WEEK 2 (Chapter 2 +3)

Question 1

What are the key measures of health and disease?

Answer 1

pop size, birth and death rate, causes of death, freq and causes of disease and disability and rate at which ppl engage in risky behaviors

Question 2

What is demography?

Answer 2

is the study of size and composition of populations

Question 3

How are vital statistics collected?

Answer 3

Most countries maintain vital stats of their residents collected from birth and death certificates, marriage, & divorce certificates and from census records

Question 4

How do you measure birth rate? Death rate?

Answer 4

• Birth rate is annual number of births per 1000 people in the total population

death rate (or mortality rate) is annual # of deaths per 1000

Question 5

What is the age-adjusted rate? (of death?)

Answer 5

age-adjusted rate accounts for differences in the age structures of populations

Death rte usually higher with a large % of older adults than in populations w lots of children so this is way of accounting for this

Question 6

Measuring mortality- challenging for 2 reasons.

Answer 6

1: many parts of world no system for stats. Places where deaths occur in homes instead of hospitals, few births and deaths are documented by gov’t officials.
- -> Diadv’t pop less likely to document deaths. Low-income countries, less data
2: assigning one cause of death to each individual. Lots of co-morbidities.

Question 7

Given the 2 limitations to keeping stats on mortality, are epidemiologists able to make reasonably accurate estimations?

Answer 7

Yes, using standardized estimation methods and the best available data, can make reasonably accurate assessments of annual deaths, cause of death by age and group and sex in every region of the world

Question 8

Life expectancy at birth =

Answer 8

• the median expected age at death of all babies born alive

Question 9

Healthy life expectancy is

Answer 9

he # of years the average individual born into the population can expect to live without disability.

Question 10

What is the effect of high infant mortality on median age of death?

Answer 10

Places with high infant mortality put the median age at death in middle adulthood

Question 11

What is morbidity?

Answer 11

refers to the presence of illness or disease, whether mild (cold) or severe

Question 12

Two terms to describe morbidity rate for a particular disease in a population are

Answer 12

• incidence and prevalence

Question 13

What is incidence and what is it best for describing?

Answer 13

o is the number of new cases of the disease occurring in a time period dicded by the total number of people at risk for that disease.

Describes infectious diseases, acute diseases and outbreaks

Question 14

What is prevalence and what is it best for describing?

Answer 14

o is the number of total existing diseases, both newly diagnosed cases and cases diagnosed in the past, divided by total pop. Usually describes the amunt of chronic disease in a population

Question 15

What are Quality-adjusted life years (QALY’S):

Answer 15

number and quality of years lived increased if interventions decerase the prevelance or incidence of diseases (ie. vaccines)

Question 16

T/F
While there are considerable differences in life expectancy at birth between various country and dworld regions, the lie expect o people who have survived to adulthood is relatively similar across nations

Answer 16

T - a person who lives until 50 can usually expect to life into 70s. If live until 70, likely to live to 80.

Question 17

What is a case definition?

Answer 17

• Health researchers measuring the burden of disease in a population must have a clear case definition that spells out exactly what char indicate that a person has the disease and must specify a well-defined pop of interest especially if tracking

Question 18

disability-adjusted life year (DALY)

Answer 18

a way of estimating the burden of disease in a population by combining the burden from premature death, mreasured as years of life lost (YLLs), plus the burden from disability, measured as years of life with disability (YLD)

• Diseases that kill children that could have survived result in many YLLS and YLD

Question 19

Main pro and con of DALYs?

Answer 19

• Benefit of DALY is that it highlights the high burden of disability caused by mental health disorders.
• Difficult to assign an accurate weight to the decrease in quality of life caused by various things bc depends so much on the individual (depends on circumstance of the person)

Question 20

How serious is the effect of non-modifiable risk factors in terms of causing disease?

Answer 20

• Modifiable risk factors thought to be responsible for at least 2/3 of all worldwide deaths from noncommunicavle diseases like heart disease, stroke, diabetes, cancer, anc chronic lung disease

Question 21

3 main classifications for causes of death and disability

Answer 21

1) communicable (infectious) diseases (often grouped with preg-related conditions, nutritional deficiencies + disease of newborns), 2) noncommunicable conditions (including mental health) and 3) injuries.

Question 22

What is often grouped with infectious diseases?

Answer 22

Those ocnditions that primarily affect low income households:

Perinatal conditions (disease of neborns such as primaturity), maternal conditions, and nutritional deficiencies

Question 23

What is the difference between genotype and phenotype?

Answer 23

Genotype is the version of a gene a person carries and a phenotype is the way a char that results from having a particular allele or a version of a gene, is expressed – perhaps in a physical appearance, the way a person develops or functions

Question 24

Causes of NCD’s?

Answer 24

o Result from a variety of Etiologies such as inflm, autoimmune.
o Some are genetic
o Some conditions are caused by extra chromosome or missing part of one
o Some conditions caused by genetic mutations, perm changes in the seq of bases that make up DNA that occur after birth
o Causes of NCD often not clear but linked to risk factors

Question 25

What is the leading cause of death of adults in every part of the world?

Answer 25

NCDs

Question 26

What are Neuropsychiatric Disorders? Why is it difficult to assess the impact of these on pop health and disability?

Answer 26

o Includes mental illness as well as developmental disorders, autusm, neurological disorders (such as Parkinson’s, MS, etc.), seizure disorders such as epilepsy and dementia, anxiety, mood disorders

o Challenge to assessing is diagnosis depends on culture and many disorders exist as part of a spectrum where distinction is classified as ‘noral’ or disorder is blurry. Many undiagnosed

Question 27

Worldwide, what % of deaths d/t to injury are intensional and unintentional?

Answer 27

o About 2/3 of injury deaths worldwide each year are from unintentional injuries and 1/3 are intentional injuries

Question 28

What increases risk to injury?

Answer 28

Poverty

Question 29

Three of the best sources for basic disease info

Answer 29

• WHO. The US centers for disease control and prevention (CDC), and the US national instutitues of health (NIH).

Question 30

What are secondary sources (3 examples?)

Is this the best place for this info?

Answer 30

Fact sheets, annual reports and other summaries of research findings

• Best way to get access if primary srouces such as original research reports and journals

Question 31

Goals of public health research include

Answer 31

• identifying classifying new health problems, determining risk factors for disease, developing and testing new interventions for preventing or treating illness, evaluating the impact of health policies on health outcomes, and synthesizing existing knowledge

Question 32

Epidemiology is

Answer 32

the study of distribution and determinants of morbidity, mortality and disability in populations
- collect + disseminate data about the ehatlh-related conditions that occur in particular populations and the characteristics of the people who are most at risk fo devleoping those conditions

Question 33

How is epidemiology helpful for communities

Answer 33

• Helps communicate to set their own public health priorities and design and evaluate programs to address these issues, especially when a process called community-based participatory research (CBPR) is used.

Question 34

How is epidemiology helpful for clinicians?

Answer 34

• Information helps clinicians diagnose illness, prescribe appropriate therapies and encourage healthy lifestyles for their patients

Question 35

By what means is data collected for most primary studies?

Answer 35

• Most primary studes are observational or asking questions via questionnaire.

Can also be experimental

Question 36

Secondary vs teritiary study?

Answer 36

• A secondary study also contributes to th body of knowledge o a topic by analyzing and reporting on existing data that someone else collected
• A tertiary study seeks to identify all the primary (and secondary) studies that have been published on a particular topic and to summarize what those studies say (these are systematic reviews + meta=analysis)

Question 37

What are observational study designs?

Answer 37

• Observational study simply observes what people are doing or asks what they have done in the past
• No intervention for participants

Question 38

2 kinds of observational study designs?

Answer 38

• Descriptive studies

* Analytic studies

Question 39

What are descirptive studies?

Answer 39

seek to describe the members of a population the prevalence of risk factors within that population, or the rate of disease within that population. Often seek to answer questions about person, palce, and time. (who, what, when?)

Question 40

Analytic studies?

Answer 40

aim to understand the associations between risk factors and disease within a population and to answer “why” questions.

Question 41

Prevalence survey
AKA?
What is it?

Answer 41

• also called a cross-sectional survey can be used to get a snapshot of populations health status at one point in time
• Basically recruit a sample, ask questions, analyze the data
• Questionnaire can cover a wide variety of topic such as demographics, risk behaviours, income, illness, etc.

Question 42

In prevalence surveys, can use KAP survey instrument. What does this mean?

Answer 42

questions about knowledge, attitudes/beliefs, and practices/behaviours

Question 43

2 key cautions about conducting and critically assessing cross-sectional surveys

Answer 43

1) important for prevalence studies to recreuit ppl who are truly representative of the population the researchers say they want to examine.
2) no conclusions about causality can be made from cross sectional data, because all the questions about exposure and diseases are asked at the same time.

Question 44

Case study vs case series

Answer 44

• a case series looks at the characteristic of a group of people who all have the same disease
• a case study is a description of one patient

Question 45

What is the purpose of a case series?

Answer 45

• the goal of a case series may be to understand the demographic and other characteristics of people with a particular disease, to describe an unusual presentation of a disease or to clarify the typical progession of a disease

• usually done for and by clinicians, and summarize the people treated with a disease at a particular hospital

Question 46

Is it possible to examine risk factors for a disease in a case series?

Answer 46

No because no comparison group is used

Question 47

What are case control studies?

Answer 47

• recruit people with a disease (causes) and similar people who do not have that disease (controls) so that their past exposures can be compared.
• Asked about health beahviours, env’t exposures and health hx

Question 48

What is the ideal strategy for learning about rare diseases?

Why do these need to be interoreted carefully?

Answer 48

Case control studies

Can be helpful for identifying risk factors but must be interpreted cautiously bc participants may have difficulty recalling exposures

Question 49

Common way too look at the association between an exposure and a disease outcome is…

Answer 49

to create a 2 x 2 table that has two rows for exposure status and 2 columns for disease status..
Each individual in the study population is classified into one of the 4 groups created by the 2 x 2 table- exposed and diseased, exposed but not diseased, etc.

Question 50

Typical measure of association between an exposure and an outocme in a case control study:

Answer 50

Odds ratio

Question 51

What is the odds ratio (OR)?

Answer 51

compares the odds of a case having a hx of a particular exposure to the odds of a control having been exposed to the portential risk factor.

Question 52

How to interpret an odds ratio?

Answer 52

• An OR near 1 means that there was no association bet exposure and disease
• OR >1 means ppl with disease are more likely than ppl without disease to have hx of exposure
• OR <1 cases were less likely than controls to have a hx of the exposure, implies that the exposure was protective

Question 53

Because a relatively small number of people sampled from a larger pop cannot exactly describe the pop as a whole, ORs and others statistical measures are ofetn reported using _____

Answer 53

Confidence Intervals

Question 54

What does a 95% confidence interval for an OR mean?

Answer 54

• A 95% confidence interval for an OR can be interpreted as saying “based on the sample of ppl the researchers took from the larger pop, we can be 95% confident that the true OR in the pop as a whole is somewhere within this range of possible OR.

Question 55

Is the result said to be statistically significant if the confidence interval is >1, <1 or overlapping 1?
(I don’t get it…see p. 47)

Answer 55

• If entire confidence interfval is >1 the result is said to be stat significant and the conclusion is that the exposure appears to be risky. And >1 then the exposure is protective.
• If confidence interval overlaps 1 than no strong evidence of risky or protective exposure

Question 56

What are cohort studies?

Answer 56

• A cohort is a group of similar people and cohort studies recruit a group of similar eople and follow them forward in time.
• Asked about exposures beforehand and then tracked for months or years to see who develops the dx.

Question 57

T/F It is possible to explore causation with cohort studies

Answer 57

T - Useful for establishing if exposure causes disease and for measuring the incidence of new dx in a pop.

Question 58

• 2 of the most common measures of association for a cohort study are

Answer 58

the rate ratio and the attributable risk.

Question 59

What is the incidence rate ratio?

AKA?

Answer 59

(also called the risk ratio or relative risk, or RR) is calculated by dividing the rate of incident disease in the exposed cohort by the rate in the unexposed cohort.

Question 60

How to interpret a rate ratio?

Answer 60

• RR near 1 means that exposed and unexposed partcipatnets were equally likely to develop the disease during the study period
• An RR greater than 1 indicates that the exposure was associated w inc risk fo dx.
• RR less than 1 indicates exposure was protective.

Question 61

What is the rate difference?

AKA?

Answer 61

(also known as excess risk or attributable risk) subtracts the rate of disease in the unexposed from the rate of disease in the exposed
- If the exposed and unexposed pops were similar except for their exposure status, then this differnce in disease rates represents cases of disease among exposed people that would not have occurred tif they had not been exposed

Question 62

Try to understand example described at tope of page 50…

Answer 62

xx

Question 63

Experimental studies AKA?

Answer 63

Intervention studies

are studies in which the researchers assign participants to receive a particular exposure

Question 64

T/F Experimental studies are the best study design for assigning causation

Answer 64

T - but are ethical issues!

Question 65

What is an example of experimental studies in medicine/pharm?

Answer 65

CLinical trials of a new med or product

Question 66

What design do most clinical trials use?

Answer 66

• Most clinical trials use a randomized controlled trial (RCT) design in which ppl are assigned by chance either placebo or the drug
• Most clinical trials are double blind aka the partcipants and the ppl assessing them don’t know who has placebo and who has drug

Question 67

• Most common outcome measure for RCt is the _______ of the intervention

Answer 67

efficacy

Question 68

KEy points on research ethics

sorry, I think this is pretty obvious so i’m just going to let you read through!

Answer 68

• Nearly all health research projects that involve contact w people or access to identifiable personal ino are supervised by ethics committess commonly called institutional review boards (IRBs), or Research Ethics Committees (RECs)
• Study should be beneficial for both committees (beneficience) also nonmaleficience (study to do no harm)
• Respect for persons demands autonomy- volunteer to do study or are informed about study to help make decision
• Should be told about risks and benefits, informed consent should be done

Question 69

How does distributive justice play into research?

Answer 69

• Distributive justice aims to ensure that the populations that bear the risks fo research participation have access to the benefits of that research. Ie) med research, participants should have access to that medication after it is approved and marketed.

Question 70

What are correlational studies?

AKA?

Answer 70

• Sometimes called an ecological study uses numeric data about a particular exposure and health outcome from several populations to look for trends.
• Results often displayed using a scatterplot (x and y graph)

Question 71

What does the value of ‘r’, the correlation coefficient indicate?
Positive vs negative r?

Answer 71

• Value of the correlation coefficient, r measures how well the line predicts the location of the points.
• Slope of the line shows the direction of association
• A positive value for r indicates a positive slope and means inc in rate of exposure = inc rate of outcome
• Neg valuef or r indicates a neg slope and shoes an inc in the exposure rate = decrease in the outcome rate

Question 72

What does an ‘r’ of 1 mean? 0.5? 0?

Answer 72

An r near 1 means that all the points fall almost exactl on a line, so if the exposure level in a population is known, the outcome can be predicted with a high level of certainty
• An r near 0 is extremely weak and eans that the line has no predictive value
• R near 0.5 indicates a moderately strong correlation

Question 73

T/F Ecological (correlational) studies can be used to test individual-level correlations
What is the ecological fallacy?

Answer 73

F - Ecological studies are not used to test individual-level correlations

The ecological fallacy describes when population-level correlations are incorrectly interpreted to be measures of individual risk.

Question 74

What is publication bias?

Answer 74

• Publication bias occurs when studies that find a statistically significant results are more likely than “null result” studies to published

Question 75

How are mathematical models for forecasting diseases etc?

Answer 75

• Mathematical models can be used to estimate disease rates in pop lacking good data and to predict future health trends.
• Ie. global burden of disease studies generally start with a systematic review of the disease of interest and find incomplete data for many countries and a model will incorporate the info and estimate morbidity and mortality from other countries with similar geographic and socioeconomic profiles

Question 76

See pg 57 for discription of how to use confidence interval again…is complicated and I doubt we need to know it…

Answer 76

xx