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NUTRITIONAL EPIDEMIOLOGY The study of eating behavior and

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NUTRITIONAL EPIDEMIOLOGY The study of eating behavior and how it influences the etiology, occurrence, prevention, and treatment of disease. Epidemiology Uses ... – PowerPoint PPT presentation

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Title: NUTRITIONAL EPIDEMIOLOGY The study of eating behavior and


1
NUTRITIONAL EPIDEMIOLOGY
  • The study of eating behavior and how it
    influences the etiology, occurrence, prevention,
    and treatment of disease.

2
Epidemiology
  • Uses biostatistics, statistical processes and
    methods applied to the analysis of biological
    phenomena, to describe and quantitate health
    events and the factors that place individuals at
    risk for health events.

3
Epidemiology
  • It began as an approach to control communicable
    disease.
  • The methods and principles have been applied
    successfully to improve our understanding of
    chronic disease.
  • It is the basic science for public and community
    health.
  • Baseline data are used as the foundation for
    program planning.

4
Nutritional Epidemiology
  • Focuses on eating behavior and how that behavior
    influences health status, disease morbidity, and
    mortality.
  • These approaches are in contrast to clinical
    medicine, which focuses on diagnosing and
    treating sick people.

5
The Territory of Epidemiology-Principles and
Application
  • Epidemiologic methods are tools to explore
    disease occurrence, treatment, prevention, and
    cure.
  • A traditional model explores the causes of an
    infectious disease, using three components an
    agent (microbe, chemical, behavior,), a host
    (host factors include age, ethnicity, sex, SES,
    eating patterns,), and an environment conducive
    to linking the first two components (geology,
    climate, housing conditions,).

6
Levels of Epidemiologic Research
7
Types of Studies
  • Either controlled (experimental) or uncontrolled
    (observational).
  • Controlled studies mean that an artificial or
    planned situation exists.

8
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9
Uncontrolled Studies
  • Cross-Sectional Studies
  • Snapshot look at the population at one point in
    time.
  • Represent a sample from a population.
  • Cannot explore or test cause and effect.
  • Can assist with formulating public health
    education and intervention programs.
  • Examples National Health and Nutrition
    Examination Survey (NHANES)in the US, Lebanon
    Maternal and Child Health Survey (PAP Child).
  • Provide data to calculate prevalence rates.

10
Cross-Sectional Studies
  • Provide quick snapshot look.
  • Have low cost (can use telephone, mail).
  • Define prevalence.
  • Determine association between variables
    (independent and dependent).
  • Generate hypotheses.

11
Cross-Sectional Studies
  • Cannot establish cause and effect.
  • Use live individuals (problems of data
    collection).
  • Are insensitive to rare characteristics.
  • Requires a sample or subsample of a population.
  • Describe current, not past or future events.

12
Uncontrolled Studies
  • Case-Control Studies
  • Retrospective approach compares cases and
    controls for the presence of antecedent
    variables.
  • Require that cases and controls come from similar
    populations.
  • Cases must have the health outcome (disease),
    they must be similar in all other aspects.
  • The confounding effect of a variable can be
    avoided by selecting cases and controls of the
    same age, ethnicity, and gender (matching)
  • Commonly used statistic is relative risk or odds
    ratio

13
Case-Control Studies
  • Cases are easily available in clinical settings.
  • They are relatively quick and inexpensive.
  • Results support, but do not prove, causal
    hypotheses.
  • Secondary analyses are possible (records
    available).
  • Sample size is small.
  • Study of rare diseases is possible.

14
Case-Control Studies
  • Data are from memory, increasing bias.
  • Records may be inadequate.
  • Criteria for diagnoses may vary among clinicians.
  • Cases are selective survivors.
  • Cases may not be representative because coming
    from treatment. Antecedent data reflect only
    living cases.

15
Uncontrolled Studies
  • Cohort Studies
  • Prospective studies that can project risk
    estimates for future events.
  • Cohort is followed over time.
  • Results can be provided to decision makers.
  • Confirm causation.
  • Relative risk can be calculated

16
Cohort Studies
  • Increase potential for confirmation of cause and
    effect.
  • Quantify extent of effect due to risk factor.
  • Provide baseline rates for new cases in a
    community.
  • Estimate prevalence.
  • Allow for hypothesis testing.
  • Participant cooperation is high.

17
Cohort Studies
  • Reduce information bias.
  • Minimize selection factors, since all members of
    the cohort are disease-free.
  • Follow original cohort even if individuals
    relocate.

18
Cohort Studies
  • Require a long observation period.
  • Loss to follow-up occurs, which creates selection
    bias.
  • Expensive
  • Ecological changes can affect and/or create
    associations and outcomes.
  • Rare diseases cannot be studied.

19
Controlled (Experimental) Studies
  • Investigators control over assignment of
    individuals to groups (random assignment).
  • Randomization ensures comparability of
    individuals and groups to all known and unknown
    factors except the one studied.

20
Controlled (Experimental) Studies
  • Experiment evaluates what occurs after exposure
    to a risk factor.
  • An intervention group receives an intervention,
    and a control group does not.
  • Comparison is carried out between the two groups.
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