epi part 2

Experimental

Deliberate manipulation of the cause is predictably followed by an alteration in the effect not due to chance

Analytic

Further studies to determine the validity of a hypothesis concerning the occurrence of disease.

Other Major Sources of Descriptive Public Health Data: • National Health Interview Survey - Gathers national data on major health problems including acute illnesses and injuries, chronic illnesses and impairments, and utilization of health services

National Survey of Family Growth is a Sampling Survey only. And so is the National Health...doesn't look at everyone.

Sources of Public Health Data: - Information is obtainable on deaths and a wide variety of diseases and conditions including acute illnesses and injuries, chronic illnesses and impairments, birth defects and other adverse pregnancy outcomes. - Information is also available on characteristics that influence a person's risk of illness such as nutritional habits, immunizations, and the use of cigarettes, alcohol and drugs.

Now we report on a lot of disease and deaths. We have to report deaths by law and there are certain diseases that have to be reported by law. HIV/AIDS is required...some that have registries like tumor registers and also those that include acute illnesses and birth defects, and things of those nature. And we have data not just on the disease but certain risk factors as well for disease.

PARAMOUNT STUDIES: HARVARD ALUMNI: - 10,000 males from mid-1960s-1977 - ____- was shown to reduce the likelihood of developing physician diagnosed depression

Physical activity

Sources of Public Health Data: • There is a wealth of information on the health status of the U.S. population. • Most data are collected by governmental and non-governmental agencies on a routine basis or by special surveys. • There are also several sources of international data that contain information on births, deaths, and major health indicators.

So where does our data come from? The US population has a lot of data collected on it. Most are collected from government and non government agencies. They collect it on a regular basis or they want to know something special. Some non-government would be the Robert Wood Johnson, insurance companies.

Descriptive

Study of the occurrence and distribution of disease uses prevalence; used beforehand to help make hypothesis

Introduction: - These data can be used to estimate the relative risk. - We have just identified cases of disease from a defined population, and then taken a sample of that population for comparison. Exposure histories are determined for each group. This is an example of the case-control method of sampling.

4 controls for every case- power

Introduction: - Hypothesis: Elevated levels of TNF-alpha increases the risk of Type 2 Diabetes Mellitus. - Consider a hypothetical prospective cohort study of 89,949 women aged 34-59; 1,439 type 2 diabetes cases identified over 8 years of follow-up - Blood drawn on all 89,949 at beginning of follow-up and frozen - Exposure: Level of TNF-alpha in blood characterized as high or low Relative Risk = RR = (360/13,636) / (1,079/76,313) = 1.9

70% of epi studies is casecontrol studies

Hypothalamic Pituitary-Adrenal (HPA) axis: Best known for its role in our body's reaction to stress PA decreases release of - _____ from the hypothalamus - _____from the anterior pituitary

CRH ACTH

Standardized Rate: • A weighted average of the ________ rates • The weights are taken from the _______ - it can be one of the age distributions to be compared - it can be a combined age distribution, or - it can be any other age distribution that is of interest *there will be a standardization prob on final

category-specific standard distribution

Principles of Experimental Studies Applied to Observational Cohort Studies: 1. Randomization of treatment so groups are comparable on known and unknown confounders. Can't randomize in an observational study so select a comparison group as alike as possible to the exposed group 2. Use placebo in order to reduce bias. Can't use placebo in observational studies so you must make the groups as comparable as possible. 3. Blinding to avoid bias in outcome ascertainment. In a cohort study, it is crucial to have high follow-up rates and comparable ascertainment of outcomes in the exposed and comparison groups. You can blind the investigators conducting follow up and confirming the outcomes.

comparison group needs to not exposed and dont have the disease

• What are the issues in using an experimental study design for this question?

compliance issues- are they actually doing what they are supposed to

Why do we care about decreasing anxiety and depression? Why is it a public health concern?

next slide answers

Risk Difference and Standardization of Rates: Two Main Options for Comparison: 1. Calculate ____ of two measures of disease frequency (a measure in exposed group and a measure in unexposed comparison group) 2. Calculate ______ between two measures of disease frequency (a measure in exposed group and a measure in unexposed comparison group)

ratio, difference

TROHOC" STUDIES: - This disparaging term was given to case-control studies because their logic seemed backwards (trohoc is cohort spelled backwards) and they seemed more prone to bias than other designs. - No basis for this derogation. - Case-control studies are a logical extension of cohort studies and an efficient way to learn about associations.

starts with disease than exposure

Anxiety and Depression: Anxiety: consequence of extreme arousal - Anxiety is an overestimation of _____- - Threat could be of any kind

threat

Cross-Sectional Studies: (walmart/mall studies) Both risk factors and the presence or absence of disease are measured at the same point in time - Sometimes called prevalence studies - Relatively inexpensive - Does not allow determination of the temporal relationship between a potential cause and effect

typically uses a survey and measures 1 point in time. not helpful determining causation

Analysis of Cohort Studies: • Basic analysis involves calculation of incidence of disease among exposed and unexposed groups. • Depending on available data, you can calculate cumulative incidence or incidence rates. • Set up of 2 x 2 tables.

uses cumulative incidence or incidence rates

MI: Epi studies combined with laboratorty study identify risk factors ◦ Cigarette smoking ◦ Cholesterol ◦ HTN ◦ Stress ◦ Family history ◦ Obesity ◦ Physical Activity Which of the above contribute the most risk? What are the relationships between risk factors?

• The issue of causation is not as simple as it first appears • Thus, the need for a unifying concept of causation

Hill's Criteria of Causality

1) strength of association- relationship between casual factor and disease outcome 2) consistency of finding- associations are repeated 3) specificity of association- very specific cause 4) temporality- cause must be before the effect 5) biological gradient- dose and response relationship, more exposure causes higher risk 6) biologic or theoretical plausality- has to make biological sense 7) coherence with the established knowledge- established knowledge should not conflict with findings 8) experiment- manipulation of the presumed cause should result in lower rate of disease 9)analogy- weaker evidence may be accepted as causal, if similar factors have already been accepted as a cause of the disease

CANCER: RISK FACTORS: • Genetic predisposition - Hereditary Cancer Syndromes - Mutated genes passed from parent to child - 5-10% of all cancers • _____ - #1 risk factor • Health Behaviors - *most studies are observational, findings should be interpreted with caution. - Alcohol - Tobacco - Diet - Obesity - Physical Inactivity • Exposure to some environmental factor - Sunlight - Secondhand smoke - Other carcinogens - Viruses, Pesticides, Asbestos, Radon, Arsenic,

Age

PARAMOUNT STUDIES: AEROBIC EXERCISE VERSUS DRUG THERAPY FOR PANIC DISORDER AND AGORAPHOBIA: Randomized clinical trail showed that 10 weeks of aerobic exercise training was effective in reducing symptoms of anxiety among patients with anxiety disorder but not as effective as ____

drug therapy

Crude, Specific, and Standardized Rates: • ______: based on a total population without consideration of any of the population characteristics (doesn't take influencing variables into account) • _____: calculated separately for population subgroups (divide data by age categories) • ______: have been standardized (adjusted) for some population characteristic

Crude Specific Standardized

DEPRESSION AND ANXIETY and physical activity: DEFINITIONS: - Major _____-: One of two major categories of mood disorders (the other being manic-depressive disorder) characterized by depressed mood or loss of interest or pleasure and other behavioral and psychological symptoms - _____-: A response to a perceived threat that consist of feelings of tension, apprehension, and nervousness; unpleasant thoughts or worries; and physiological changes - ______ anxiety: feelings of anxiety are temporary and fluctuate from moment to moment - ______- anxiety: feelings are constant and persistent - Anxiety ______: illnesses that cause people to feel frightened, distressed, and uneasy for extended periods of time for no apparent reason. Left untreated, these disorders can reduce productivity and diminish the quality of life.

Depression Anxiety State Trait disorders

Census of U.S. Population: • Complete count of population taken every ten years • Some miscounting occurs • Also obtains information on demographic characteristics • Provides key information on denominators for risks and rates

Now the biggest data source is the census which supposedly is a complete count of the population. Do any of you remember completing the 2010 census? This was 3 different surveys you could have received...some had in home interviews. Most of you all probably filled out the one pager. But a lot of people get missed. Questions can very but can ask you such things as how many TVs do you have in your house, if you were married, how many people in your house. It provides us with the denominators for our data...and you can get this information down to the block level...or by state, counties, cities. Certain universities can get this information directly from the census and so they can have it for research purposes. A lot is also directly avaliable online.

Data Sources/ Surveillance of Physical Activity: • Endemic - The habitual presence (or usual occurrence) of a disease within a given geographic area • Epidemic - Occurrence of a disease that has a greater than expected frequency in a population during a specific period of time • Pandemic - An epidemic that spreads widely across a region or the world

Endemic refers to a disease or the level of a disease which is present in a population or area all of the time, not as an exception to the rule. The endemic level is the baseline level of disease which is normal, although it may still not be the desirable level. Outbreak - Refers to the number of cases (disease) that exceeds what would be expected Endemic - An infection within a geographic location that is existing perpetually Pandemic - A global endemic Epidemic: An outbreak of disease that attacks many peoples at about the same time and may spread through one or several communities. Pandemic: When an epidemic spreads throughout the world. On Friday, he said the WHO hadn't declared a pandemic in part because most cases of COVID-19 were still traced to known contacts or clusters of cases, and there wasn't any "evidence as yet that the virus is spreading freely in communities."

Important Issues in Experimental Studies: Ethical Considerations: • ______: Must be genuine doubt about efficacy of treatment yet sufficient belief that it may work • ______: What if it becomes apparent, before the trial is over, that the new treatment is beneficial (and should not be withheld from the placebo group) or is toxic (and treatment should be withdrawn)?

Equipoise Stopping rules

Other Major Sources of Descriptive Public Health Data: • National Health and Nutrition Examination Survey - Gathers information on health and diet of US population. Includes interviews and health tests • Behavioral Risk Factor Surveillance System - Telephone survey on health risk behaviors related to chronic disease, injuries and death. Incudes use of screening and preventive services, smoking, alcohol use, physical activities, fruit and vegetable consumption, seatbelt use, and weight control

Have this on Hispanics as well (National Health and Nutrion)...also Youth Risk Factor

Vital Statistics: • Data on births, deaths, marriages, divorces, fetal deaths • Birth and death information is considered virtually complete in US • Public health data on birth certificate includes birth weight and gestational age • Death certificates have information on the cause of death and underlying conditions • Death information has been computerized at a national level since 1976

Now with death certificates the information listed is not always accurate because they are afraid what the ramifications of the family might be. For example, rural counties might avoid putting "suicide" down for what it might imply, or other places might not want to put "drug overdose"...they don't want people knowing this. All this information is now computerized so if you have someone social security number, you can see if they have died or not.

Considerations When Interpreting These Data: • Know the specific population that is covered by the data collection system. • Understand the calendar period covered by the data collection system and the frequency with which data are updated. The most current available data typically lags a year or two behind the present. • Every data collection system has some incomplete and inaccurate material.

Need to know who was included, what time period this is for. There are lots of sources of data besides collecting it on your own and you just need to weigh the balance between what you are trying to find out, and can you really answer the question....given all the negatives associated with it. For example what are the advantages and disadvantages to collecting data on your own verus using another source?

ETIOLOGY OF ANXIETY DISORDERS: Neurotransmitters are the brain's communication system. They cause one nerve (neuron) to communicate with another, telling it what to do. Anxiety is created by imbalances, or improper amounts of neurotransmitters. - _____ is associated with anxiety and is known for its impact on mood, appetite, and sleep - People with anxiety disorders have decreased levels of ____ ____, (gamma-aminobutyric acid) is linked to anxiety - People who experience chronic anxiety may have a GABA deficiency - Body is already in a heightened state of arousal and vigilance, thus producing a biological vulnerability to increased levels of stress

Serotonin serotonin GABA

Other Major Sources of Descriptive Public Health Data: • World Health Statistics Annual - Compiles international morbidity and mortality data on WHO member states • Cancer Incidence on Five Continents - WHO International Agency for Research on Cancer (IARC) collects data on cancer incidence and mortality from many countries around the world

WHO also combines annual statistics. What determines the best data you can get? Are these sources the best or should you collect your own data? All depends on your question. And other things like accessibility, funding, how much it costs to get the data, and participant burden, and investigator burden

ETIOLOGY OF DEPRESSION: Depression is associated with imbalances in neurotransmitters - Chemicals that influence the activity of brain cells that regulate mood, pleasure, and rational thought 3 Principles Proposed by Eric Kandel (1998) 1. Actions at the ______ are responsible for all mental and psychological processes 2. Brain functioning is controlled by _____ 3. ______, ______, _______ factors can produce alterations in gene expression 4. Alterations in gene expression induce ______ in brain functioning 5. Treatments for mental illness exert their effect by producing alterations in _________, resulting in beneficial changes in brain function

brain level genes Social, development, and environmental changes gene expression

PARAMOUNT STUDIES: US NATIONAL COMORBIDITY STUDY": - Nationally representative sample of adults ages 15 to 54 in US (n=5877) - People who said they regularly got physical exercise for recreation or at work had 25% lower odds of being diagnosed with major depression during the past year (OR=0.75; 95% CI: 0.6-0.94) - There was a ______ in the odds of major depression, dysthymia, and bipolar disorder with higher frequency of PA

dose-response reduction

Selection of Comparison (Unexposed) Group: • Principle: You want the comparison (unexposed) group to be as similar as possible to the exposed group with respect to all other factors except the exposure. • If the exposure has no effect on disease occurrence, then the rate of disease in the exposed and comparison groups will be the same.

cant randomized cohort bc its an observational study. they do exposed and unexposed groups

Example: Aerobics Center Longitudinal Study (ACLS): • Measured physical fitness, assessed by maximal treadmill testing in 4,820 men and 1219 women aged 20 to 65 years. Participants had no history of cardiovascular disease and were normotensive at baseline. • Exposed group: People who had low levels of fitness according to their time to reach exhaustion during the treadmill test (72% of group) • Unexposed group: People who had high levels of fitness according to their time to reach exhaustion during the treadmill test • Outcomes of interest: high blood pressure (140/90 mHg), all-cause mortality, CVD, cancer, and other cardiovascular health factors • Principle: If physical fitness is not associated with the outcomes under study, then the outcome rates will be the same in both groups

cohorts allow you to look at all other outcomes and looking at rare exposures

Timing of cohort studies: • Retrospective: both exposure and disease have occurred at start of study Exposure------------------------> Disease ( *Study starts) *Study starts • • Prospective: exposure has (probably) occurred, disease has not occurred Exposure----------------------> Disease *Study starts @ exposure •Ambi-directional: elements of both

cohorts starts with exposure and then disease

Opioid Systems: - Abnormal levels of ______ have been discovered in individuals with depression and anxiety - Mood elevations and reduced anxiety following acute exercise is due to the release and binding of _____ (endogenous opioids) to their receptor sites in the brain - PA increases endogenous opioid activity in the nervous system and may induce a ____-state and reduce pain u

endorphins B-endorphins euphoric

Risk Difference (continued): • Purpose: Gives information on - the absolute effect of _____ on disease occurrence. - the excess ______ in the exposed group compared to the unexposed group. - the public health ______ of an exposure, that is, how much disease would be prevented if the exposure were removed. This assumes that the exposure causes the disease.

exposure disease risk impact

Cancer in Physical Activity epidemiology: CANCER: ETIOLOGY: Uncontrolled growth of abnormal cells - Cancer IS a ____ disease Triggered by mutations of the signals that control cell division - No Contact Inhibition, Failed Apoptosis Lead to development of a neoplasm (tumor) - Benign - non-harming - Invasive - invade and destroy normal tissue _____ cancer cells spread to other parts of the body Constant mutation and metastasis make cancer so difficult to treat Cancers may cause death directly or indirectly - ____- - Invasion of vital organs - ______ - Failure of bodily function due to fatigue à higher risk for comorbidity

genetic Metastasized Directly Indirectly

Neurogenesis: New neuronal growth in the adult brain, particularly in the _____, has been implicated in the treatment of psychiatric conditions including depression and anxiety PA may up regulate _____ neurogenesis - Influences B-endorphins, vascular endothelial growth, and serotonin

hippocampus hippocampal

hypothalamus- pituitary gland-

hypothalamus controls release of hormones to pituitary gland pituitary gland releases hormones into the bloodstream. the hormones travel to kidneys. adrenal glands are on top and releases hormone response flight or fight

Serotonin Levels: improves mood Neurotransmitter PA _____- serotonin levels in the brain

increases *ppl w/ an anxiety they will have reduce serotonin levels. this is shown by animal studies where they get shocked

STATISTICS AND RECENT TRENDS: - 8% of _____ and 4% of _____ have some form of clinical depression at any point in time - The annual prevalence of major depression in the United States has increased steadily during the past 50 years - Anxiety disorders are the most common mental illnesses in the US, affecting about 23 million people (4% of ____- and 2% of _____) each year. - Generalized anxiety disorder is a common disorder with a lifetime prevalence of ____- in the general population . Onset of GAD symptoms usually occurs during an individuals early 20s and is often chronic, lasting more than 5 years.

women, men women, men 4-7%

Confidence Intervals: • One definition of a confidence interval: Range within which the true magnitude of effect lies with a stated probability, or a certain degree of assurance (usually 95%) • The strict statistical definition: If you did the study 100 times and got 100 point estimates and 100 CIs, in 95 of the 100 results, the true point estimate would lie within the given interval. In 5 instances, the true point estimate would not lie within the given interval. • Note that the point estimate is RR, OR, or RD • Another way to think of a confidence interval: A range of possible values for the measure of association that are compatible with the observed data within specified limits (usually 95%) • Width of confidence interval indicates amount of sampling variability in the data. Width is determined by variability in the data and an arbitrary "certainty factor" (usually 95%, but you can choose any % you want) • The CI tells you much more than the P value: the range of hypotheses that are compatible with the data.

• EX: Pesticides and breast cancer • RR = 1.4 95% CI = 0.7 - 2.6 •Again, the results indicate that the best estimate of the increased breast cancer risk associated with pesticide exposure is 1.4. However, we are 95% confident that the true RR lies between 0.7 and 2.6. That is, the data are also consistent with hypotheses of 0.7 to 2.6.