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Yr 6 Maya SFP > Study types > Flashcards

Study types Flashcards

1
Q

Definition of systematic review

A

review which identifes, appraises & synthesizes all evidence that meets pre-specified eligibility criteria for a specific research question

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2
Q

Definition of meta-analysis

A

statistical analysis that combines results of multiple scientific studies

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3
Q

Definition of RCT

A

comparison outcomes of group receiving intervention with control group

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4
Q

Definition of Prospective vs retrospective Cohort study

A

groups classified based on exposure followed up prospectively to analyse outcomes

groups classified based on outcome look at retrospectively to analyse exposures

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5
Q

Definition of Case-control study

A

groups classified based on outcome and analysed retrospectively regarding exposure

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6
Q

Definition of Cross-sectional study

A

survey of a defined population at a single point in time

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7
Q

Phase I Clinical Trial

A

These are “first in human” studies usually conducted on a small number of healthy volunteers to determine the tolerability and safety of a new drug, as well as its pharmacokinetics and pharmacodynamics

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8
Q

Phase II Clinical Trial

A

These are “dose-finding” trials usually on patients - a lower number than Phase III but larger than Phase I - assessing optimal dosing (giving different doses and following up to determine the efficacy and tolerability/toxicity) and efficacy (biological effect of the drug)

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9
Q

Phase III Clinical Trial

A

These trials assess the effectiveness of a new drug/ intervention, as compared to the gold standard therapy (whilst always ensuring its safety), to inform the value of the new intervention in clinical practice. They are usually multi-centre randomised control trials on large numbers of patients.

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10
Q

Post-marketing surveillance (Phase IV)

A

Monitors safety of the drug after it is being marketed (pharmacovigilance), to detect any rare or long-term adverse events or side effects that were not detected during previous trials

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11
Q

Randomisation

A

The process of assigning trial subjects to treatment or control groups using an element of chance, so that each participant has an equal chance of being allocated to either group.

This is to reduce allocation bias and balance known and unknown possible confounding factors, such that any difference between the two groups is purely by chance.

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12
Q

Stratified randomisation

A

Prevents imbalance between treatment groups for known factors that influence prognosis or treatment responsiveness. As a result, stratification may prevent type I error and improve power for small trials (<400 patients), but only when the stratification factors have a large effect on the prognosis.

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13
Q

Allocation concealment

A

Refers to masking the randomisation code or sequence before patients are recruited so that investigators don’t know what group the next patient will be randomised to, thus avoiding selection bias

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14
Q

Blinding

A

Involves masking the allocation of the treatment group after randomisation, so one or more parties involved in the trial are not aware whether the participants are in the intervention or control group. This aims to remove bias, including performance and observer bias.

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15
Q

Efficacy

A

The capacity for the therapeutic effect of a given intervention, e.g. whether a drug demonstrates a health benefit over a placebo or other intervention when tested in an ideal situation. These are called explanatory trials.

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16
Q

Effectiveness

A

How well an intervention works in practice, i.e. in the real world outside a clinical trial. This tends to be lower than the efficacy. There are called pragmatic trials

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17
Q

Placebo

A

Traditionally refers to a substance or treatment with no active therapeutic effect. In medical research, it is unethical to give a substance without therapeutic effect when one is available. Hence, a placebo refers to the control used, for example, the gold-standard intervention in which the intervention of interest is being measured against.

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18
Q

Surrogate endpoint

A

A variable that is relatively easily measured and which predicts a rare or distant outcome of the intervention tested. It is not a direct measure of either harm or clinical benefit.

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19
Q

Surrogate outcome

A

Markers that are substituted in for a clinical outcome e.g. ejection fraction as an indicator of disease severity in heart failure

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20
Q

Composite outcome
pros vs cons

A

A combination of variables e.g. a scoring tool. Useful when each variable in the scoring tool is rare as it gives power to the study. Difficult to interpret.

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21
Q

Internal validity

A

the degree to which the causal relationships found in a study can be trusted (with bias reducing this).

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22
Q

Secondary research

A

E.g. systematic review/literature review. This means research that amalgamates the results of many studies, largely negating the influence of bias on the results.

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23
Q

Advantages of SR and MA

A

More accurate assessment of the ‘true’ population effect.
Larger patient numbers lead to increased power and reduce type II error (which is the erroneous conclusion that an intervention has no effect).
Less bias (funnel plot → publication bias assessment, heterogeneity analysis → method and data collection)

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24
Q

Disadvantages of SR and MA

A

Direct comparisons between studies are difficult, due to differing methodology.
It can introduce types of bias (selection, publication (consider grey literature), and language bias (non-English articles), selective reporting bias)

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25
Q

Steps followed in a SR

A

Check for existing reviews/protocols
Identify your research question
Define inclusion/exclusion criteria
Search for studies
Select studies for inclusion based on pre-defined criteria
Extract data from included studies
Evaluated risk of bias of included studies
Present results and assess quality of evidence

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26
Q

Steps followed in a MA

A

Frame a question (based on a theory):
PICOK method.
Run a search
Screen
Extract data
Determine the quality of information in the articles (assess internal validity but also use GRADE criteria). Critically appraise the information contained within each study. You must decide if the study meets the internal validity criteria. A method to ascertain the quality of each outcome within an article is to use the GRADE criteria (grading recommendations assessment,
development, and evaluation).
Determine the extent to which these articles are heterogeneous.
Estimate the summary effect size in the form of ORs and using both fixed and random effects models.
Construct a forest plot
Determine the extent to which these articles have publication bias and run a funnel plot.
Conduct subgroup analyses and meta regression to test if there are subsets of research that capture the summary effects.

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27
Q

What is the problem with surrogate outcomes?

A

May not reflect outcomes that are important to patients

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28
Q

RCT pros

A

Gold standard for studying treatment effects
Random allocation reduces selection bias and equally distributes confounding factors between arms
Prospective: allows one to conclude causation between intervention and outcome (and outcomes determined a priori)
Reliably measures efficacy
Allows for meta-analyses

29
Q

RCT cons

A

Difficult
Time-consuming
Expensive
May be prone to underpowering
Ethical problems in giving different treatments to the groups

30
Q

Prospective cohort study pros

A

Can answer questions about aetiology and prognosis
Direct estimation of disease incidence rates
Can assess temporal relationships and causal links
Can assess multiple outcomes (that may be associated with multiple exposures…)
Good for rare exposures
Can estimate risk ratios and odds ratios

31
Q

Prospective cohort study cons

A

Can take a long time from exposure to measured outcomes
Cannot be used if diseases have long latency period
Expensive to set up and maintain
Bias is an issue if subjects drop out over time (often a large cohort is needed)

32
Q

Advantage of prospective vs. retrospective cohort studies

A

Prospective: able to control design, sampling, data collection and follow-up methods, and can measure all variables of interest.

Retrospective: time efficient and inexpensive, and easy to obtain large samples.

33
Q

Case-control pros

A

Good for studying rare disease
Useful when there is a long latency period between a risk factor and an outcome
Quick and cheap as few subjects required
Requires fewer patients - no loss to follow up

34
Q

Case-control cons

A

Can be difficult to match to the control group (a potential source of bias is the precise definition of who counts as a case. Subject to selection bias.)
Rely on recall and records to identify risk factors (recall bias)
Temporal relationship difficult as subjects forget about sequence of events (symptom appearance) - relies on reverse causation

35
Q

Retrospective design is susceptible to reverse causation. What is this?

A

A form of protopathic bias - this is when the applied treatment for disease appears to cause the outcome

36
Q

What do cross-sectional studies aim to do?

A

Cross-sectional studies aim to take an overview of the whole population (entire hospital population) and not a subgroup which is seen in case-control studies (pregnant women).

37
Q

What is a downside to cross-sectional studies?

A

It is purely descriptive and can only show correlation, not causation (e.g. pregnancy shown to correlate with deep vein thrombosis but not cause it).

38
Q

What is a case report?

A

An account of the presentation, diagnosis, treatment, and follow-up of an individual patient. Case reports often combine the accounts of multiple patients with similar presentations or diagnoses.

39
Q

What is the purpose of a case report?

A

They are often used to describe unusual associations between symptoms and disease, novel treatments, and new insights into the pathogenesis of a disease. The evidence produced is anecdotal and for that reason is often used as a springboard for more robust research e.g., a case-control study.

40
Q

The registration of clinical trials has been a formal condition of

A

Research Ethics Committee approval

41
Q

Registration of a trial should ideally occur

A

Before the first participant is recruited

42
Q

Randomisation techniques

A

Fixed randomisation: simple, block, stratified. Other: cluster, adaptive

43
Q

Ethical points to consider

A

Who funded the study? Conflicts of interest?
Study population? Able to consent? How recruited?
Intervention? Participants potentially being given an inferior treatment?
Risks or side effects?
Primary outcome?
Implications of trial?

44
Q

Autonomy

A

Respect for the patient’s right to self-determination

45
Q

Beneficence

A

Acting in the best interest of others

46
Q

Non-maleficence

A

Avoiding and minimising potential harm

47
Q

Justice

A

Ensuring fair allocation of resources

48
Q

The subject’s welfare and autonomy must always take preference over the benefit to science - true or false?

A

True

49
Q

What is a cross over trial?

A

All participants will be exposed to the intervention and control, in a random order, usually with a washout period inbetween

50
Q

Advantages of cross over

A

each subject acts as his or her own control, and that a smaller number of patients are required in comparison to parallel-group studies

51
Q

Disadvantages of cross over

A

LOTS
Longer in duration
Drop outs that only complete one treatmetnt contribute little the analysis
Carryover effect from one treatment to the next

52
Q

What is a nested case control study?

A

cases of a disease that occur in a defined cohort are identified and, for each, a specified number of matched controls is selected from among those in the cohort who have not developed the disease by the time of disease occurrence in the case

Differs from case-control study as controls are sampled from pre-defined source population with known sample size vs an unknown size for standard case-control

53
Q

Define parallel group

A

In parallel group randomisation, participants are randomised to one or two or more arms (groups), there should be an equal number in each arm

54
Q

Single vs double blind

A

In a single-blind study, patients do not know which study group they are in (for example whether they are taking the experimental drug or a placebo).

In a double-blind study, neither the patients nor the researchers/doctors know which study group the patients are in.

55
Q

Pros and cons of multicentre trials

A

Pros:
Increased generalisability
Shorter recruitment period
Diverse population
Larger sample size

Cons:
Methodological problems/inconsistencies
Centre-specific bias

56
Q

Superiority study design

A

a trial with the primary objective of showing that the response to the investigational product is superior to a comparative agent (active or placebo control).

57
Q

Non-inferiority study design

A

are intended to show that the effect of a new treatment is not worse than that of an active control by more than a specified margin.

58
Q

Random sampling

A

Each element in the population has an equal chance of occuring. While this is the preferred way of sampling, it is often difficult to do. It requires that a complete list of every element in the population be obtained. Computer generated lists are often used with random sampling.

59
Q

Systematic sampling

A

easier to do than random sampling
In systematic sampling, the list of elements is “counted off”. That is, every kth element is taken. This is similar to lining everyone up and numbering off “1,2,3,4; 1,2,3,4; etc”. When done numbering, all people numbered 4 would be used.

60
Q

Convenience sampling

A

very easy to do, but it’s probably the worst technique to use. In convenience sampling, readily available data is used. That is, the first people the surveyor runs into.

61
Q

Cluster sampling

A

dividing the population into groups – usually geographically. These groups are called clusters or blocks. The clusters are randomly selected, and each element in the selected clusters are used.

62
Q

Stratified sampling

A

divides the population into groups called strata. However, this time it is by some characteristic, not geographically. For instance, the population might be separated into males and females. A sample is taken from each of these strata using either random, systematic, or convenience sampling.

63
Q

Types of randomisation

A

Simple
Block
Stratified
Covariate Adaptive

64
Q

Nuremberg Code

A

a set of ethical research principles for human experimentation created by the court in U.S. v Brandt

Basic principles include:
voluntary consent of the human subject is absolutely essential
experiment should be such as to yield fruitful results for the good of society
experiment should be so designed and based on the results of animal experimentation and a knowledge of the natural history of the disease

65
Q

Declaration of Helsinki

A

The World Medical Association (WMA) has developed the Declaration of Helsinki as a statement of ethical principles for medical research involving human subjects, including research on identifiable human material and data

Basic priniciples:
Duty of researchers to protect the:
Life
Health
Dignity
Integrity
Right to self-determination
Privacy
Confidentiality

66
Q

Audit

A

the process of examining and reviewing documents and records to ensure accuracy, and that care complies with the current standards, rules and regulations within the medical field

67
Q

Quality improvement project

A

identifying a deficit in quality of care and aiming to improve, by making small cumulative changes and measuring their effects

68
Q

Audit vs QIP

A

Audits can improve the quality of care but by definition must compare current practice to a ‘standard’.

In contrast, QIPs allow creativity by enabling improvements in areas that might not have easily identifiable ‘standards’.

69
Q

Hierarchy of evidence

A
  1. Systematic reviews and meta-analyses
  2. RCTs
  3. Cohort studies
  4. Case-control studies
  5. Case series, Case reports
  6. Editorials, Expert opinion

Yr 6 Maya SFP (3 decks)

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