100 food items
Uses of NMRR Data
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___________ of dietary intake
Monitoring and Surveillance
Regulation
Food programs and Guidance
Scientific _________
Historical trends