The Science Behind the Science

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The Science Behind the Science
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• Incidence the number of new cases of a disease
  or condition
• Prevalence the total number of cases of a
  disease or condition

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Observational Studies

• Case-Control
• Persons with disease
• Comparison group
• Cohort
• Subjects classified on basis of exposure of a
  factor
• Follow-up to determine presence of disease
• Prospective vs. retrospective

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Case-control Studies

• Exposed
• Study Non-Exposed
• Sample Exposed
• Non-Exposed
• Time
• Examples
• Oral contraceptives and breast cancer
• Superabsorbant tampon use and toxic shock
  syndrome
• Coffee consumption and pancreatic cancer
• Sleeping position and SIDS

Diseased
Non-Diseased
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Case-control Studies (Cont.)

• Advantages
• Uniquely suited to diseases with long incubation
  periods
• More efficient in terms of time and money
• Good for study of rare disease

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Case-control Studies (Cont.)

• Disadvantages
• Cannot show causality
• Particularly prone to recall bias

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Cohort Studies

• Study
• Sample
• Time
• Examples
• Smoking and Lung Cancer
• Other Framingham Study, Nurses Health Study
• Bogalusa Childrens Study

Diseased Non-Diseased Diseased Non-Diseased
Exposed
Non-Exposed
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Types Of Cohort Studies

• PROSPECTIVE
• Study starts in the present and investigator
  observes cohort prospectively (i.e. into the
  future)
• Advantage Can collect whatever information you
  want
• RETROSPECTIVE
• Investigator identifies cohort retrospectively
  (i.e. in the past) and observes cohort through
  historical time
• Disadvantage You're stuck with what information
  was collected in the past

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Cohort (Cont.)

• Advantages
• Can measure incidence and risk
• No recall bias
• Exposure precedes disease
• Can study several diseases

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Cohort (Cont.)

• Disadvantages
• Large number of subjects/participants
• Inefficient for rare diseases
• Long follow-up period
• Subjects may change health behaviors during
  course of study
• Possible changes over time in ascertainment of
  disease
• Very costly

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Example Prospective

• Moderate Alcohol Consumption and the Risk of
  Breast cancer (Willet et al. 1987).
• Population
• Nurses Health Study (N89,538) RNs
• Ages 34-59
• Follow-up
• Entry in 1980, followed until 1984
• 601 cases of breast cancer by 1984

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Alcohol Consumption and Breast Cancer
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Bogalusa Children Study

• Heart disease starts in children and is evident
  at 5-8 years of age
• Poor diet and sedentary living lead to healthy
  risks which lead to disease
• Lifestyles and behaviors are learned early in
  life
• Chronic disease prevention in adults should begin
  in childhood

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Calculation of Relative Risk

• w disease w/o disease
• Exposed a b total(ab)
• Not-Exposed c d total(cd)
• Relative risk w/disease in exposed group
• w/disease in not-exposed group

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An Example of Relative Risk

• w cancer w/o cancer
• Bad diet 350 650
  total(350650)
• Good diet 100 900
  total(100900)
• RR w/disease in exposed group (350/1000)
• w/disease in not-exposed group (100/1000)
• .35 3.5
• .10

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Calculation of Relative Risk

• Those with a bad diet have 3.5 times the risk of
  cancer as compared to those with a good diet.
• Those with a good diet have .28 (.10/.35) times
  the risk of cancer as compared to those with a
  bad diet.

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Relative Risk

• A measure of how much a particular risk factor
  (like high body fat) influences the risk of a
  specified outcome (such as diabetes)
• Relative risk 2
• Persons with a relative risk factor of 2 have a 2
  fold increased risk of having a specified outcome
  compared to persons without that risk factor.
• Relative risk .5
• Persons with a relative risk factor of .5 have
  half the risk of having a specified outcome
  compared to persons without that risk factor.

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Risk of death by body weight and activity
Risk of CVD/cancer death
Hu, NEJM 20043522694
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Risk of dementia (Alzheimers) by risk factors
(high blood pressure, cholesterol, smoking, or
diabetes)
Risk of dementia
Neurology, 2005,64277-281
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• Nut and peanut butter consumption and risk of
  type 2 diabetes in women.
• Jiang R, Manson JE, Stampfer MJ, Liu S, Willett
  WC, Hu FB.
• Nuts are high in unsaturated (polyunsaturated and
  monounsaturated) fat and other nutrients that may
  improve glucose and insulin homeostasis.
• OBJECTIVE To examine prospectively the
  relationship between nut consumption and risk of
  type 2 diabetes.
• DESIGN, SETTING, AND PARTICIPANTS Prospective
  cohort study of 83 818 women from 11 states in
  the Nurses' Health Study. The women were aged 34
  to 59 years, had no history of diabetes,
  cardiovascular disease, or cancer, completed a
  validated dietary questionnaire at baseline in
  1980, and were followed up for 16 years.
• MAIN OUTCOME MEASURE Incident cases of type 2
  diabetes.

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• RESULTS We documented 3206 new cases of type 2
  diabetes. Nut consumption was inversely
  associated with risk of type 2 diabetes. The
  relative risks (RRs) across categories of nut
  consumption (never/almost never, ltonce/week, 1-4
  times/week, and gt or 5 times/week) for a 28-g (1
  oz) serving size were 1.0, 0.92 (95 confidence
  interval CI, 0.85-1.00), 0.84 (0.95 CI,
  0.76-0.93), and 0.73 (95 CI, 0.60-0.89) (P for
  trend lt.001). Consumption of peanut butter was
  also inversely associated with type 2 diabetes.
• CONCLUSIONS Our findings suggest potential
  benefits of higher nut and peanut butter
  consumption in lowering risk of type 2 diabetes
  in women. To avoid increasing caloric intake,
  regular nut consumption can be recommended as a
  replacement for consumption of refined grain
  products or red or processed meats.

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Risk of type II diabetes and nut consumption (1oz)
Risk of type II diabetes
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Lycopene and Cancer Death Relative Risk
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Intervention Studies

• Experimental studies - clinical trials
• Provides most reliable evidence
  (causality-tobacco industry)
• Randomization
• Controls for known risk factors
• Controls for unknown risk factors
• Useful for studying small to moderate effects
• Ethical considerations
• Human rights review

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Statistical testing

• Every statistical test gives you a statistic (a
  number) and a p value
• p value is the probability that what you found
  was not due to chance. Scientists have decided
  to use .05 as an acceptable level of confidence
• Meaningfulness is not the same as significant

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• Meaningfulness is arbitrary, but important.
• How meaningful is the result?

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Lifestyle Research Initiative

• 1.4 million
• Randomized lifestyle trial
• 700 people
• 6 week lifestyle intervention program
• Outcomes to include healthy lifestyle knowledge
  and behavior, CVD risk factors, body fat,
  glucose, HbA1C, serum antioxidant capacity, bone
  metabolism and many others

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Data collection..

• Intervention group measured at
• Baseline
• 6 weeks
• 6 months
• 12 months
• 18 months

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• Control group measured at
• Baseline, 6 weeks, and 6 months
• At 6 months control group started the lifestyle
  intervention

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Number of participants
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Total Steps/week
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Calories Consumed
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Courtesy of Dr. Kelly Brownell
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Meat Servings/day
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Percent Calories from Fat
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Grams of Saturated Fat/day
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Grams of Monounsaturated Fat/day
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Grams of Polyunsaturated Fat/day
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Grams of Fiber/day
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Fast Food Reaches Africa
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Vegetable Servings/day
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Fruit Servings/day
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Grain Servings/day
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Dairy Servings/day
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Dietary Cholesterol mg/day
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Dietary Cholesterol mg/day
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Weight in pounds
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16 oz
32 oz
44 oz
52 oz
64 oz
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Percent Body Fat
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BMI
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BMI changes at 6 weeks
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BMI changes at 6 months
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Systolic Blood Pressure
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Systolic Blood Pressure Reductions at 6 weeks
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Systolic Blood Pressure Reductions at 6 months
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Diastolic Blood Pressure
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Diastolic Blood Pressure Reductions at 6 weeks
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Diastolic Blood Pressure Reductions at 6 months
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Total Cholesterol mg/dl
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Total Cholesterol Reductions at 6 weeks
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Total Cholesterol Reductions at 6 months
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Reductions in risk

• There is a 2-3 decrease in MI risk for
• Every 1 mmHg decrease in diastolic
• Every 1 decrease in total CHL

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Changes is Diastolic BP and CHL

• Diastolic BP mmHg
• Ideal -3.5
• High -10.4
• Dangerous -14.0

• Total CHL decr.
• Normal -9.2
• Borderline -13.2
• High -17.9

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Reductions in risk with these changes

• Diastolic BP
• Ideal 7-11
• High 21-31
• Dangerous 28-42

• Total CHL
• Normal 18-28
• Borderline 26-40
• High 36-54

64-96 reduction in heart disease risk
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HDL mg/dl
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HDL Cholesterol Changes at 6 weeks
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HDL Cholesterol Changes at 6 months
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LDL mg/dl
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LDL Cholesterol Reductions at 6 weeks
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LDL Cholesterol Reductions at 6 months
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Triglycerides mg/dl
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Triglyceride Changes at 6 weeks
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Triglyceride Changes at 6 months
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Blood Glucose mg/dl
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Glucose Reductions at 6 weeks
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Glucose Reductions at 6 months
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CHIP Meeting
CHIP Team
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CHIP Bus Trip Healthy Shopping
CHIP Picnic
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CHIP Dancing to a Healthier YOU!
CHIP Walkers!
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Demonstrating how to pick good Fruits and
vegetables
Senior Olympic Stars! Setting State and
Local Records in several events!
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Observing the chefs at work!
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Feasting at local CHIP Restaurant Octane
Great food in preparation
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Bringing Healthy food to the public and having
fun doing it!
On the Waterfront goes HEALTHY!!
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Massage Time!