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MFSRH > CRQ > Flashcards

CRQ Flashcards

1
Q

Hierarchy of evidence

A 
Meta analysis
Rct
Non randomised CT
Cohort study
Case control study
Cross sectional surgery
Case series
Case report
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2
Q

Sensitivity

A

Chance of it being correctly positive
Ie does have the disease and is positive on the test

A/ a+c

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3
Q

Positive predictive value

A

If positive on a test what is the chance they actually are positive for the disease?

A/a+b

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4
Q

Specificity

A

If they don’t have the disease what is the chance the test correctly identifies them as negative?

D/b+d

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5
Q

Negative predictive value

A

If the patient is negative on the test what is the chance they actually are a true negative without the disease

D/c+d

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6
Q

What does CONSORT diagram stand for?

A

Consolidated standards of reporting trials

To improve quality of rct
Patient flow
Includes those lost to follow up

Evidence based minimum set of recommendations for reporting rcts
Standardised way to present report findings

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7
Q

What does PICO stand for?

A

Formulating a question for a study

Patient or problem (population)
Intervention
Comparison
Outcome

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8
Q

Case report

A

Experience of one person
Anecdotal
Prone to chance and bias

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9
Q

Case series

A

Group of people studied
Useful for rare diseases

5 children who presented to EF with abdo epilepsy etc

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10
Q

Cohort study

A

Consequences of exposure to a risk factor
Same group of people followed
One with risk exposure and one without
No one has the disease at start of the trial
Can do retrospectively
Takes long time (usually years)

E.g 500 people who smoke cannabis monitored for 15 years to see if at greater risk of developing schizophrenia

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11
Q

Case control study

A

Compares those with disease and those without
and looks at a risk factor

50 women with hepatitis and 50 women without queries about ear piercing to see if a risk factor

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12
Q

Cross sectional study

A

Surveyed group of people at one point in time
Prevalence of exposure and outcome in a population

E.g population questionnaire examining prevalence of stroke risk factors

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13
Q

RCT

A

Minimises bias
Measures efficacy
Compare two treatments

Kids with fever given either paracetamol or ibuprofen to determine which is better at reducing fever

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14
Q

Endpoints

A

Study should say how endpoint selected e.g morbidity, plaque developed, major CV risk factor

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15
Q

Validity

A

How well does it measure what it was supposed to

Measures variable
Criteria compared to what is know to be valid

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16
Q

Reliability

A

How consistent a test is on repeated measurement

How true is it to true value

Consistency of measurement

Measurement error either:
systematic (dif readings on same machine)
Random error- dif in weight readings

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17
Q

Incidence

A

Rate of occurrence of new cases over a period of time

Measures risk of disease

Number of new cases over time period divided by population size

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18
Q

Prevalence

A

Proportion with disease at a given time

Number with disease divided by population size

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19
Q

Variance

A

Sum of all the differences between the values plus the mean squared

Divided by

Total number of observations - 1

( work out mean
Minus mean from each value
Square each result
Sum of squared results
Divide by number of results -1
20
Q

Standard deviation

A

Degree of spread from the mean

Square root of variance

2 standard deviations above and below =95%

21
Q

Z score

A

Value of an observation into number of standard deviations frommean where it lies

Observation -mean divided by standard deviation

22
Q

95% confidence interval

A

95% of means in the sample like in 1.96 standard error

So 95% of the time the population mean would lie in this range

23
Q

Equation for risk

A

Number of times an event likely to occur

Divided by

Total number of events possible

Ie one in 6 fall ill
Risk = 1/6 = 0.167 or 16.7%

24
Q

Equation for odds

A

Ratio of number of times likely to occur

Divided by number of times not likely to occur

1/5 = 0.2 odds of falling ill

25
Q

Control event rate equation in 2x2

A

C/c+d

26
Q

Experimental event rate

Absolute risk of outcome in experimental group

A

A/a+b

27
Q

Absolute risk reduction

A

CER - EER

If 0.4 shows 40% reduction in risk from control group

28
Q

Relative risk

A

EER/CER

If <1 reduced risk

29
Q

Relative risk reduction

A

CER-EER/ CER

30
Q

Number needed to treat

A

1/ARR

31
Q

Odds ratio

A

A x d
Divided by

B x c

> 1 more likelihood of developing that condition with risk factor

32
Q

P value

A

Usually less than 0.05

Probability of obtaining the result by chance

33
Q

Type 1 error

A

False positive result
Wrongful rejection of null hypothesis
Usually bias, confounders

34
Q

Type 2 error

A

False negative
Wrongful acceptance of null hypothesis

Small sample size

35
Q

Power

A

Probability that a type 2 error will not be made
Ability to detect smallest difference between the two groups
Bigger sample size = more power

0.8 power generally accepted so only 20% chance of type 2 error

Sample size
Alpha value that is as
Variability if decreased this decreases power

36
Q

Chi squared test

A

Compare significance of categorical data
The 2x 2 boxes
Unpaired data

Tests hiv acquisition between iud or dmpa
Ie tests null hypothesis that the two groups are the same

37
Q

Test for normal distribute data

A

T test

Anova

38
Q

Tests for non normal data

A

Wilcoxons rank
Mann Whitney u
Anova
Kruskal Wallis

39
Q

Four stages listed in consort diagram for rct

A

Enrolment
Intervention allocation
Follow up
Analysis of data

40
Q

Forest plot

A

Used to present results of meta analysis

41
Q

Funnel plot

A

Used to identify publication bias

42
Q

Fishers exact test

A

Significance of independent categorical data

Alternative to chi squared test when small sample size

43
Q

Test from funnel plot and in metaanalysis to test for asymmetry

A

Egger test

44
Q

Therapeutic papers

Eg rct looking at high flow oxygen on mortality in copd

A 
Objective
Design
Setting
Population
Method
Intervention
Control
Outcome
Results
Conclusions
45
Q

Diagnostic papers

Eg diagnosis of intersussepyipn by uss in ed

A 
Objective 
Design
Setting
Population
Methods
Test under ix 
Gold standard
Results
Conclusion
46
Q

Meta analysis

A 
Paper identification
Secelection
Funnel plot
Forest plot
Stat analysis (heterogeneity)

MFSRH (8 decks)

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