Revision Q Flashcards by Karen Gao

because of the epidemiological transition, the burden of infectious disease in developing countries is set to worsen

False

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infectious diseases are the leading cause of death in Sub-Saharan Africa

True

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chicken pox is one of the six most common causes of death from infectious disease worldwide

False

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Malaria is one of the six most common causes of death from infectious disease worldwide

True

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the best indicator of the burden of an infectious disease is the number of deaths

False

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If an exposure and disease are statistically associated this means that the exposure causes the disease

False

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evidence-based medicine has replaced clinical decision making over the last 30 years

False

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systematic reviews and meta-analyses are at the top of the hierarchy of evidence

True

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in the hierarchy of evidence, case-control studies provide stronger evidence than that from cohort studies

False

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What is the hierarchy of studies

Systematic review and meta analyses
RCT
Cohort study
Case control study
Ecological study
descriptive/cross sectional study
case report/series

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Definition of bias

A systematic error in design, conduct or analysis of a study which produces a mistaken estimate of an exposure on the risk of disease

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What are the critical features of a clinical trial?

Objectives
Patient selection
Controls
Study size
Unbiased data collection
Specific design
Ethics
Analysis

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What are the advantages to randomisation?

Validates statistics
excludes biased allocation
equally distributes prognostic factors of known and unknown

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Why use controls?

Placebo effect
regression to the mean
acclimatisation
seasonal effect
basis of study question

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What is a regression to the mean?

Any intervention at bad times will be followed by an improvement

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Bias in RCTs

Sponsorship
study patient allocation/selection
prejudice of patient
prejudice of observer
faulty method
faulty analysis
faulty interpretation

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The 95% confidence intervals provide information that helps us determine whether a statistical association between an exposure and disease (expressed as a relative risk or odds ratio) could have occurred by chance

True

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if increasing levels of an exposure lead to increasing risk of disease i.e. a dose-response relationship is found, this provides further evidence of causality

True

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The association being assessed is less likely to be causal if it is consistent with evidence from animal experiments and known biological mechanisms

False

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A lack of consistency between results from a number of studies using different study designs in different populations excludes a causal association

False

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A strong association, as measured by the magnitude of the relative risk, is more likely to be causal than a weak association

True

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for a putative risk factor to be the cause of a disease, it has to precede the disease

True

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there is a systematic difference between the observed association between exposure and disease and the true association between exposure and disease

True

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The presence of bias in an observational study of the effect of an exposure on disease risk implies: there are missing values in the response (disease outcome) measurements

False

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The presence of bias in an observational study of the effect of an exposure on disease risk implies: there is a systematic difference between the observed association between exposure and disease and the hypothesized association between exposure and disease

False

The presence of bias in an observational study of the effect of an exposure on disease risk implies: the estimated relative risk of disease associated with the exposure is inaccurate

True

The presence of bias in an observational study of the effect of an exposure on disease risk implies: there are missing values in the exposure measurements

False

a study to assess the effect of regular exercise on the risk of coronary heart disease, by collecting information on exercise via a questionnaire as part of a health and lifestyle survey Experimental?

False. Observational

a study of the prevalence of Down's syndrome in babies born in the UK between 1995 and 2000 Experimental?

No. Observational

a study to assess the effect of regular exercise on the risk of coronary heart disease, by randomly allocating some patients to take part in a supervised exercise programme and the remaining patients to take no additional exercise Experimental?

Yes

a comparison of glycaemic control (measured by plasma glycosylated haemoglobin levels) of patients with type 2 diabetes who were treated with either drug A or drug B in a randomized controlled trial Experimental?

Yes

a comparison of fasting glucose levels in patients with type 2 diabetes registered at a GP practice who were treated either with twice daily insulin therapy alone or with twice daily insulin therapy plus a new drug (Exenatide) claimed to boost the number of insulin-producing cells in the pancreas. Data on treatment regime were obtained from the GP's records Experimental?

No, observational

a study of the prevalence of Down's syndrome in babies born in the UK between 1995 and 2000 Experimental?

Observational

Prospective cohort studies cannot measure incidence

False

prospective cohort studies are necessary to estimate the prevalence of disease

False

Prospective cohort studies: select subjects for inclusion on the basis of their current disease status

False, A cohort study does not select subjects into a study on the basis of ANY disease status, including disease-free status. A cohort study selects a group of people e.g. a particular ethnic group, or from a particular area, or a particular age group, or of a particular occupation or lifestyle that they are likely to have high levels of the exposure/risk factor of interest e.g. a cohort of asbestos workers or a cohort of mobile phone subscribers. The exposure levels of the group are then characterised so that we know who has low/high exposure etc and we then follow the health of the cohort over time to obtain disease incidence. We then compare the disease incidence in the different exposure groups and assess the association between exposure and disease.

Prospective cohort studies: are studies where subjects are followed over time to determine the frequency of occurrence of the disease under study

True

Prospective cohort studies: can be subject to bias from the healthy worker effect

True

Specificity definition

Specificity (also called the true negative rate) measures the proportion of actual negatives that are correctly identified as such (e.g., the percentage of healthy people who are correctly identified as not having the condition).

Sensitivity definition

Sensitivity (also called the true positive rate, the recall, or probability of detection in some fields) measures the proportion of actual positives that are correctly identified as such (e.g., the percentage of sick people who are correctly identified as having the condition).

If the disease is rare then a population based approach is usually warranted

False

A population approach to vaccination is the most cost effective way of protecting children from measles.

True

Tertiary prevention is always preferable to other forms.

False

Screening may be primary or secondary prevention

False

Levels of health prevention?

Primordial Primary Secondary Tertiary

High risk approach to disease intervention?

Identify th special need targeted rescue operation, then controlling exposure, providing protection against exposure, screening among certain ethnic groups for specific disorders

Population approach to disease intervention?

Begin with recognition that the occurance of common diseases and exposures reflects the behaviour and circumstances of society as a whole

Primary prevention?

Prevent disease before it occurs

Secondary prevention?

Reduce impact of disease that has already occured

Tertiary prevention?

Soften impact of disease that is ongoing or has lasting effects

Treating high blood pressure is secondary prevention

Yes

Clinical trials often involve "double blinding" where both the researcher and the participants are unaware who is in the intervention or control group

True

Clinical trials: Phase IV clinical trials are post-marketing studies that aim to provide additional information on the drug's risks, benefits and optimal use

True

Clinical trials assign participants randomly to intervention and control groups for ethical reasons

False

Clinical trials are the only experimental design in epidemiology

True

Clinical trials: Phase II clinical trials aim to determine the metabolic and pharmacologic actions of drugs in humans and the maximum tolerated dose

False

Clinical trials stage 0

Whether the drug reaches the cancer How the drug behaves in the body How cells in the body respond to the drug

Clinical trials stage 1

How much of the drug is safe to give What the side effects are How the body copes with the drug If the treatment works

Clinical trials stage 2

If the new treatment works well enough to test in a larger phase 3 trial Which conditions the treatment works for More about side effects and how to manage them More about the best dose to use

Clinical trials stage 3

A completely new treatment with the standard treatment Different doses or ways of giving a standard treatment A new way of giving radiotherapy with the standard way Uses more people than stages 1 and 2

Clinical trials stage 4

More about the side effects and safety of the drug What the long term risks and benefits are How well the drug works when it’s used more widely

Meta-analyses; the random effects model should be used when it is reasonable to assume that the underlying treatment effect is the same in all studies that are part of the meta-analysis

False

Meta-analyses: Publication bias refers to the greater likelihood of research that has not found a significant result to be published in peer-reviewed literature compared to research that has found a significant result

False

Meta-analyses: the main difference between a systematic review and a meta-analysis is that the meta-analysis involves a quantitative method to calculate an overall summary (average) effect of a treatment/exposure

True

Meta-analyses should contain clearly defined eligibility criteria for the studies chosen to be included

True

Meta-analyses are original research studies

False

ASSERTION: The attributable risk is especially useful in evaluating the impact of introduction or removal of risk factors. REASON: The attributable risk will be the incidence of disease in the exposed divided by the incidence of disease in the unexposed.

Assertion True | Reason False, it is the difference between the incidence of the diseased and incidence of the unexposed

Attributable risk definition

difference between the risk of an outcome in the exposed group and the unexposed group

ASSERTION: Researchers following a group of 100 vegetarians and 200 non-vegetarians for heart disease incidence, report a relative risk of 0.8 and 95% confidence intervals of 0.6 to 0.9. Vegetarians were significantly less likely to develop heart disease than non-vegetarians. REASON: Where confidence intervals do not include 1, chance can be excluded as a likely explanation of the findings.

Assertion True Reason True Reason is a correct explanation

ASSERTION: Findings from a case control study can contribute evidence of the temporal sequence of events between exposure and disease. REASON: Bradford Hill criteria for causality include the temporal sequence of events between exposure and disease.

Assertion false | Reason True

ASSERTION: Health promotion initiatives in the UK include a Sure Start programme that provides effective parenting sessions for teenage parents on a council estate. REASON: Health promotion initiatives can include an educational component.

ASSERTION is True REASON is True REASON is correct explanation

ASSERTION: A meta analysis is at the top of the hierarchy of evidence. REASON: A meta analysis combines the results from individual studies to produce an overall effect estimate that is more reliable and precise.

ASSERTION is True REASON is True REASON is correct explanation

Revision Q Flashcards

(72 cards)