Critical Appraisal RCT Introduction Flashcards

1
Q

Assessing Cause and Effect

A

Each individual is either exposed to the treatment or not
- Assess which ones had the outcome and which ones didn’t

All confounding variables should be kept the same with the only difference being exposure

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2
Q

How do biases arise

A

The only difference in groups should be the experimental intervention
- Biases results from differences in prognostic factors (Patient Characteristics)

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3
Q

Steps to practice EBM

A
  1. Ask
  2. Acquire
  3. Appraise
  4. Apply
  5. Act and Assess
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4
Q

Using pre-appraised resources

A

Have to be careful as individual studies can be misleading

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5
Q

Random Error
- What is it

A

Random Error: Pure chance causes differences

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6
Q

Systematic Error
- What is it

A

Systematic Error (Bias)
- Underestimation or Overestimation of underlying effects leading to Systematic Deviation from the underlying truth

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7
Q

Systematic Error
- Causes

A

Caused by a feature of the design or the conduct of the research study

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8
Q

Random Error vs Systematic Error

A

Random Error: Graph is spread out and more variable, mean is still the same
- Does not affect the mean

Systematic Error: Graph’s mean deviates from the original
- Affects the mean

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9
Q

EBCP definition

A

Evidence Based Clinical Practice
- Find the best available evidence from systematic reviews and meta analysis
- Determine the strength of those evidences
- How useful it the evidence’s result to the patient

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10
Q

Why is it important to study critical appraisals

A

To be able to assess the quality of studies and deal with misinformation

Be able to tell the difference from high and low quality research

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11
Q

Resources to find study synopses and critical appraisals

A

Wiki Journal Club

ACP Journal Club

RX Files

BMJ Evidence Based Medicine

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12
Q

Summary Resources

A

Dynamed

Lexidrugs

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13
Q

Major categories of bias

A
  1. Arises from randomization process
  2. Deviations from intended intervention
  3. Missing outcome data
  4. Measurement of the outcome
  5. Selection of the reported result
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14
Q

Steps to appraise a therapy trial (JAMA approach)

A
  1. Risk of Bias
  2. Clinical Relevance
  3. Applicable to Patient Care
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15
Q

Risk of Bias
- JAMA Approach

A
  • Was prognostic balance maintained beginning, during the study, and the end
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16
Q

Clinically Relevance
- JAMA Approach

A

How large is the treatment effect
How precise is the estimate of the treatment effect

17
Q

Applicable to Patient Care

A
  • Were the study patients similar to my patients
  • Were all important outcomes considered
  • Are the benefits worth the harms and costs
18
Q

Understanding Confidence Intervals
- 1.43 [0.51,4.05]

What does 1.43 mean

A

1.43 times / 43% more likely

For a good event
- Greater than 1 means more likely for good event
- Less than 1 means less likely for good event

19
Q

Understanding Confidence Intervals
- 1.43 [0.51,4.05]

What does 0.51 mean

A

Lower limit
- Cure rate are up to 50% / 0.50 times lower with duct tape

20
Q

Understanding Confidence Intervals
- 1.43 [0.51,4.05]

What does 4.05 mean

A

Upper limit
- Cure rate are up to 300% / 4 times higher with duct tape

21
Q

Understanding Confidence Intervals
- Sufficiently precise

A

If 95% CI crosses a decision threshold then the results are not sufficiently precise

If 95% CI does not cross a decision threshold then the results are sufficiently precise

22
Q

Relevance

A
  1. Does the info focus on outcomes patients care about
  2. Is the intervention feasible and is the problem it addresses common
  3. Would the information cause a change in practice

If yes to all 3 it is patient oriented evidence

23
Q

Validity

A

Technical rigor of the work (Is it accurate?)

24
Q

Work

A

Time, money, and effort to answer a question

25
Usefulness of Medical Information
(Relevance * Validity) / Work
26
Different Types of Bias
1. Detection Bias 2. Observer Bias 3. Publication Bias 4. Recall Bias 5. Selective Outcome Reporting Bias 6. Social Desirability Bias
27
Sources of Bias - Differences at the start of a study
Between group differences in prognosis
28
Reducing Bias - Differences at the start of a study
Randomization, Allocation concelment
29
Source of Bias - Differences that Occur as the study proceeds
Placebo Effect Co-intervention Bias in assessment of outcomes
30
Reducing Bias - Differences that Occur as the study proceeds (Placebo)
Blinding of Patients
31
Reducing Bias - Differences that Occur as the study proceeds (Co-intervention)
Blinding of caregivers
32
Reducing Bias - Differences that Occur as the study proceeds (Assessment)
Blinding of assessors of outcomes
33
Source of Bias - Differences at the Completion of the study
- Loss to follow-up - Stopping early because of large effect - Omitting patients who did not receive assigned treatment
34
Reducing Bias - Differences at the Completion of the study (Follow Up)
Ensure complete follow up
35
Reducing Bias - Differences at the Completion of the study (Stopping early)
Completing study as initially planned
36
Reducing Bias - Differences at the Completion of the study (Omitting patients)
Adhering to the intention to treat principle - Analyze patients in the arm where they were originally randomized