Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

HYMS phase II H&S > Critical appraisal > Flashcards

Critical appraisal Flashcards

1
Q

What 4 factors are involved when making an evidence based decision?

A

1) Evidence from research
2) Clinical expertise
3) Available resources
4) Patient preferences

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

State 3 reasons why we need evidence based medicine.

A

1) Increases medical knowledge
2) There is limited time to read
3) Traditional resources such as books can prove to be inadequate (are often out of date)
4) There is a disparity between diagnostic skills/ clinical judgement and up to date knowledge.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is evidence based medicine?

A

A process for identifying and using the most up to date and relevant evidence to inform decisions for individual patient problems.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Give 3 reasons why evidence based medicine is possible.

A

1) The development of strategies for effectively identifying and appraising evidence.
2) The creation of systematic reviews and summaries
3) The creation of evidence-based journals and clinical guidelines
4) The creation of information systems
5) The identification and application of strategies for lifelong learning.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are background questions?

A

Background questions are informational questions that improve the understanding of a topic.

The questions usually have one or two concepts and do not require the process used in formulating a research or evidence based decision-making questions.

They basically ask general knowledge about a disorder.

E.G. What causes breast cancer?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are foreground questions?

A

Foreground questions ask for specific knowledge to inform clinical decisions.

These questions typically concern a specific patient or particular population.
Foreground questions tend to be more specific and complex compared to background questions.

E.G. In younger women with breast cancer, is mastectomy with chemotherapy more effective than mastectomy done alone, in reducing the risk of cancer recurrence?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are typically the 4 essential components to a foreground question?

A

1) Patient, problem, population
2) Intervention
3) Comparison intervention/ control
4) Clinical outcomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

When asking foreground questions, accuracy can be classed as what?

A

Having a low false positive rate and a low false negative rate.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the aspects of a PICO question?

A
  • Patient/ population/ problem
  • Intervention
  • Comparator/ control
  • Outcome
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the aspects of a PEO question?

A
  • Population/ patient/ problem
  • Exposure
  • Outcome
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

When are PEO questions used over PICO questions?

A

When there is no obvious control group.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Which studies are used for the following question types?

1) Diagnosis
2) Aetiology/ harm
3) Prognosis
4) Treatment
5) Evaluation

A

1) Cross sectional analytical study/ SR
2) Cohort study/ population based case-control study/ SR
3) Cohort study/SR
4) RCT/ SR of RCTs
5) Qualitative research/ SR/ meta-analysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the difference between case-control and cohort studies?

A

Case control studies are retrospective. Cohort studies follow people prospectively.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe 3 benefits of systematic reviews over individual primary studies.

A

1) Include all available research evidence to answer a question.
2) Include research that is unpublished or has been published in non-English language journals.
3) Increase the total sample size (increases levels of certainty and precision).
4) Indicate heterogeneity (variation) among studies
5) Permit sub-group analyses
6) Permit sensitivity analysis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is bias?

A

The systematic introduction of error into a study that can distort the results in a non-random way.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the 3 discrete steps in appraising some evidence?

A

1) Are the results of the study valid?
2) What are the results?
3) Can I apply the results to this patient’s care?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What 5 things must you assess a research study for?

A

1) Bias
2) Applicability
3) Limits
4) Value
5) Whether the evidence provided is useful for patient care.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

In terms of results, what must you report for studies looking at each of the following factors?

1) Therapy (RCT)
2) Diagnosis
3) Prognosis
4) Aetiology/ harm

A

1) Relative risk reduction, absolute risk reduction, odds ration, NNT, confidence intervals.
2) Sensitivity, specific, PPV, NPV, likelihood ratios.
3) Likelihood of outcomes overtime, how precise prognosis estimates are (relative risk/ odds ratio).
4) Relative risk, odds ration, NNtH.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What must you consider when deciding if you can use the results of a study?

A

GENERALISABILITY:

1) How similar are the patients in the study to your patient?
2) Can the local health service provide the intervention/ diagnostic test?
3) What are the benefits and costs (potential harms/ financial costs)?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

For systematic reviews, state what must be considered for each of the following questions:

1) Did the review ask a clearly focused question?
2) Did the review include the right type of study?

A

1) Consider if the question is focused in terms of: the population studied, the intervention given/ the exposure and the outcomes considered.
2) Consider if the included studies: address the review’s question and have an appropriate study design.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

For systematic reviews, state what must be considered for each of the following questions:

1) Did the reviewers try to identify all relevant studies?

A

Consider:

  • which bibliographic databases were used.
  • if there was a follow-up from the reference list.
  • if there was personal contact with experts.
  • if the reviewers searched for unpublished studies.
  • if the reviewers searched for non-English language studies.

**Increases the number of studies and ensures all relevant studies (incl. those with null or negative results) are included in the review.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

For systematic reviews, state what must be considered for each of the following questions:

1) Did the reviewers assess the quality of the included studies?

A

Consider:

  • if a clear, pre-determined strategy was used to determine which studies were included.
  • a scoring system
  • more than one assessor.

**Look for individual studies assessed for quality by more than one reviewer, using standard criteria. This means that it is more likely that only studies of good quality are included.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

For systematic reviews, state what must be considered for each of the following questions:

1) If the results of the studies have been combined, was it reasonable to do so?

A

Consider whether:

  • the results of each study are clearly displayed.
  • the results were similar from study to study.
  • the reasons for any variations in results are discussed.

**If studies are very dissimilar, then results should not be combined. Combined results provide stronger evidence, but only when it is appropriate to do so.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

For systematic reviews, state what must be considered for each of the following questions:

1) How are the results presented and what is the main result?

A

Consider:

  • how the results are expressed (odds ratio/ relative risk, etc)
  • how large this size of result is and how meaningful it is.
  • how you would sum up the bottom-line result in one sentence.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

For systematic reviews, state what must be considered for each of the following questions:

1) How precise are these results?

A

Consider:

  • if a confidence interval were reported.
  • would your decision about whether or not to use this intervention be the same at the upper confidence limit as at the lower confidence limit?
  • if a p-value is reported where confidence intervals are unavailable.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

For systematic reviews, state what must be considered for each of the following questions:

1) Can the results be applied to the local population?

A

Consider whether:

  • the population sample covered by the review could be different from your population in ways that would produce a different result.
  • your local setting differs much from that of the review.
  • you can provide the same intervention in your setting.

**Because SRs can use heterogenous study populations, there may be details on sub-groups.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

For systematic reviews, state what must be considered for each of the following questions:

1) Were all important outcomes considered?
2) Should policy or practice change as a result of the evidence contained in this review?

A

1) Consider outcomes from the POV of the individual, policy makers and professionals, family/ carers and the wider community.
2) Consider whether any benefit reported outweighs any harm and/or cost. If this information is not reported, can it be filled in from elsewhere?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

For randomised control trials, state what must be considered for each of the following questions:

1) Did the study ask a clearly focused question?
2) Was this a randomised control trial and was it appropriately so?

A

1) Consider if the question is focused in terms of: population studied, intervention given and outcomes considered.
2) Consider why this study was carried out as an RCT and if this was the right research approach for the question being asked.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

For randomised control trials, state what must be considered for each of the following questions:

1) Were participants appropriately allocated to intervention and control groups?

A

Consider:

  • how participants were allocated to intervention and control groups. Was the process truly random?
  • whether the method of allocation was described. Was a method used to balance the randomisation, e.g. stratification?
  • how the randomisation schedule was generated and how a participant was allocated to a study group
  • if the groups were well balanced. Are any differences between the groups at entry to the trial reported?
  • if there were differences reported that might have explained any outcome(s) (confounding)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

For randomised control trials, state what must be considered for each of the following questions:

1) Were participants, staff and study personnel ‘blind’ to participants’ study group?

A

Consider:

  • the fact that blinding is not always possible
  • if every effort was made to achieve blinding
  • if you think it matters in this study
  • the fact that we are looking for ‘observer bias’
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

For randomised control trials, state what must be considered for each of the following questions:

1) Were all of the participants who entered the trial accounted for at its conclusion?

A

Consider:

  • if any intervention-group participants got a control group option or vice versa.
  • if all participants were followed up in each study group (was there loss-to-follow-up?)
  • if all the participants’ outcomes were analysed by the groups to which they are originally allocated (intention to treat analysis).
  • what additional information would you liked to have seen to make you feel better about this.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

For randomised control trials, state what must be considered for each of the following questions:

1) Were the participants in all groups followed up and data collected in the same way?
2) Did the study have enough participants to minimise the play of chance?

A

1) if, for example, they were reviewed at the same time intervals and if they received the same amount of attention from researchers and health workers. Any differences may introduce performance bias.
2) if there is a power calculation. This will estimate how many participants are needed to be reasonably sure of finding something important (if it really exists and for a given level of uncertainty about the final result).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

For randomised control trials, state what must be considered for each of the following questions:

1) How are the results presented and what is the main result?

A

Consider:

1) if, for example, the results are presented as a proportion of people experiencing an outcome, such as risks, or as a measurement, such as mean or median differences, or as survival curves and hazards
2) how large this size of result is and how meaningful it is
3) how you would sum up the bottom-line result of the trial in one sentence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

For randomised control trials, state what must be considered for each of the following questions:

1) How precise are the results?

A

Consider:

1) if the result is precise enough to make a decision
2) if a confidence interval were reported. Would your decision about whether or not to use this intervention be the same at the upper confidence limit as at the lower confidence limit?
3) if a p-value is reported where confidence intervals are unavailable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

For randomised control trials, state what must be considered for each of the following questions:

1) Were all important outcomes considered so the results can be applied?

A

Consider whether:

1) the people included in the trial could be different from your population in ways that would produce different results
2) your local setting differs much from that of the trial
3) you can provide the same treatment in your setting

Consider outcomes from the point of view of the:

1) Individual
2) policy makers and professionals
3) family/ carers
4) wider community

Consider whether:

1) any benefit reported outweighs any harm and/or cost. If this information is not reported can it be filled in from elsewhere?
2) policy or practice should change as a result of the evidence contained in this trial

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What is meant by the term ‘statistical power’?

A

Statistical power, or the power of a hypothesis test is the probability that the test correctly rejects the null hypothesis. That is, the probability of a true positive result. It is only useful when the null hypothesis is rejected.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What does a statistical power of 80% mean?

A

0% power in a clinical trial means that the study has a 80% chance of ending up with a p value of less than 5% in a statistical test (i.e. a statistically significant treatment effect) if there really was an important difference (e.g. 10% versus 5% mortality) between treatments.

38
Q

For a cohort study, state what must be considered for each of the following questions:

1) Did the study address a clearly focussed question?

A

Consider:

  • the population studied
  • the risk factors studied
  • the outcomes considered
  • is it clear whether the study tried to detect a beneficial or harmful effect?
39
Q

For a cohort/ case-control study, state what must be considered for each of the following questions:

1) Did the study address a clearly focussed question?

A

Consider:

  • the population studied
  • the risk factors studied
  • the outcomes considered
  • is it clear whether the study tried to detect a beneficial or harmful effect?
40
Q

For a cohort/ case-control study, state what must be considered for each of the following questions:

1) Did the authors use an appropriate method to answer their question?

A

Consider:

  • Is a cohort/ case-control study a good way of answering the question under the circumstances?
  • Did it address the study question?
41
Q

For a cohort study, state what must be considered for each of the following questions:

1) Was the exposure accurately measured to minimise bias?

A

We are looking for measurement or classification bias:

  • Did they use subjective or objective measurements?
  • Do the measures truly reflect what you want them to (have they been validated)?
  • Were all the subjects classified into exposure groups using the same procedure?
42
Q

For a cohort study, state what must be considered for each of the following questions:

1) Was the outcome accurately measured to minimise bias?

A

HINT: We are looking for measurement or classification bias:

  • Did they use subjective or objective measurements?
  • Do the measures truly reflect what you want them to (have they been validated)?
  • Has a reliable system been established for detecting all the cases (for measuring disease occurrence)?
  • Were the measurement methods similar in the different groups?

-Were the subjects and/or the outcome assessor blinded to exposure
(does this matter)?

43
Q

For a cohort study, state what must be considered for each of the following questions:

1) Have the authors identified all important confounding factors? List the ones you think might be important but the author has missed.
1a) Have they taken account of the confounding factors in the design and/ or analysis?

A

HINT:

Look for restriction in design, and techniques eg
modelling, stratified-, regression-, or sensitivity
analysis to correct, control or adjust for confounding factors

44
Q

For a cohort study, state what must be considered for each of the following questions:

1) Was the follow up of subjects complete enough?
1a) Was the follow up of subjects long enough?

A
  • The good or bad effects should have had
    long enough to reveal themselves.
  • The persons that are lost to follow-up may
    have different outcomes than those available for assessment
  • In an open or dynamic cohort, was there
    anything special about the outcome of the people leaving, or the exposure of the people entering the cohort?
45
Q

For a cohort study, state what must be considered for each of the following questions:

1) What are the results of this study?

A
  • What are the bottom line results?
  • Have they reported the rate or the proportion
    between the exposed/unexposed, the ratio/the rate
    difference?
  • How strong is the association between exposure and
    outcome (RR,)?
  • What is the absolute risk reduction (ARR)?
46
Q

For a cohort study, state what must be considered for each of the following questions:

1) How precise are the results? How precise is the estimate of the risk?

A

Consider the size of the confidence intervals.

47
Q

For a cohort study, state what must be considered for each of the following questions:

1) Do you believe the results?

A
  • Big effect is hard to ignore!
  • Can it be due to bias, chance or confounding?
  • Are the design and methods of this study
    sufficiently flawed to make the results unreliable?
  • Consider Bradford Hills criteria (eg time sequence,
    dose-response gradient, biological plausibility, consistency).
48
Q

For a cohort study, state what must be considered for each of the following questions:

1) Can the results be applied to the local population?

A

Consider whether:

  • The subjects covered in the study could be sufficiently different from your population to cause concern.
  • Your local setting is likely to differ much from that of the study
  • Can you quantify the local benefits and harms?

**Always consider if the results of the study fit with other available evidence as recommendations from observational studies are always stronger when supported by other evidence.

49
Q

For a case control study, state what must be considered for the following question:

were the cases recruited in an acceptable way?

A

HINT: We are looking for selection bias which might compromise the validity of
the findings:

  • Are the cases defined precisely?
  • Were the cases representative of a defined
    population (geographically and/or
    temporally)?
  • Was there an established reliable system for
    selecting all the cases?
  • Are they incident or prevalent?
  • Is there something special about the cases?
  • Is the time frame of the study relevant to the
    disease/exposure?
  • Was there a sufficient number of cases
    selected?
  • Was there a power calculation?
50
Q

For a case control study, state what must be considered for the following question:

were the cases recruited in an acceptable way?

A

HINT: We are looking for selection bias which might compromise the validity of
the findings:

  • Are the cases defined precisely?
  • Were the cases representative of a defined
    population (geographically and/or
    temporally)?
  • Was there an established reliable system for
    selecting all the cases?
  • Are they incident or prevalent?
  • Is there something special about the cases?
  • Is the time frame of the study relevant to the
    disease/exposure?
  • Was there a sufficient number of cases
    selected?
  • Was there a power calculation?
51
Q

For a case control study, state what must be considered for the following question:

were the controls recruited in an acceptable way?

A

HINT: We are looking for selection bias which might compromise the generalisability of the findings:

  • Were the controls representative of a defined population (geographically and/or temporally)?
  • Was there something special about the controls?
  • Was the non-response high? Could non- respondents be different in any way?
  • Are they matched, population based or randomly selected?
  • Was there a sufficient number of controls selected?
52
Q

For a case control study, state what must be considered for the following question:

Was the exposure accurately measured to minimise bias?

A

HINT: We are looking for measurement, recall or classification bias:

  • Was the exposure clearly defined and accurately measured?
  • Did the authors use subjective or objective measurements?
  • Do the measures truly reflect what they are supposed to measure? (have they been validated)?
  • Were the measurement methods similar in cases and controls?
  • Did the study incorporate blinding where feasible?
  • Is the temporal relation correct (does the exposure of interest precede the outcome?)
53
Q

For a case control study, state what must be considered for the following question:

1) What confounding factors have the authors accounted for? List the other ones that you think might be important but the authors missed.
1b) Have the authors taken account of the potential confounding factors in the design and/ or in their analysis?

A

HINT:

Look for restriction in design, and techniques
e.g. modelling, stratified-, regression-, or sensitivity analysis to correct, control or adjust for confounding factors.

54
Q

For a case control study, state what must be considered for the following question:

What are the results of this study?

A

Consider:

  • What are the bottom line results?
  • Is the analysis appropriate to the design?
  • How strong is the association between exposure and
    outcome (look at the odds ratio)?
  • Are the results adjusted for confounding and might
    confounding still explain the association?
  • Has adjustment made a big difference to the OR ??
55
Q

For a case control study, state what must be considered for the following question:

How precise are the results?

A

Consider:
- Size of the P-value

  • Size of the confidence intervals
  • Have the authors considered all the important
    variables?
  • How was the effect of subjects refusing to participate
    evaluated?
56
Q

For a case control study, state what must be considered for the following question:

Do you believe the results?

A
  • Big effect is hard to ignore!
  • Can it be due to chance, bias or confounding?
  • Are the design and methods of this study sufficiently
    flawed to make the results unreliable?
  • Consider Bradford Hills criteria (e.g. time sequence,
    dose-response gradient, strength, biological plausibility)
57
Q

For a case control study, state what must be considered for the following question:

Can the results be applied to the local population?

A

Consider whether:

  • The subjects covered in the study could be sufficiently different from your population to cause concern.
  • Your local setting is likely to differ much from that of the study.
  • Can you estimate the local benefits and harms?
58
Q

For a case control study, state what must be considered for the following question:

Do the results of this study fit with other available evidence?

A

HINT:

Consider all the available evidence from RCTs, systematic reviews, cohort studies and case-control studies as well for consistency.

**Recommendations from observational studies are always stronger when supported by other evidence.

59
Q

What is selection bias?

A

Error in the process of selecting participants for the study and assigning them to particular arms of the study.

**Bias introduced by the selection of individuals, groups or data for analysis in such a way that proper randomization is not achieved, thereby ensuring that the sample obtained is not representative of the population intended to be analyzed

60
Q

What is attrition bias?

A

Occurs when those patients who are lost to follow-up differ in a systematic way to those who did return for assessment or clinic.

**Bias that arises from systematic differences in the way participants are lost from a study.

61
Q

What is measurement bias?

A

Measurement bias refers to any systematic or non-random error that occurs in the collection of data in a study.

**when information is recorded in a distorted manner (e.g. an inaccurate measurement tool).

62
Q

What is observer bias?

A

Occurs when variables are reported differently between assessors.

63
Q

What is procedure bias?

A

Occurs when subjects in different arms of the study are treated differently (other than the exposure or intervention).

64
Q

What is misclassification bias?

A

Occurs when a study participant is categorised into an incorrect category altering the observed association or research outcome of interest.

**Basically occurs when a variable is classified incorrectly.

65
Q

What is information bias?

A

Information bias is any systematic difference from the truth that arises in the collection, recall, recording and handling of information in a study, including how missing data is dealt with.

**Happens when key information is either measured, collected, or interpreted inaccurately.

66
Q

What are the 4 major types of information bias?

A

Misclassification bias
Observer bias
Recall bias
Reporting bias

67
Q

What are Bradford Hill criteria used for?

A

The Bradford Hill criteria are a group of nine principles which can be useful in establishing epidemiological evidence of a causal relationship between a presumed cause and an observed effect.

**They describe reasons that indicate causality.

68
Q

What are the 9 Bradford Hill criteria?

A

1) strength of association
2) consistency
3) specificity
4) temporality
5) biological gradient
6) plausibility
7) coherence
8) experiment
9) analogy

69
Q

What is confounding?

A

Happens when a relationship between an exposure and an outcome is distorted by their shared relationship with another variable.

70
Q

Name 4 ways in which confounding can be addressed in study design and/or analysis.

A

1) Restriction
2) Matching
3) Stratification
4) Mutliple variable regression

71
Q

How is restriction carried out in terms of addressing confounding variables?

A
  • exclusion of participants with the identified confounding factor
  • means that you will have less data
  • difficult to implement when there are multiple confounding factors.
72
Q

How is matching carried out in terms of addressing confounding variables?

A
  • equal distribution among exposed and unexposed groups of the variables believed to be confounding variable.
  • used commonly in case-control studies
  • used for strong confounders like age and sex
  • not the most effective answer to most confounding variables
73
Q

How is stratification carried out in terms of addressing confounding variables?

A
  • an analytical approach where exposure: outcome associations are categorised into different subgroups of the confounder.
  • different subgroups are known as different strata.
74
Q

How is multiple variable regression carried out in terms of addressing confounding variables?

A

Allows us to estimate the association between a given independent variable and the outcome holding all other variables constant.

It provides a way of adjusting for (or accounting for) potentially confounding variables that have been included in the model.

75
Q

What is the additional step required if using stratification to manage confounding factors?

A

Adjustment.

The final step in stratified analysis is to recombined the results of the strata to get an adjustment measure of effect.

76
Q

What is a limitation of stratification and how can this be overcome?

A

If all potential confounders were stratified, then each strata would have very few people in it and so there would be very little data available to use.

Regression is used in some cases and this is a mathematical model used to ‘fill in the gaps’.

77
Q

Give 3 examples of confounding factors.

A

1) Age
2) Sex
3) Smoking status
4) Socioeconomic status

78
Q

What is evidence based decision making?

A

The process for identifying and using the most up to date and relevant evidence to inform decisions for individual patient problems.

79
Q

What does critical appraisal assess a research study for?

A

Bias, applicability and value.

CA identifies whether the evidence a study provides is useful for patient care.

80
Q

What does phase III of a clinical trial often involve?

A

RCTs with one or more experimental treatments being compared against control/ standard treatments.

Attempts are made to draw a definite conclusion regarding benefit or otherwise.

81
Q

What is the best method of allocation in an RCT?

A

An independent organisation who centrally organise randomised allocation via a computer programme.

This is designed to be unpredictable and is the least subject to potential subversion of the allocation process.

82
Q

What are the advantages of a systematic review?

A
  • All available evidence
  • Published/Unpublished research
  • Increased total sample size = certainty and precision
  • Indicated heterogeneity
  • Subgroup and sensitivity analyses
83
Q

What are the disadvantages of a systematic review?

A
  • Researcher can only use published or readily available studies
  • Conclusions may be unreliable
  • Unpublished studies may be hard to find
  • Results that are negative or inconclusive may remain unpublished
84
Q

What are the advantages of an RCT?

A
  • Causal inferences
  • Randomisation minimises bias
  • Tailored to a specific research question
85
Q

What are the disadvantages of an RCT?

A
  • Not always ethical
  • High dropout when intervention has undesirable effects
  • Expensive
86
Q

What are the advantages of cohort studies?

A 
-Measurement of exposure to risk
factor(s) not biased by the presence or absence of outcome
-Can provide data on time course of
development of an
outcome
-More than one
outcome can be
examined at once 
-Useful for
investigating rare exposures
87
Q

What are the disadvantages of cohort studies?

A
  • Potential for bias due to selection of subjects
  • Danger of losses to follow-up OR historical studies dependent on accuracy of records/ family/ patient recall
  • Exposure to risk factors/existence of prognostic factors may change over course of study
  • Can be timely and costly to carry out (e.g. some cohort studies can last for 20 years or more)
88
Q

What are the advantages of case-control studies?

A
  • Rare disease, long latency
  • Less costly and time consuming
  • Studying dynamic populations in which follow up is difficult
89
Q

What are the disadvantages of case-control studies?

A
  • Subject to selection bias
  • Inefficient for rare exposures
  • Subject to observation bias
  • Hard to calculate incidence
  • Bias and confounding.
  • Recall bias
90
Q

Describe what is meant by the following Bradford Hill criteria:

1) Strength of association
2) Temporal association
3) Consistency

A

1) Small vs. large association and statistical significance.
2) The effect has to occur after the cause.
3) Are findings consistent with other knowns?

91
Q

Describe what is meant by the following Bradford Hill criteria:

1) Theoretical plausibility
2) Coherence
3) Specificity

A

1) Not everything that is implausible is false.
2) Coherence between epidemiological and laboratory findings increases the likelihood of an effect.
3) Does this cause only lead to this effect?

92
Q

Describe what is meant by the following Bradford Hill criteria:

1) Dose-response relationship
2) Experimental evidence
3) Analogy

A

1) Does more of cause = more effect?
2) Strong vs. weak evidence. Some things you cannot test experimentally.
3) The effect of similar factors may be considered.

HYMS phase II H&S (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions