The approach to medicine that is concerned with the health of the community as a whole

the prevention of injury and disease.

aims to monitor and diagnose the health concerns of entire communities and promote healthy practices and behaviors to assure populations stay healthy.

The individual's health status over a lifetime.

Expands from total health to death.

• Genetic makeup
• Demographic characteristics
• Environmental factors
• Nutritional history
• Social environment
• Behavior
• AGE!

The public health continuum covers what 3 aspects?

Which do optometrists play a bigger role in?

Total Health, Subclinical disease, and Clinical Horizon

Subclinical Disesase and Clinical Horizon

What is primary prevention?

main way to provide this?

Measures taken to prevent a disesase process from getting started

(ex. safety glasses to prevent eye injuries)

cheapest method of prevention

main way to provide this - educate patients.

What is the goal of secondary prevention?

Who performs this typically?

What are these services aimed at?

to stop the subclinical disease before it becomes symptomatic or before it can be transmitted to others.

mostly performed by healthcare practitioners.

these services are aimed at early detection.

(ex. screening for eye problems in children to establish early treatment)

What is tertiary prevention?

What effect does this have on the condition?

Specifically providing patients with what?

Rehabilitative or palliative clinical treatment given when a disease of condition has become disabling.

Does NOT cure the disease.

May slow the natural course of some progressive diseases, and prevent or delay many of the complications associatted with chronic diseases.

Providing patients ways to deal with and manage.

The 8 Public Health Disciplines..

(don't memorize, just know what they are)

Examples given..

1. Health Policy and Management (Ex. Development of mandatory eye exam program in Kentucky)
2. Epidemiology (ex. CLEERE Study of prevalence of refractive error in children)
3. Behavioral Science and Health Education (ex. LALES Study of noncompliance with Vision Care Guidelines in Latinos with Type 2 Diabetes Mellitus)
   
4. Occupational Safety (ex. Prevention of eye injuries among construction workers)
   
5. Environmental Health Sciences (ex. Lead-induced health problems)
6. Global Health (ex. Prevention of onchocerciasis in Tanzania and other countries of tropical climate)
7. Maternal and child Health (ex. Retinopathy of Prematurity caused by Oxygen exposure at birth)
8. Specific Areas (ex. Oral, Pharm, Infectious, etc.)

What is the main reason we need to know about public health?

generally?

so we can make informed decisions for treatment.

so that we may better serve the public in general concerning: disease prevalence, probably outcomes, and behavior.

1. Disease prevalence
2. Probable outcomes
3. Behavior

What is epidemiology?

What does it involve?

The study of distribution and determinants of disease

Involves: Basic Sciences, Clinical practive, and population data.

Who is the father of epidemiology?

What did he do?

John Snow

looked at different factors such as age, SES, and sex for the affected patients.

Biblical times - large #'s of death were documented, they may not have understood the reasons

Bubonic plague - 1400's, 25-50% of the population died. The health of the individuals was assumed to be influenced by humors (Earth, Air, Water, and Fire)

Beginning of "infectious" ideas - docters were concerned about the infected airs and they would recommend masks to avoid breathing in the "bad airs". Treatment may include bleeding the bad airs out of a person.

Yellow Fever epidemic - 1700's, Philadelphia, a study showed that patients being bled had a higher rate of mortality than those not treated at all (STARTED DOING STUDIES!!)

Cholera epidemic - 1850's, London, John Snow (father of epidemiology) looked at different factors such as age, SES, and sex for the affected patients.

rate-frequency of events that occur in a defined period of time divided by the population at risk

Mortality Rate = #    People dying      x Unit Time

# of people in group

1. Research Evidence
2. Clinical Expertise
3. Patient Values

Practice is based on "art" and science

evidence-based practice

scientifically based

must validate a teachers' advice: Investigation, Literature search, Cross referencing.

Cannot just assume that because two things happened to the same person, one caused the other!

Even with evidence, may only be able to conclude that an exposure may increase the risk of a disease, vs saying that it causes it

Sufficient cause

What is cause and effect?

what are the 5 aspects?

To make causal inference, need to evaluate.

1. Strength of association

2. Biological plausibilitu

3. Agreement with Accepted Knowledge

4. Time sequence

5. Dose response

The degree to which one variable is related to another.

Sufficient evidence or ...

Bias? Confounding factors? Recruitment and measurement done? possibility of two things hapenning at the same time due to chance alone?

see how much two variables hace in common..

Relative Risk

Correlation coefficient

Regression coefficient

Differences between groups (means and others)

increase in exposure leads to an increase in the severity of the disease

may have a threshold dose-response relationship

does not always apply, but most times..

What is bias?

What are the 3 types?

Must rule out before making a causal inference.

1. Selection bias
2. Confounding bias
3. Information bias

A problem in recruitment

When selection bias happens, the subjects are not representative of the target population

Can severly affect the validity of a study. Once selection bias is present, NOTHING can be done to fix the study

best to design the study using "random sampling methods" (ex. zip codes)

however, these are expensive so a lot of studies use "convenience sampling methods" (ex. clinic patients)

What is confounding bias?

How to control it?

can be created by a "confounder" or a variable that is associated with BOTH the exposure and the disease (ex. birth weight is a confounder for oxygen therapy, exposure, and ROP, disease)

Need to "control" for cofounders during the design or during data analysis

What are the two type of information bias?

How to control it?

1. Differential misclassification - usually due to use of different measuring toosl or due to examiner not being masked.

2. Non differential misclassification - due to lack of precision. ALWAYS PRESENT. Biases towards the null hypothesis (makes you think there was NO relationship).

CONTROL during design.

A valid study...

uses what kinda of sample?

measures what?

assesses and controls for what?

and reports the rold of what?

A sample the reflects the population at interest

Measures the varialbes of interest accurately

assesses and controls for bias

reports the role of chance

states the facts of what the researcher did. contains the information necessary to evaluate the validity of the study.

must have enough detail so that a reader can evaluate the validity and potentially replicate the experiment

includes something about informed consent and IRB (institutional review board)

3 parts: subjects, equipment, and procedures.

• Summarize
• Describe
• Compare
• Interpret
• Data Sets

Descriptive Epidemiology characterizes what?

What are the 3 aspects?

characterizes the distribution in a population.

3 aspects: person, place, time.

• age (most important determinant)
• sex
• race/ethnicity
• marital status
• religion
• occupation (stress, environment)

• World-wide
• Regional
• Local
• Urban vs Rural

• Short term
• Recurrent/periodical/seasonal
• long term

1. nominal
2. ordinal
3. continuous

Values that are categorical and there is NO order associated with them

(ex. male & female; white, African America, & Hispanic)

Values are categorical, but there IS an order associated with them

(ex. A, B, C, F; 1, 2, 3, 4-for grading angles; Mild, moderate, severe)

Values that are continuous (decimals, fractions) and there IS an order associated with them

(ex. Hemoglobin AiC: 6.3, 7.8)

used to make inferences about a population based on information obtained from samples

about a data set.

What is a sample?

Why is it selected?

Why must the sample be chosen carefully?

A subset of a population

Selected becayse in most cases is it impossible to test the enire population.

Must be chosen carefully to truly reflect the population is it intended to.

Describe the average of the distribution of values.

1. Mean
2. Median
3. Mode

The sum of all values divided by the # of values

outliers can skew the mean in one direction

The middle value when the values are organized in order

Outliers do not affect the median much.

the most common value

a set of data may or may not have a mode

The mean is preferred for normally-distributesd samples

The median is preferred for data sets with high variability (large standard deviation)

The mode is not used much but may be mentioned in some studies.

When comparing two groups, it's important to compare "means to means" and "medians to medians"

what are Measures of Variability?

what 4 are they?

Summarize how much the values differ from the average

1. range
2. standard deviation
3. variance
4. confidence intervals

The difference between the lowest value and the largest value in a sample.

Useful for finding out where values may lie.

The average of the deviation of all values from the mean.

In a bell-shaped curve:

The mean +/- 1 SD = 68% of the values

The mean +/- 2 SD = 95% of the values

The mean +/- 3 SD = 98% of the values

Standard Deviation squared.

Not often used in descriptive statistics

Most powerful measures of variability for normally distributed (parametric) data.

Contain the mean and the variability in one measure.

Most often used are 95% CI.

Expressed as P (low range, high range)

1. Heart disease
2. Cancer
3. Stroke (cerebrovascular diseases)
4. Chronic lower respiratory diseases
5. Accidents (unintentional injuries)
6. Alzheimer's disease
7. Diabetes
8. Influenza and Pneumonia

1. Smoking
2. Overweight
3. Diabetes
4. High Blood Pressure
5. Risky Behaviors (alcohol and drug use, promiscuity)

1. Coronary heart disease
2. Lower respiratory infections
3. HIV/AIDS
4. Perinatal conditions
5. Stroke (but don't typically live long enough)

What constitutes visually impaired?

is unequally distributed across age groups.

more than 82% of all people who are blind are 50 years of age and older, although they represent only 19% of the world's population

due to the expected number of years lived in blindness (bling years), childhood blindness remains a significant problem, with an estimated 1.4 million blind children below age 15.

visual impairment is not distributed uniformly throughout the world. more than 90% of the world's visually impaired live in developing countries

comparisons among countries are difficult due to different examination techniques and different data gathering capabilities.

third leading cause of blindness globally?

diabetes, smoking, steroid, and dietary factors, but no cause-effect relationship established.

high altitude = higher prevalence

countries with higher number of black inhabitants have a higher prevalence of POAG

diabetes = higer prevalence, or higher detection rates (more eye exams?)

what is the leading cause of permanent impairment of central vision

1. perinatal (ROP)
2. genetic (albinism)
3. traumatic

1. xerophthalmia
2. onchocerciasis
3. measles
4. trachoma

half