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Random Notes for Royal College Exam > Critical appraisal > Flashcards

Critical appraisal Flashcards

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1
Q

How do you calculate sensitivity?

A

Sensitivity

= TP/(TP+FN)

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2
Q

How do you calculate specificity?

A

Specificity

= TN/(FP+TN)

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3
Q

How do you calculate NPV?

A

= TN/(TN+FN)

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4
Q

How do you calculate PPV?

A

= TP/(TP+FP)

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5
Q

How do you calculate positive likelihood ratio?

A

= sensitivity/(1- specificity)

= [TP/(TP+FN)]/[1-(TN/(FP+TN))]

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6
Q

How do you calculate negative likelihood ratio?

A

= (1-sensitivity)/specificity

= [1-(TP/(TP+FN))]/[TN/(FP+TN)]

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7
Q

How do you calculate OR?

A

= (TPxTN)/(FPxFN)

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8
Q

How do you calculate RRR?

A

= 1-RR

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9
Q

How do you calculate NNT?

A

= 1/ARR

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10
Q

How do you calculate ARR?

A

= incidence in intervention group - incidence in control group

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11
Q

How do you calculate RR?

A

= incidence in intervention group/incidence in control group

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12
Q

What is the definition of sensitivity?

A

Given that a disease is present, what is the probability that the test is positive
SnOUT (likelihood positive test is positive)

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13
Q

What is the definition of specificity?

A

Given that the disease is absent, what is the probability that the test is negative
SpIN (likelihood negative test is negative)

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14
Q

What is the definition of positive predictive value (PPV)?

A

Given that the test is positive, the probability that the disease is present

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15
Q

What is the definition of negative predictive value?

A

Given that the test is negative, the probability that the disease is absent

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16
Q

What is a type I error?

A

The probability that the difference observed in a study sample is simply due to chance aka p value

17
Q

What is type II error?

A

Based on an estimate of the “true difference” between groups, what is the chance that the difference in the study sample will not be statistically significant

18
Q

What is power?

A

Power = 1 - Type II error

19
Q

What is the definition of number needed to treat (NNT)?

A

The number of patients who need to be treated in order to prevent one additional bad outcome

20
Q

What is the definition of internal validity?

A

The degree to which the study truly answers the question it poses

21
Q

What is the definition of external validity?

A

Can the study results be generalized to other populations

22
Q

What is clinical equipoise?

A

State of uncertainty as to the balance of benefits and harm that may result from two or more therapeutic regimens.

Indication for a RCT

23
Q

What is a meta-analysis?

A

A quantitative, formal, epidemiological study design used to systematically assess previous research studies to derive conclusions about that body of research

24
Q

What is a systematic review?

A

A systematic review summarizes the results of available carefully designed healthcare studies (RCT) and provides a high level of evidence on the effectiveness of health care interventions

25
Q

What is the difference between a systematic review and meta analysis?

A

A systematic review answers a defined research question by collecting and summarizing all empirical evidence that fits pre-specified eligibility criteria

A meta analysis is the use of statistical methods to summarize the results of these studies

26
Q

What is the interpretation of a forest plot?

A

Horizontal line = individual study with result as a box and the 95% CI as a line

If a study crosses the vertical line it means it crosses the null value

Diamond = average of all individual studies with the horizontal points of the diamond 95% CI

I2 statistic = heterogeneity of studies, if >50% means studies are inconsistent

27
Q

What is a cohort study?

A

A longitudinal study where you observe a group with a certain exposure over time and look for development of an outcome.

Retrospective or prospective

28
Q

What are the pros of a cohort study?

A
  • treatment not withheld
  • generally cheaper than RCTs
  • can estimate relative risk (incidence)
29
Q

What are the cons of a cohort study?

A
  • controls may be difficult to obtain
  • does not deal with unanticipated confounders
  • blinding is more challenging
  • can be expensive
  • challenging for rare diseases/outcomes
30
Q

What is a case control study?

A

Groups identified on the basis of OUTCOME (disease and control). Compare rates of exposure retrospectively. Can match cases and controls based on potential con founders. Can give an estimate of odds ratio

31
Q

What are the pros of a case control study?

A
  • relatively quick and cheap

* maybe the only feasible method to study rare disease of long lag from exposure to outcome

32
Q

What are the cons of a case control study?

A
  • recall/record bias
  • choice of controls can be problematic
  • does not deal with unanticipated confounders
  • no incidence rates/relative risk

Random Notes for Royal College Exam (23 decks)

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