HLTC19: Chronic Diseases (Midterm)

Question 1

what is a population?

Answer 1

a group of people with common characteristic(s)

_{eg. gender, age, occupation, etc.}

Question 2

focuses on the distribution of health-related states/events in specified populations

Answer 2

descriptive epidemiology

Question 3

quantifying how often a disease arises in a population

Answer 3

disease frequency

Question 4

quantifying disease frequency involves:

Answer 4

1. developing a definition of disease
2. instituting a mechanism for counting cases of disease w/in specified population
3. determining size of said population

Question 5

focuses on determinants of health-related states or events in specified populations

Answer 5

analytic epidemiology

Question 6

factors that bring about a change in a person’s health or makes a difference in a person’s health

Answer 6

disease determinants

Question 7

what are some goals and applications of epidemiology in relation to chronic diseases?

Answer 7

• control health problems
• determine extent of disease in a population
• identify patterns and trends in disease occurrence
• identify causes of disease
• evaluate effectiveness of measures that prevent and treat disease

Question 8

how does the WHO define chronic diseases?

Answer 8

chronic diseases are diseases of long duration with slow progression

Question 9

what are some common themes in defining chronic disease?

Answer 9

• share common risk factors
• begin slowly and develop gradually over time
• can occur at any age (but more common in adulthood)
• impact quality of life and limit daily activities
• require long-term management with multiple services required

Question 10

what are the 4 major chronic diseases?

Answer 10

1. CVD
2. Cancer
3. Chronic respiratory diseases
4. Diabetes

Question 11

what is the goal of public health?

Answer 11

to promote the health of the population through organized community efforts

Question 12

the state of complete physical, mental, and social well-being, not merely the absence of disease

Answer 12

health

Question 13

the study of pattern and causes of health-related outcomes and application of these findings to the improvement of public health

Answer 13

epidemiology

Question 14

a set of criteria that must be fulfilled to identify a person as representing a case of a particular disease

Answer 14

case definition

Question 15

a continuum b/w risk factors and disease as end result of continuum

Answer 15

chronic disease continuum

Question 16

overarching factors that are largely outside the control of the individual that have significant trickle down effects on other, more proximal determinants of public health

Answer 16

upstream determinants

Question 17

type of population where membership is defined at a point in time or an event, is permanent, and does not change

Answer 17

close/fixed population

_{eg. Japanese atomic bomb survivors}

Question 18

type of population where membership is defined on the basis of a changeable state or condition and is transient

Answer 18

open/dynamic population

_{eg. cancer registry (people added as they are diagnosed)}

Question 19

the shift from infectious and deficiency diseases to chronic, non-communicable diseases

Answer 19

epidemiological transition

Question 20

rate of occurrence of new cases of disease in a population at risk during a specified period of time

Answer 20

incidence

Question 21

frequency of current cases of disease (old + new) in a population at risk during a specified period of time

Answer 21

prevalence

Question 22

^{(proportion/rate)}

_____ tell us what fraction of the population is affected; _____ tell us how fast the disease is occurring

Answer 22

PROPORTIONS tell us what fraction of the population is affected; RATES tell us how fast the disease is occurring

Question 23

• # of new health-related events in a defined population within a specified period of time
• measures risk

Answer 23

incidence

Question 24

the fraction of people who experience the onset of the event during a specified time period

Answer 24

cumulative incidence / incidence proportion

(used when people are followed the entire time!!!)

vs. incidence rate when people are followed for a certain period of time/until disease occurs

Question 25

what is the formula for cumulative incidence?

Answer 25

Question 26

the rate at which new events occur in a population; takes into account variable time periods at risk

Answer 26

incidence density / incidence rate _{total amount of time EACH person was observed}

Question 27

what is the formula for incidence density / incidence rate?

Answer 27

Question 28

* the proportion of individuals in a population who have a disease or condition * measures **burden** of an event

Answer 28

prevalence

Question 29

what is the formula for prevalence?

Answer 29

Question 30

percentage of people in a population with the condition at a specific point in time

Answer 30

point prevalence

Question 31

percentage of people in a population with the condition over a specified period of time

Answer 31

period prevalence

Question 32

what are some factors that impact prevalence? * as incidence increases, prevalence \_\_\_\_\_ * as # of people cured increases, prevalence \_\_\_\_\_ * as # of people that survive increases, prevalence \_\_\_\_\_ * as more people die from disease, prevalence \_\_\_\_\_

Answer 32

* as incidence increases, prevalence **increases** * as # of people cured increases, prevalence **decreases** * as # of people that survive increases, prevalence **increases** * as more people die from disease, prevalence **decreases**

Question 33

an event/condition/characteristic that preceded disease onset and that, had the event/condition/characteristic been different, the disease would not have occurred at all or would not have occurred until some time later

Answer 33

cause

Question 34

measures public health impact of an exposure (difference in measures)

Answer 34

absolute measure of comparison

Question 35

measures strength of relationship of 2 factors (ratio of measures)

Answer 35

relative measure of comparison

Question 36

difference in rate of occurrence of disease due to exposure

Answer 36

risk/rate difference

Question 37

what is the formula for risk/rate difference?

Answer 37

RD = risk_exposed - risk_unexposed

Question 38

what does risk difference (RD) = 0 mean?

Answer 38

* risk in exposed = risk in unexposed * no increased risk attributed to exposure

Question 39

what does risk difference (RD) \> 0 mean?

Answer 39

* risk in exposed is greater than risk in non-exposed * excess risk attributed to exposure

Question 40

what does risk difference (RD) \< 0 mean?

Answer 40

* risk in exposed is less than risk in exposed * decreased risk attributed to exposure ("protective\*)

Question 41

risk of disease in exposed compared to risk of disease in unexposed

Answer 41

risk/rate ratio (RR) _{aka as relative risk}

Question 42

what is the formula for risk/rate ratio (relative risk)?

Answer 42

RR = R_exposed / R_unexposed

Question 43

what does it mean when relative risk (RR) = 1?

Answer 43

* risk in exposed is the same as risk in unexposed * there is no association b/w disease and exposure

Question 44

what does it mean when relative risk (RR) \> 1?

Answer 44

* risk in exposed is greater than risk in unexposed * there is a positive association b/w 2 factors

Question 45

what does it mean when relative risk (RR) \< 1?

Answer 45

* risk in exposed is lesser than risk in unexposed * there is a negative association b/w 2 factors

Question 46

what are the advantages and disadvantages of using an absolute measurement (ie. risk difference)?

Answer 46

**advantages:** * public health impact * absolute change measured **disadvantage:** * less commonly used

Question 47

what are the advantages and disadvantages of using a relative measurement (ie. relative risk)?

Answer 47

**advantages:** * can measure strength of association * commonly used **disadvantage:** * hard to interpret

Question 48

what is the 2-step process epidemiologists use when approaching causation?

Answer 48

1. assessing whether observation is valid or true 2. causal inference

Question 49

what are the essential attributes of true causes?

Answer 49

**association:** cause (X) must occur together with effect (Y) **time order:** cause must precede the effect (time periods can be short or long) **directionality:** asymmetrical relationship b/w cause and effect (want X to cause Y but don't want Y to cause X)

Question 50

focuses on the origins of the web of causation, including social, political, and economic determinants of health instead of individual-level determinants

Answer 50

ecosocial framework

Question 51

a complete causal mechanism that inevitably causes disease

Answer 51

sufficient cause

Question 52

each participating factor in a sufficient cause

Answer 52

component cause

Question 53

a causal component that it is a member of **every** sufficient cause

Answer 53

necessary cause

Question 54

what are the key attributes of a sufficient-component cause model?

Answer 54

* blocking action of one component stops completion of sufficient cause (just need to know one to prevent disease) * completion of sufficient cause leads to biological onset of disease * component causes may act far apart in time

Question 55

level of prevention that aims to prevent disease from occurring and reduce incidence

Answer 55

primary prevention

Question 56

level of prevention that delays onset and duration of clinical disease and aims to improve survival

Answer 56

secondary prevention

Question 57

level of prevention that slow disease progression and aims to improve survival

Answer 57

tertiary prevention

Question 58

why is a clear research question important?

Answer 58

formulating research questions precisely enables you to design a study with a good chance of answering them

Question 59

what is the **PICO** framework for research questions?

Answer 59

**Population:** sample of participants in study **Intervention:** treatment provided to participants **Comparison:** reference group used to compare with intervention **Outcome:** measure used to examine treatment effectiveness

Question 60

what is the **PECO** framework for research questions?

Answer 60

**P:** population of interest **E:** exposure level of participants **C:** reference group used to compare with exposure **O:** measure used to examine effects of exposure

Question 61

aims to collect **valid** and **precise** info about causes, prevention, and treatment of disease (to determine relationship b/w exposure and disease)

Answer 61

analytic epidemiological research

Question 62

experimental vs. observational studies: PICO or PECO?

Answer 62

* experimental studies follow **PICO framework** * observational studies follow **PECO framework/PO** (population outcome)

Question 63

what are the different directions for observational studies?

Answer 63

**cohort study:** when looking at exposure BEFORE outcome **case-control study:** when looking at exposure AFTER outcome (look at outcome first then exposure) **cross-sectional study:** when exposure and outcome are looked at at the same time

Question 64

when the investigator actively manipulates which groups receive the agent under study

Answer 64

experimental studies

Question 65

ensures that known and unknown potential confounders are equally distributed among groups and that they have similar baseline characteristics

Answer 65

randomization

Question 66

what are some advantages of RCTs?

Answer 66

* prospective * randomization * clear temporal sequence * strong evidence for causation

Question 67

what are some disadvantages of RCTs?

Answer 67

* contrived situation; might not reflect real world consequences * ethical restraints * human behaviour may be difficult to control * exclusions may limit generalizability * expensive to conduct

Question 68

when the investigator passively observes as nature takes its course

Answer 68

observational studies

Question 69

makes causal inferences about the association b/w exposure and disease

Answer 69

observational studies

Question 70

examines the relationship b/w exposure status and disease status at the same time for each subject

Answer 70

cross-sectional studies

Question 71

what are some advantages of cross-sectional studies?

Answer 71

* inexpensive * quick to conduct

Question 72

what are some disadvantages of cross-sectional studies?

Answer 72

* may exclude those with disease who died before study began * cannot establish temporality of relationship

Question 73

type of study that examines multiple health effects of an exposure

Answer 73

cohort studies

Question 74

when subjects are defined according to their exposure levels and followed for disease occurrence over time

Answer 74

cohort studies

Question 75

any designated group of persons who are followed or traced over a period of time

Answer 75

cohort

Question 76

a study where the cohort is assembled at present time and followed toward future (study initiated before outcomes occur)

Answer 76

prospective cohort study

Question 77

a study where the cohort is assembled in the past using existing records and is "followed" to present time (study initiated after outcomes occur)

Answer 77

retrospective/historical cohort study

Question 78

a combination of a prospective and retrospective cohort study

Answer 78

ambidirectional cohort study

Question 79

what are some similarities b/w cohort studies and RCTs?

Answer 79

* both can compare 2 or more exposure groups * both follow subjects to monitor outcomes * both can monitor more than one outcome * select groups for comparability

Question 80

what are the major differences in an RCT vs. a cohort study?

Answer 80

* researcher allocates exposure * randomization of exposure status to groups * can use placebo and masking/blinding

Question 81

* interval b/w action of exposure and disease onset * time required for a specific cause to produce an outcome

Answer 81

induction period _{eg. how long does it take for smoking to cause lung cancer?}

Question 82

* interval b/w disease onset and clinical diagnosis * the time b/w the disease's first presence and its recognition

Answer 82

latent period _{eg. how long after someone develops lung cancer do they start showing clinical symptoms?}

Question 83

what are some advantages of cohort studies?

Answer 83

* temporality established (exposure precedes outcome) * establishes incidence of disease * quality control measures can be implemented ^{_{(prospective)}} * inexpensive and fast to conduct ^{_{(retrospective)}}

Question 84

what are some disadvantages of cohort studies?

Answer 84

* expensive when outcome is rare or follow-up is long _{^{(prospective)}} * maintaining participation is difficult/loss to follow-up _{^{(prospective)}} * quality of data poor; rely only on available info _{^{(retrospective)}}

Question 85

where data is originally collected

Answer 85

data source

Question 86

when original data is collected for a specific purpose by or for an investigator

Answer 86

prospective data

Question 87

existing data that was recorded for another purpose

Answer 87

retrospective data (secondary use)

Question 88

captures demographic info on all individuals who received a HC # in Ontario (updates addresses)

Answer 88

Registered Persons Database (RPDB)

Question 89

arises from a systematic difference in the way that the exposure or outcome is measured b/w compared groups; results in different accuracy of info b/w comparison groups

Answer 89

information bias

Question 90

systematic differences b/w study groups in terms of accuracy or completeness of recall of past events

Answer 90

recall bias

Question 91

systematic difference in soliciting, recording, or interpreting info involving interviewers

Answer 91

interviewer/observer bias

Question 92

probability that test correctly classifies positive individuals who have pre-clinical disease

Answer 92

sensitivity

Question 93

probability that test correctly classifies individuals w/o pre-clinical disease as negative

Answer 93

specificity

Question 94

proportion of individuals with a positive test who have preclinical disease

Answer 94

positive predictor value (PPV) _{(↑ prevalence= ↑ PPV)}

Question 95

proportion of individuals w/o preclinical disease who test negative

Answer 95

negative predictor value (NPV) _{(↑ prevalence= ↓ NPV)}

Question 96

when a test has an extremely high **Sp**ecificity, a **P**ositive results tends to rule **in** the diagnosis

Answer 96

SpPin

Question 97

when a test has an extremely high **S**e**n**sitivity, a **N**egative result rules **out** the diagnosis

Answer 97

SnNout

Question 98

how to address information bias?

Answer 98

* comprehensive questions to improve recall and self-reporting (eg. close-ended questions) * standardized questionnaires, mask interviewer (if possible) * self-administered questions * validate data with another source

Question 99

* consistency b/w repeated measurement * repeatability or reproducibility of a test (get the same results everytime)

Answer 99

reliability

Question 100

the degree to which a variable represents what its intended to represent

Answer 100

validity

Question 101

* the degree to which study results are true for people being studied * validity of comparisons made w/in the study

Answer 101

internal validity

Question 102

* probability that observed result is due to chance * directly related to sample size * variability in data that can't be explained by the design or still remains after systematic error is eliminated

Answer 102

random error

Question 103

occurs when there is a systematic difference b/w individuals included in the study and individuals not included in the study (during selection and follow-up of participants)

Answer 103

selection bias

Question 104

* mixing of effects b/w exposure, outcome, and a 3rd variable (another exposure) * effects of the 2 exposure cannot be separated

Answer 104

confounding

Question 105

bias can affect the _____ of a study

Answer 105

bias can affect the **INTERNAL VALIDITY** of a study

Question 106

errors that results from procedures used to select subjects and from factors that influence participation in the study

Answer 106

selection bias

Question 107

* comes from selecting study subjects from a larger population * extent to which results are generalizable/applicable to another study population

Answer 107

external validity (generalizability)

Question 108

what are the major sources of information bias?

Answer 108

* recall bias * interviewer/observer bias

Question 109

what are the 3 key characteristics of confounders?

Answer 109

* must be associated with exposure * must be a risk factor for the outcome * must not be an intermediate step in the causal pathways b/w exposure and disease

Question 110

how can we control for confounding?

Answer 110

at the design stage: * randomization * restriction * matching at the analysis stage: * standardization * stratification * matched analysis (for case-control studies) * multivariate analysis

Question 111

when subjects with identical (or near identical) characteristics are selected across compared groups

Answer 111

matching

Question 112

separating study population into homogenous categories of a confounder

Answer 112

stratification _{eg. everyone's a smoker in the smoker stratum}

Question 113

mathematical model that can control for multiple confounders simultaneously

Answer 113

multivariate analysis