Causation & Study Design: HIV & AIDS Flashcards

Question 1

Q

Study designs

Which study design is reflected in each? (A-D)

Answer

A

Which study design is reflected in each? (A-D)
- A = Cross-Sectional
- B = Case-control
- C = Cohort
- D = Randomised Control Trial

Question 2

Q

Study designs

Which study design is reflected in each? (A-D)

Answer

A

Which study design is reflected in each? (A-D)
- A = Cross-Sectional
- B = Case-control
- C = Cohort
- D = Randomised Control Trial

Question 3

Q

Study designs

Which study design is reflected in each? (A-D)

Answer

A

Which study design is reflected in each? (A-D)
- A = Cross-Sectional
- B = Case-control
- C = Cohort
- D = Randomised Control Trial

Question 4

Q

Study designs

Which study design is reflected in each? (A-D)

Answer

A

Which study design is reflected in each? (A-D)
- A = Cross-Sectional
- B = Case-control
- C = Cohort
- D = Randomised Control Trial

Question 5

Q

Cross-sectional study

A defined population is surveyed to simultaneously measure
- …/ … status
- …
Sample selected using inclusion and exclusion criteria
- Different to case-control (sample selected based on outcome status)
- Different to cohort (sample based on exposure status)
Could be general population or clinic-based
Prevalence is reported for the population as a whole, and often for subgroups

Answer

A

A defined population is surveyed to simultaneously measure
- Disease/ condition status (e.g. infertility)
- Exposure (e.g. sedentary lifestyle, alcohol intake)
Sample selected using inclusion and exclusion criteria
- Different to case-control (sample selected based on outcome status)
- Different to cohort (sample based on exposure status)
Could be general population or clinic-based
Prevalence is reported for the population as a whole, and often for subgroups

Question 6

Q

Cross-sectional study

A defined population is surveyed to simultaneously measure
- Disease/ condition status (e.g. infertility)
- Exposure (e.g. sedentary lifestyle, alcohol intake)
Sample selected using … and … criteria
- Different to case-control (sample selected based on outcome status)
- Different to cohort (sample based on exposure status)
Could be general … or …-based
Prevalence is reported for the population as a whole, and often for subgroups

Answer

A

A defined population is surveyed to simultaneously measure
- Disease/ condition status (e.g. infertility)
- Exposure (e.g. sedentary lifestyle, alcohol intake)
Sample selected using inclusion and exclusion criteria
- Different to case-control (sample selected based on outcome status)
- Different to cohort (sample based on exposure status)
Could be general population or clinic-based
Prevalence is reported for the population as a whole, and often for subgroups

Question 7

Q

Cross-sectional study

A defined population is surveyed to simultaneously measure
- Disease/ condition status (e.g. infertility)
- Exposure (e.g. sedentary lifestyle, alcohol intake)
Sample selected using inclusion and exclusion criteria
- Different to case-control (sample selected based on … status)
- Different to cohort (sample based on exposure status)
Could be general population or clinic-based
Prevalence is reported for the population as a …, and often for …

Answer

A

A defined population is surveyed to simultaneously measure
- Disease/ condition status (e.g. infertility)
- Exposure (e.g. sedentary lifestyle, alcohol intake)
Sample selected using inclusion and exclusion criteria
- Different to case-control (sample selected based on outcome status)
- Different to cohort (sample based on exposure status)
Could be general population or clinic-based
Prevalence is reported for the population as a whole, and often for subgroups

Question 8

Q

Cross-sectional study

A defined population is surveyed to simultaneously measure
- Disease/ condition status (e.g. infertility)
- … (e.g. sedentary lifestyle, alcohol intake)
Sample selected using inclusion and exclusion criteria
- Different to case-control (sample selected based on outcome status)
- Different to cohort (sample based on … status)
Could be general population or clinic-based
Prevalence is reported for the population as a whole, and often for subgroups

Answer

A

A defined population is surveyed to simultaneously measure
- Disease/ condition status (e.g. infertility)
- Exposure (e.g. sedentary lifestyle, alcohol intake)
Sample selected using inclusion and exclusion criteria
- Different to case-control (sample selected based on outcome status)
- Different to cohort (sample based on exposure status)
Could be general population or clinic-based
Prevalence is reported for the population as a whole, and often for subgroups

Question 9

Q

Cohort study

Used to
- calculate … (new onset cases of a disease/condition/outcome)
- identify … (risk factors) for particular outcome
Participants selected into exposed vs non-exposed group (no allocation made by the researcher)
Two groups as similar as possible (e.g. age, gender, occupation, stage of illness, etc.)
- Variables not of interest are matched (i.e. potential confounders) at selection
- Exposures of interest are not measured or matched at selection
At study end, relative numbers of new disease occurrences compared across groups
Retrospective or prospective

Answer

A

Used to
- calculate incidence (new onset cases of a disease/condition/outcome)
- identify exposures (risk factors) for particular outcome
Participants selected into exposed vs non-exposed group (no allocation made by the researcher)
Two groups as similar as possible (e.g. age, gender, occupation, stage of illness, etc.)
- Variables not of interest are matched (i.e. potential confounders) at selection
- Exposures of interest are not measured or matched at selection
At study end, relative numbers of new disease occurrences compared across groups
Retrospective or prospective

Question 10

Q

Cohort study

Used to
- calculate incidence (new onset cases of a disease/condition/outcome)
- identify exposures (risk factors) for particular outcome
Participants selected into … vs non-… group
Two groups as … as possible (e.g. age, gender, occupation, stage of illness, etc.)
- Variables not of interest are matched (i.e. potential confounders) at selection
- Exposures of interest are not measured or matched at selection
At study end, relative numbers of new disease occurrences compared across groups
Retrospective or prospective

Answer

A

Used to
- calculate incidence (new onset cases of a disease/condition/outcome)
- identify exposures (risk factors) for particular outcome
Participants selected into exposed vs non-exposed group (no allocation made by the researcher)
Two groups as similar as possible (e.g. age, gender, occupation, stage of illness, etc.)
- Variables not of interest are matched (i.e. potential confounders) at selection
- Exposures of interest are not measured or matched at selection
At study end, relative numbers of new disease occurrences compared across groups
Retrospective or prospective

Question 11

Q

Cohort study

Used to
- calculate … (new onset cases of a disease/condition/outcome)
- identify exposures (risk factors) for particular outcome
Participants selected into exposed vs non-exposed group (no allocation made by the researcher)
Two groups as similar as possible (e.g. age, gender, occupation, stage of illness, etc.)
- Variables not of interest are matched (i.e. potential confounders) at selection
- Exposures of interest are not measured or matched at selection
At study end, relative numbers of new disease occurrences compared across …
Retrospective or prospective

Answer

A

Used to
- calculate incidence (new onset cases of a disease/condition/outcome)
- identify exposures (risk factors) for particular outcome
Participants selected into exposed vs non-exposed group (no allocation made by the researcher)
Two groups as similar as possible (e.g. age, gender, occupation, stage of illness, etc.)
- Variables not of interest are matched (i.e. potential confounders) at selection
- Exposures of interest are not measured or matched at selection
At study end, relative numbers of new disease occurrences compared across groups
Retrospective or prospective

Question 12

Q

Cohort study

Used to
- calculate incidence (… … cases of a disease/condition/outcome)
- identify exposures (… …) for particular outcome
Can be …spective or ….spective

Answer

A

Used to
- calculate incidence (new onset cases of a disease/condition/outcome)
- identify exposures (risk factors) for particular outcome
Can be retrospective or prospective

Question 13

Q

Case-control study

Used to identify relevant … (not used to calculate …)
Two groups of participants are selected – one with condition (cases) and one without (controls)
Controls selected to be as similar as possible to the cases (e.g. age, gender, occupation, stage of illness, etc.)
- Variables not of interest are matched (i.e. potential confounders) at selection
- Exposures of interest are not measured or matched at selection
Always …→Past exposure/s in both groups
- E.g. interview/survey, historical records

Answer

A

Used to identify relevant exposures (not used to calculate incidence)
Two groups of participants are selected – one with condition (cases) and one without (controls)
Controls selected to be as similar as possible to the cases (e.g. age, gender, occupation, stage of illness, etc.)
- Variables not of interest are matched (i.e. potential confounders) at selection
- Exposures of interest are not measured or matched at selection
Always retrospective→Past exposure/s in both groups
- E.g. interview/survey, historical records

Question 14

Q

Case-control study

Used to identify relevant exposures (not used to calculate incidence)
Two groups of participants are selected – one with condition (…) and one without (…)
Controls selected to be as … as possible to the … (e.g. age, gender, occupation, stage of illness, etc.)
- Variables not of interest are matched (i.e. potential confounders) at selection
- Exposures of interest are not measured or matched at selection
Always retrospective→Past exposure/s in both groups
- E.g. interview/survey, historical records

Answer

A

Used to identify relevant exposures (not used to calculate incidence)
Two groups of participants are selected – one with condition (cases) and one without (controls)
Controls selected to be as similar as possible to the cases (e.g. age, gender, occupation, stage of illness, etc.)
- Variables not of interest are matched (i.e. potential confounders) at selection
- Exposures of interest are not measured or matched at selection
Always retrospective→Past exposure/s in both groups
- E.g. interview/survey, historical records

Question 15

Q

Case-control study

Used to identify relevant exposures (not used to calculate incidence)
Two groups of participants are selected – one with condition (cases) and one without (controls)
Controls selected to be as similar as possible to the cases (e.g. age, gender, occupation, stage of illness, etc.)
- Variables not of interest are matched (i.e. potential …) at selection
- Exposures of interest are … … or matched at selection
Always retrospective→Past exposure/s in both groups
- E.g. interview/survey, historical records

Answer

A

Used to identify relevant exposures (not used to calculate incidence)
Two groups of participants are selected – one with condition (cases) and one without (controls)
Controls selected to be as similar as possible to the cases (e.g. age, gender, occupation, stage of illness, etc.)
- Variables not of interest are matched (i.e. potential confounders) at selection
- Exposures of interest are not measured or matched at selection
Always retrospective→Past exposure/s in both groups
- E.g. interview/survey, historical records

Question 16

Q

Case-control study

Used to identify relevant exposures (not used to calculate …)
Two groups of participants are selected – one with condition (cases) and one without (controls)
Controls selected to be as similar as possible to the cases (e.g. age, gender, occupation, stage of illness, etc.)
- Variables not of interest are matched (i.e. potential confounders) at selection
- Exposures of interest are not measured or matched at selection
Always retrospective→… …/s in both groups
- E.g. interview/survey, historical records

Answer

A

Used to identify relevant exposures (not used to calculate incidence)
Two groups of participants are selected – one with condition (cases) and one without (controls)
Controls selected to be as similar as possible to the cases (e.g. age, gender, occupation, stage of illness, etc.)
- Variables not of interest are matched (i.e. potential confounders) at selection
- Exposures of interest are not measured or matched at selection
Always retrospective→Past exposure/s in both groups
- E.g. interview/survey, historical records

Question 17

Q

Cohort studys can be retrospective or prospective, but case-control studies are always …

Answer

A

retrospective

Question 18

Q

RCT

Used to test the … and …/… of interventions
Participants selected and then randomly allocated to either receive the intervention of interest or to receive a control (or no) intervention
Random allocation should ensure that the two groups are essentially identical before provision of intervention or control
Outcomes are compared across the two groups at the end of the trial

Answer

A

Used to test the safety and efficacy/effectiveness of interventions
Participants selected and then randomly allocated to either receive the intervention of interest or to receive a control (or no) intervention
Random allocation should ensure that the two groups are essentially identical before provision of intervention or control
Outcomes are compared across the two groups at the end of the trial

Question 19

Q

RCT

Used to test the safety and efficacy/effectiveness of interventions
Participants selected and then … allocated to either receive the …. of interest or to receive a …
Random allocation should ensure that the two groups are essentially identical before provision of intervention or control
Outcomes are compared across the two groups at the end of the trial

Answer

A

Used to test the safety and efficacy/effectiveness of interventions
Participants selected and then randomly allocated to either receive the intervention of interest or to receive a control (or no) intervention
Random allocation should ensure that the two groups are essentially identical before provision of intervention or control
Outcomes are compared across the two groups at the end of the trial

Question 20

Q

RCT

Used to test the safety and efficacy/effectiveness of interventions
Participants selected and then randomly allocated to either receive the intervention of interest or to receive a control (or no) intervention
Random allocation should ensure that the two groups are essentially … before provision of intervention or control
Outcomes are … across the two groups at the end of the trial

Answer

A

Used to test the safety and efficacy/effectiveness of interventions
Participants selected and then randomly allocated to either receive the intervention of interest or to receive a control (or no) intervention
Random allocation should ensure that the two groups are essentially identical before provision of intervention or control
Outcomes are compared across the two groups at the end of the trial

Question 21

Q

RCT

Used to test the … and …/effectiveness of interventions
Participants selected and then randomly allocated to either receive the intervention of interest or to receive a control (or no) intervention
… allocation should ensure that the two groups are essentially identical before provision of intervention or control
Outcomes are compared across the two groups at the end of the trial

Answer

A

Used to test the safety and efficacy/effectiveness of interventions
Participants selected and then randomly allocated to either receive the intervention of interest or to receive a control (or no) intervention
Random allocation should ensure that the two groups are essentially identical before provision of intervention or control
Outcomes are compared across the two groups at the end of the trial

Question 22

Q

Why do we need to think about causation?

Question 23

Q

Differences between study designs

Question 24

Q

Differences between study designs

List in order (top to bottom) - Cohort, Cross-sectional, Case control, RCT, Case Study

Question 25

Q

Which study design gives the best evidence for causal association?

Question 26

Q

A … is a variable that influences both the dependent variable and independent variable causing a spurious association

Answer

A

A confounder is a variable that influences both the dependent variable and independent variable causing a spurious association

Question 27

Q

Confounding

Influences both … and …

Answer

A

Influences both exposure and disease

Question 28

Q

Causal criteria

… postulates – causal factors in infectious disease
…-Hill criteria – causal factors in sickness, injury and occupation

Answer

A

Koch’s postulates – causal factors in infectious disease
Bradford-Hill criteria – causal factors in sickness, injury and occupation

Question 29

Q

Causal criteria

Koch’s … – causal factors in … disease
Bradford-… criteria – causal factors in …, injury and occupation

Answer

A

Koch’s postulates – causal factors in infectious disease
Bradford-Hill criteria – causal factors in sickness, injury and occupation

Question 30

Q

Causal criteria

Koch’s postulates – causal factors in … disease
Bradford-Hill criteria – causal factors in sickness, … and occupation

Answer

A

Koch’s postulates – causal factors in infectious disease
Bradford-Hill criteria – causal factors in sickness, injury and occupation

Question 31

Q

Causal criteria

… postulates – causal factors in infectious disease
Bradford-Hill criteria – causal factors in sickness, injury and …

Answer

A

Koch’s postulates – causal factors in infectious disease
Bradford-Hill criteria – causal factors in sickness, injury and occupation

Question 32

Q

Bradford-Hill criteria

Question 33

Q

Bradford-Hill criteria

Question 34

Q

Bradford-Hill criteria

Question 35

Q

Koch’s postulates

Question 36

Q

Koch’s postulates

The bacteria must be … in … case of the disease.
The bacteria must be isolated from the host with the disease and grown in pure culture.
The specific disease must be reproduced when a pure culture of the bacteria is inoculated into a healthy susceptible host.
The bacteria must be recoverable from the experimentally infected host.

Answer

A

The bacteria must be present in every case of the disease.
The bacteria must be isolated from the host with the disease and grown in pure culture.
The specific disease must be reproduced when a pure culture of the bacteria is inoculated into a healthy susceptible host.
The bacteria must be recoverable from the experimentally infected host.

Question 37

Q

Koch’s postulates

The bacteria must be present in every case of the disease.
The bacteria must be … from the host with the disease and … in pure culture.
The specific disease must be reproduced when a pure culture of the bacteria is inoculated into a healthy susceptible host.
The bacteria must be recoverable from the experimentally infected host.

Answer

A

The bacteria must be present in every case of the disease.
The bacteria must be isolated from the host with the disease and grown in pure culture.
The specific disease must be reproduced when a pure culture of the bacteria is inoculated into a healthy susceptible host.
The bacteria must be recoverable from the experimentally infected host.

Question 38

Q

Koch’s postulates

The bacteria must be present in every case of the disease.
The bacteria must be isolated from the host with the disease and grown in pure culture.
The specific disease must be … when a pure culture of the bacteria is inoculated into a … susceptible host.
The bacteria must be recoverable from the experimentally infected host.

Answer

A

The bacteria must be present in every case of the disease.
The bacteria must be isolated from the host with the disease and grown in pure culture.
The specific disease must be reproduced when a pure culture of the bacteria is inoculated into a healthy susceptible host.
The bacteria must be recoverable from the experimentally infected host.

Question 39

Q

Koch’s postulates

The bacteria must be present in every case of the disease.
The bacteria must be isolated from the host with the disease and grown in pure culture.
The specific disease must be reproduced when a pure culture of the bacteria is inoculated into a healthy susceptible host.
The bacteria must be … from the … infected host.

Answer

A

The bacteria must be present in every case of the disease.
The bacteria must be isolated from the host with the disease and grown in pure culture.
The specific disease must be reproduced when a pure culture of the bacteria is inoculated into a healthy susceptible host.
The bacteria must be recoverable from the experimentally infected host.

Question 40

Q

HIV/AIDS

… … Virus infection / Acquired Immune Deficiency Syndrome (HIV/AIDS)
A spectrum of conditions caused by infection with the … … Virus (HIV)
HIV targets cells within the immune system, causing immunodeficiency→disease and opportunistic infections which would typically normally be neutralised
Discovered in 1981 in USA – the AIDS crisis
Global pandemic, responsible for at least 35 million deaths worldwide; c. 350,000 men and women in the USA died between 1987 and 1998

Answer

A

Human Immunodeficiency Virus infection / Acquired Immune Deficiency Syndrome (HIV/AIDS)
A spectrum of conditions caused by infection with the Human Immunodeficiency Virus (HIV)
HIV targets cells within the immune system, causing immunodeficiency→disease and opportunistic infections which would typically normally be neutralised
Discovered in 1981 in USA – the AIDS crisis
Global pandemic, responsible for at least 35 million deaths worldwide; c. 350,000 men and women in the USA died between 1987 and 1998

Question 41

Q

HIV/AIDS

Human Immunodeficiency Virus infection / Acquired Immune Deficiency Syndrome (HIV/AIDS) A spectrum of conditions caused by infection with the Human Immunodeficiency Virus (HIV)
HIV targets cells within the immune system, causing …→disease and opportunistic infections which would typically normally be …
Discovered in 1981 in USA – the AIDS crisis
Global pandemic, responsible for at least 35 million deaths worldwide; c. 350,000 men and women in the USA died between 1987 and 1998

Answer

A

Human Immunodeficiency Virus infection / Acquired Immune Deficiency Syndrome (HIV/AIDS) A spectrum of conditions caused by infection with the Human Immunodeficiency Virus (HIV)
HIV targets cells within the immune system, causing immunodeficiency→disease and opportunistic infections which would typically normally be neutralised
Discovered in 1981 in USA – the AIDS crisis
Global pandemic, responsible for at least 35 million deaths worldwide; c. 350,000 men and women in the USA died between 1987 and 1998

Question 42

Q

HIV/AIDS

Human Immunodeficiency Virus infection / Acquired Immune Deficiency Syndrome (HIV/AIDS) A spectrum of conditions caused by infection with the Human Immunodeficiency Virus (HIV)
HIV targets cells within the immune system, causing immunodeficiency→disease and opportunistic infections which would typically normally be neutralised
Discovered in … in USA – the AIDS crisis
Global pandemic, responsible for at least … million deaths worldwide; c. 350,000 men and women in the USA died between 1987 and 1998

Answer

A

Human Immunodeficiency Virus infection / Acquired Immune Deficiency Syndrome (HIV/AIDS) A spectrum of conditions caused by infection with the Human Immunodeficiency Virus (HIV)
HIV targets cells within the immune system, causing immunodeficiency→disease and opportunistic infections which would typically normally be neutralised
Discovered in 1981 in USA – the AIDS crisis
Global pandemic, responsible for at least 35 million deaths worldwide; c. 350,000 men and women in the USA died between 1987 and 1998

Question 43

Q

HIV/AIDS

Human Immunodeficiency Virus infection / Acquired Immune Deficiency Syndrome (HIV/AIDS) A spectrum of conditions caused by infection with the Human Immunodeficiency Virus (HIV)
HIV targets cells within the immune system, causing immunodeficiency→disease and … infections which would typically normally be neutralised
Discovered in 1981 in USA – the AIDS crisis
Global …, responsible for at least 35 million deaths worldwide; c. 350,000 men and women in the USA died between 1987 and 1998

Answer

A

Human Immunodeficiency Virus infection / Acquired Immune Deficiency Syndrome (HIV/AIDS) A spectrum of conditions caused by infection with the Human Immunodeficiency Virus (HIV)
HIV targets cells within the immune system, causing immunodeficiency→disease and opportunistic infections which would typically normally be neutralised
Discovered in 1981 in USA – the AIDS crisis
Global pandemic, responsible for at least 35 million deaths worldwide; c. 350,000 men and women in the USA died between 1987 and 1998

Question 44

Q

AIDS: Contribution of study designs

… … help when disease is new, when first cases are being discovered
After this - which study design?
Then -

Answer

A

Case studies help when disease is new, when first cases are being discovered
After this - which study design - Cross-sectional
Then - Case control

Question 45

Q

AIDS: Contribution of study designs

Which study design for each?

Answer

A

Case studies
Cross-sectional
Case control

Question 46

Q

AIDS Cohort studies

Immediately after initial recognition of AIDS, epidemiologists in the United States, Denmark, and the Netherlands established cohort studies of … men, injection drug users, and people with …
Then the larger Multicenter AIDS Cohort Study (MACS) which was launched in 1984
- 1) describe the early pathophysiologic events in the course leading to AIDS-related conditions [and] AIDS…,
- 2) define and quantify the factors suspected of initiating or modulating the immunopathologic process leading to AIDS…,
- [and] 3) provide access to a repository of biologic specimens with detailed epidemiologic data for investigators with promising ideas for research

Answer

A

Immediately after initial recognition of AIDS, epidemiologists in the United States, Denmark, and the Netherlands established cohort studies of homosexual men, injection drug users, and people with hemophilia
Then the larger Multicenter AIDS Cohort Study (MACS) which was launched in 1984
- 1) describe the early pathophysiologic events in the course leading to AIDS-related conditions [and] AIDS…,
- 2) define and quantify the factors suspected of initiating or modulating the immunopathologic process leading to AIDS…,
- [and] 3) provide access to a repository of biologic specimens with detailed epidemiologic data for investigators with promising ideas for research

Question 47

Q

AIDS Cohort studies

Immediately after initial recognition of AIDS, epidemiologists in the United States, Denmark, and the Netherlands established cohort studies of homosexual men, injection drug users, and people with hemophilia
Then the larger Multicenter AIDS Cohort Study (…) which was launched in …
- 1) describe the early pathophysiologic events in the course leading to AIDS-related conditions [and] AIDS…,
- 2) define and quantify the factors suspected of initiating or modulating the immunopathologic process leading to AIDS…,
- [and] 3) provide access to a repository of biologic specimens with detailed epidemiologic data for investigators with promising ideas for research

Answer

A

Immediately after initial recognition of AIDS, epidemiologists in the United States, Denmark, and the Netherlands established cohort studies of homosexual men, injection drug users, and people with hemophilia
Then the larger Multicenter AIDS Cohort Study (MACS) which was launched in 1984
- 1) describe the early pathophysiologic events in the course leading to AIDS-related conditions [and] AIDS…,
- 2) define and quantify the factors suspected of initiating or modulating the immunopathologic process leading to AIDS…,
- [and] 3) provide access to a repository of biologic specimens with detailed epidemiologic data for investigators with promising ideas for research

Question 48

Q

AIDS Cohort studies

Immediately after initial recognition of AIDS, epidemiologists in the United States, Denmark, and the Netherlands established cohort studies of homosexual men, injection drug users, and people with hemophilia
Then the larger Multicenter AIDS Cohort Study (MACS) which was launched in 1984
- 1) describe the early … events in the course leading to AIDS-related conditions [and] AIDS…,
- 2) define and quantify the … suspected of initiating or modulating the immunopathologic process leading to AIDS…,
- [and] 3) provide access to a repository of biologic specimens with detailed epidemiologic data for investigators with promising ideas for research

Answer

A

Immediately after initial recognition of AIDS, epidemiologists in the United States, Denmark, and the Netherlands established cohort studies of homosexual men, injection drug users, and people with hemophilia
Then the larger Multicenter AIDS Cohort Study (MACS) which was launched in 1984
- 1) describe the early pathophysiologic events in the course leading to AIDS-related conditions [and] AIDS…,
- 2) define and quantify the factors suspected of initiating or modulating the immunopathologic process leading to AIDS…,
- [and] 3) provide access to a repository of biologic specimens with detailed epidemiologic data for investigators with promising ideas for research

Question 49

Q

AIDS Cohort studies

Immediately after initial recognition of AIDS, epidemiologists in the United States, Denmark, and the Netherlands established cohort studies of homosexual men, injection drug users, and people with hemophilia
Then the larger Multicenter AIDS Cohort Study (MACS) which was launched in 1984
- 1) describe the early pathophysiologic events in the course leading to AIDS-related conditions [and] AIDS…,
- 2) define and quantify the factors suspected of initiating or modulating the … process leading to AIDS…,
- [and] 3) provide access to a repository of biologic … with detailed epidemiologic data for investigators with promising ideas for research

Answer

A

Immediately after initial recognition of AIDS, epidemiologists in the United States, Denmark, and the Netherlands established cohort studies of homosexual men, injection drug users, and people with hemophilia
Then the larger Multicenter AIDS Cohort Study (MACS) which was launched in 1984
- 1) describe the early pathophysiologic events in the course leading to AIDS-related conditions [and] AIDS…,
- 2) define and quantify the factors suspected of initiating or modulating the immunopathologic process leading to AIDS…,
- [and] 3) provide access to a repository of biologic specimens with detailed epidemiologic data for investigators with promising ideas for research

Question 50

Q

The contribution of MACS

Over 1,500 papers, 4 which have been cited more than 1000 times;
- Fahey et al. (1990), in which researchers validated serum levels of neopterin and β2-microglobulin, in combination with the CD4 T-cell count, as biomarkers of AIDS risk;
- Dean et al. (1996), in which they described the profound protection against HIV infection by a genetic variant of a co-receptor for HIV on CD4 T-cells;
- Mellors et al. (1996), in which the authors identified the level of HIV circulating in plasma (i.e., HIV viral load) as a strong prognostic indicator; and
- Mellors et al. (1997), in which they established the combined measurement of HIV viral load and CD4 T- cell count as a highly accurate predictor of prognosis.
MACS is being combined with a …-focused cohort WIHS-CISS which still continues to date.

Answer

A

Over 1,500 papers, 4 which have been cited more than 1000 times;
- Fahey et al. (1990), in which researchers validated serum levels of neopterin and β2-microglobulin, in combination with the CD4 T-cell count, as biomarkers of AIDS risk;
- Dean et al. (1996), in which they described the profound protection against HIV infection by a genetic variant of a co-receptor for HIV on CD4 T-cells;
- Mellors et al. (1996), in which the authors identified the level of HIV circulating in plasma (i.e., HIV viral load) as a strong prognostic indicator; and
- Mellors et al. (1997), in which they established the combined measurement of HIV viral load and CD4 T- cell count as a highly accurate predictor of prognosis.
MACS is being combined with a female-focused cohort WIHS-CISS which still continues to date.

Question 51

Q

The contribution of MACS

Over 1,500 papers, 4 which have been cited more than 1000 times;
- Fahey et al. (1990), in which researchers validated serum levels of neopterin and β2-microglobulin, in combination with the CD4 T-cell count, as biomarkers of AIDS risk;
- Dean et al. (1996), in which they described the profound protection against HIV infection by a genetic variant of a co-receptor for HIV on CD4 T-cells;
- Mellors et al. (1996), in which the authors identified the level of HIV circulating in plasma (i.e., HIV viral load) as a strong prognostic indicator; and
- Mellors et al. (1997), in which they established the combined measurement of HIV viral load and CD4 T- cell count as a highly accurate predictor of prognosis.
MACS is being combined with a female-focused cohort WIHS-CISS which still continues to date.

Answer

A

Over 1,500 papers, 4 which have been cited more than 1000 times;
- Fahey et al. (1990), in which researchers validated serum levels of neopterin and β2-microglobulin, in combination with the CD4 T-cell count, as biomarkers of AIDS risk;
- Dean et al. (1996), in which they described the profound protection against HIV infection by a genetic variant of a co-receptor for HIV on CD4 T-cells;
- Mellors et al. (1996), in which the authors identified the level of HIV circulating in plasma (i.e., HIV viral load) as a strong prognostic indicator; and
- Mellors et al. (1997), in which they established the combined measurement of HIV viral load and CD4 T- cell count as a highly accurate predictor of prognosis.
MACS is being combined with a female-focused cohort WIHS-CISS which still continues to date.

Question 52

Q

Causation and confounding

Answer

A

Close association between male circumcision and HIV/AIDS prevalence
- 1) male circumcision causes a reduction in the chance of contracting HIV/AIDS
OR
- 2) some other factor increases chance of being uncircumcised and chance of contracting HIV/AIDS

Question 53

Q

Causation and cofounding - HIV/AIDs and male circumcision

Close association between male circumcision and HIV/AIDS prevalence
- 1) male circumcision … a … in the chance of contracting HIV/AIDS
OR
- 2) some other … increases chance of being … and chance of contracting HIV/AIDS
Can it tell us if either, or both or not?

Answer

A

Close association between male circumcision and HIV/AIDS prevalence
- 1) male circumcision causes a reduction in the chance of contracting HIV/AIDS
OR
- 2) some other factor increases chance of being uncircumcised and chance of contracting HIV/AIDS
Can’t tell us - RCT come in handy here

Question 54

Q

Causation and confounding - Male circumcision and HIV/AIDS

Analytic - experimental
- 3 RCTs; South Africa (N= 3274), Uganda (N= 4996), and Kenya (N= 2784) Does Adult male circumcision reduce risk of HIV acquisition in men?
  - RR of 0.50 at 12 months [CIs 0.34, 0.72]
- Meta-analysis secondary outcomes (Cochrane Review)
  - Suggested only one sig. difference in sexual behaviour in one trial (circumcised men 1 more sexual contact at 12m)
Why?
- Foreskin increases risk of micro tears during sex
- Foreskin provides hospitable environment for pathogen survival

Answer

A

Analytic - experimental
- 3 RCTs; South Africa (N= 3274), Uganda (N= 4996), and Kenya (N= 2784) Adult male circumcision reduces risk of HIV acquisition in men by c. 60%
  - RR of 0.50 at 12 months [CIs 0.34, 0.72]
- Meta-analysis secondary outcomes (Cochrane Review)
  - Suggested only one sig. difference in sexual behaviour in one trial (circumcised men 1 more sexual contact at 12m)
Why?
- Foreskin increases risk of micro tears during sex
- Foreskin provides hospitable environment for pathogen survival

Question 55

Q

Causation and confounding - Male circumcision and HIV/AIDS

Analytic - experimental
- 3 RCTs; South Africa (N= 3274), Uganda (N= 4996), and Kenya (N= 2784) Does Adult male circumcision reduce risk of HIV acquisition in men?

Answer

A

Analytic - experimental
- 3 RCTs; South Africa (N= 3274), Uganda (N= 4996), and Kenya (N= 2784) Adult male circumcision reduces risk of HIV acquisition in men by c. 60%
  - RR of 0.50 at 12 months [CIs 0.34, 0.72]
- Meta-analysis secondary outcomes (Cochrane Review)
  - Suggested only one sig. difference in sexual behaviour in one trial (circumcised men 1 more sexual contact at 12m)
Why?
- Foreskin increases risk of micro tears during sex
- Foreskin provides hospitable environment for pathogen survival

Question 56

Q

Causation and confounding - Male circumcision and HIV/AIDS

Analytic - experimental
- 3 RCTs; South Africa (N= 3274), Uganda (N= 4996), and Kenya (N= 2784) Adult male circumcision reduces risk of HIV acquisition in men by c. 60%
  - RR of 0.50 at 12 months [CIs 0.34, 0.72]
- Meta-analysis secondary outcomes (… Review)
  - Suggested only … sig. difference in sexual behaviour in one trial
Why?
- Foreskin increases risk of micro tears during sex
- Foreskin provides hospitable environment for pathogen survival

Answer

A

Analytic - experimental
- 3 RCTs; South Africa (N= 3274), Uganda (N= 4996), and Kenya (N= 2784) Adult male circumcision reduces risk of HIV acquisition in men by c. 60%
  - RR of 0.50 at 12 months [CIs 0.34, 0.72]
- Meta-analysis secondary outcomes (Cochrane Review)
  - Suggested only one sig. difference in sexual behaviour in one trial (circumcised men 1 more sexual contact at 12m)
Why?
- Foreskin increases risk of micro tears during sex
- Foreskin provides hospitable environment for pathogen survival

Question 57

Q

Causation and confounding - Male circumcision and HIV/AIDS

Analytic - experimental
- 3 RCTs; South Africa (N= 3274), Uganda (N= 4996), and Kenya (N= 2784) Adult male circumcision reduces risk of HIV acquisition in men by c. 60%
  - RR of 0.50 at 12 months [CIs 0.34, 0.72]
- Meta-analysis secondary outcomes (Cochrane Review)
  - Suggested only one sig. difference in sexual behaviour in one trial (circumcised men 1 more sexual contact at 12m)
Why?
- Foreskin increases risk of … … during sex
- Foreskin provides … environment for pathogen …

Answer

A

Analytic - experimental
- 3 RCTs; South Africa (N= 3274), Uganda (N= 4996), and Kenya (N= 2784) Adult male circumcision reduces risk of HIV acquisition in men by c. 60%
  - RR of 0.50 at 12 months [CIs 0.34, 0.72]
- Meta-analysis secondary outcomes (Cochrane Review)
  - Suggested only one sig. difference in sexual behaviour in one trial (circumcised men 1 more sexual contact at 12m)
Why?
- Foreskin increases risk of micro tears during sex
- Foreskin provides hospitable environment for pathogen survival

Question 58

Q

Koch’s posulates - HIV/AIDS

Question 59

Q

Koch’s posulates - HIV/AIDS

Question 60

Q

Bradford-Hill criteria - HIV/AIDS

Question 61

Q

Bradford-Hill criteria - HIV/AIDS

Question 62

Q

Bradford-Hill criteria - HIV/AIDS

Question 63

Q

Summary - Causation and Study Design - HIV/AIDS

Four key types of study design- ….
- … (3) = analytic-observational, … = analytic-experimental, … = best
evidence for causal association between exposure/s and outcome/s
When a study finds an association between one thing and another thing, it does not mean one thing caused the other to happen
Koch’s postulates; presence of microorganism in diseased organism, microorganism can be isolated and cultured, introduction of microorganism to healthy organism leads to disease, microorganism can be re-isolated from inoculated, disease organism and identified as identical to the original agent
Bradford-Hill criteria; Strength of association, Consistency, Specificity, Temporality, Biological gradient, Plausibility, Coherence, Experimental evidence, Analogy
We can use different study designs to satisfy causal factors and determine the likelihood of an exposure being causative of a disease outcome

Answer

A

Four key types of study design- cross-sectional, cohort (retro/prospective), case control, RCT
- Cross-sectional, cohort, case control = analytic-observational, RCT = analytic-experimental, RCT = best
evidence for causal association between exposure/s and outcome/s
When a study finds an association between one thing and another thing, it does not mean one thing caused the other to happen
Koch’s postulates; presence of microorganism in diseased organism, microorganism can be isolated and cultured, introduction of microorganism to healthy organism leads to disease, microorganism can be re-isolated from inoculated, disease organism and identified as identical to the original agent
Bradford-Hill criteria; Strength of association, Consistency, Specificity, Temporality, Biological gradient, Plausibility, Coherence, Experimental evidence, Analogy
We can use different study designs to satisfy causal factors and determine the likelihood of an exposure being causative of a disease outcome

Question 64

Q

Summary - Causation and Study Design - HIV/AIDS

Four key types of study design- cross-sectional, cohort (retro/prospective), case control, …
- Cross-sectional, cohort, case control = analytic-observational, … = analytic-experimental, … = best
evidence for causal association between exposure/s and outcome/s
When a study finds an association between one thing and another thing, it does not mean one thing caused the other to happen
… postulates; presence of microorganism in diseased organism, microorganism can be isolated and cultured, introduction of microorganism to healthy organism leads to disease, microorganism can be re-isolated from inoculated, disease organism and identified as identical to the original agent
…-Hill criteria; Strength of association, Consistency, Specificity, Temporality, Biological gradient, Plausibility, Coherence, Experimental evidence, Analogy
We can use different study designs to satisfy causal factors and determine the likelihood of an exposure being causative of a disease outcome

Answer

A

Four key types of study design- cross-sectional, cohort (retro/prospective), case control, RCT
- Cross-sectional, cohort, case control = analytic-observational, RCT = analytic-experimental, RCT = best
evidence for causal association between exposure/s and outcome/s
When a study finds an association between one thing and another thing, it does not mean one thing caused the other to happen
Koch’s postulates; presence of microorganism in diseased organism, microorganism can be isolated and cultured, introduction of microorganism to healthy organism leads to disease, microorganism can be re-isolated from inoculated, disease organism and identified as identical to the original agent
Bradford-Hill criteria; Strength of association, Consistency, Specificity, Temporality, Biological gradient, Plausibility, Coherence, Experimental evidence, Analogy
We can use different study designs to satisfy causal factors and determine the likelihood of an exposure being causative of a disease outcome

Answer 52

A

Four key types of study design- cross-sectional, cohort (retro/prospective), case control, RCT
- Cross-sectional, cohort, case control = analytic-observational, RCT = analytic-experimental, RCT = best
evidence for causal association between exposure/s and outcome/s
When a study finds an association between one thing and another thing, it does not mean one thing caused the other to happen
Koch’s postulates; presence of microorganism in diseased organism, microorganism can be isolated and cultured, introduction of microorganism to healthy organism leads to disease, microorganism can be re-isolated from inoculated, disease organism and identified as identical to the original agent
Bradford-Hill criteria; Strength of association, Consistency, Specificity, Temporality, Biological gradient, Plausibility, Coherence, Experimental evidence, Analogy
We can use different study designs to satisfy causal factors and determine the likelihood of an exposure being causative of a disease outcome

Answer 53

A

Four key types of study design- cross-sectional, cohort (retro/prospective), case control, RCT
- Cross-sectional, cohort, case control = analytic-observational, RCT = analytic-experimental, RCT = best
evidence for causal association between exposure/s and outcome/s
When a study finds an association between one thing and another thing, it does not mean one thing caused the other to happen
Koch’s postulates; presence of microorganism in diseased organism, microorganism can be isolated and cultured, introduction of microorganism to healthy organism leads to disease, microorganism can be re-isolated from inoculated, disease organism and identified as identical to the original agent
Bradford-Hill criteria; Strength of association, Consistency, Specificity, Temporality, Biological gradient, Plausibility, Coherence, Experimental evidence, Analogy
We can use different study designs to satisfy causal factors and determine the likelihood of an exposure being causative of a disease outcome

Answer 54

A

Four key types of study design- cross-sectional, cohort (retro/prospective), case control, RCT
- Cross-sectional, cohort, case control = analytic-observational, RCT = analytic-experimental, RCT = best
evidence for causal association between exposure/s and outcome/s
When a study finds an association between one thing and another thing, it does not mean one thing caused the other to happen
Koch’s postulates; presence of microorganism in diseased organism, microorganism can be isolated and cultured, introduction of microorganism to healthy organism leads to disease, microorganism can be re-isolated from inoculated, disease organism and identified as identical to the original agent
Bradford-Hill criteria; Strength of association, Consistency, Specificity, Temporality, Biological gradient, Plausibility, Coherence, Experimental evidence, Analogy
We can use different study designs to satisfy causal factors and determine the likelihood of an exposure being causative of a disease outcome

Answer 55

A

Four key types of study design- cross-sectional, cohort (retro/prospective), case control, RCT
- Cross-sectional, cohort, case control = analytic-observational, RCT = analytic-experimental, RCT = best
evidence for causal association between exposure/s and outcome/s
When a study finds an association between one thing and another thing, it does not mean one thing caused the other to happen
Koch’s postulates; presence of microorganism in diseased organism, microorganism can be isolated and cultured, introduction of microorganism to healthy organism leads to disease, microorganism can be re-isolated from inoculated, disease organism and identified as identical to the original agent
Bradford-Hill criteria; Strength of association, Consistency, Specificity, Temporality, Biological gradient, Plausibility, Coherence, Experimental evidence, Analogy
We can use different study designs to satisfy causal factors and determine the likelihood of an exposure being causative of a disease outcome