Download Sample AKT Questions involving Critical Appraisal

Sample AKT Questions involving Critical Appraisal
RCGP: Questions on Research and Statisitics constitute 10% of the questions in the AKT
13. What are funnel plots primarily used for?
A. Demonstrate the heterogeneity of a meta-analysis
B. Demonstrate the existence of publication bias in meta-analyses
C. Provide a graphical representation of the relative risk results in a
case-control study
D. Provide a graphical representation of the relative risk results in a
cohort study
E. Provide a graphical representation of the probability of a patient
experiencing a particular adverse effect
Funnel plots - show publication bias in meta-analyses
A funnel plot is primarily used to demonstrate the existence of
publication bias in meta-analyses. Funnel plots are usually drawn with
treatment effects on the horizontal axis and study size on the vertical
axis.
Interpretation
• a symmetrical, inverted funnel shape indicates that publication bias
is unlikely
• conversely, an asymmetrical funnel indicates a relationship between
treatment effect and study size. This indicates either publication bias
or a systematic difference between smaller and larger studies (‘small
study effects’
3. A double-blind, randomised, placebo-controlled trial, conducted in primary care, of a
new drug for stroke prevention shows statistical and clinical evidence that the drug is
superior to placebo in preventing stroke. In deciding whether or not to use this new drug,
which one of the following statistics is most useful?
a ) NNK (Number Needed to Know)
b ) NNT (Number Needed to Treat)
c ) RRR (Relative Risk Reduction)
d ) CER (Control Event Rate)
e ) RRI (Relative Risk Increase)
Answer: B
The NNT (Number Needed to Treat) calculates the number of patients a clinician needs
to treat in order to prevent one additional adverse outcome.
4. “The expanding use of qualitative research methodology has allowed us to gain
knowledge about the characteristics, complexities and interrelationships of phenomena
such as an individual’s experiences, emotions, beliefs and motives” (David Silverman,
2004). By applying this methodology in the primary care setting, we can obtain a greater
understanding of the patients’ perspective and use this to improve patient health, the
health care system and health service delivery. Which one of the following terms would
you most associate with Qualitative rather than Quantitative research?
a ) Purposive sampling
b ) Controlled trials
c ) Randomisation
d ) Confidence interval
e ) Double blind
Answer: A
The randomised double blind controlled trial is the gold standard in quantitative research.
Prospective studies can be used in Quantitative and Qualitative studies. Confidence
intervals are used in statistics in relation to numeric data in Quantitative research.
Purposive sampling is a sampling method used in Qualitative Research and is the
selection of the most productive sample to answer the research question.
1. You are reading a research paper regarding a new blood test that can be used to
screen for colorectal cancer. It shows the following data:
Cancer present Cancer absent Total no. of cases
Blood test positive 80
40
120
Blood test negative 20
60
80
Total no. of cases 100
100
200
What is the specificity of this new test?
a ) 20%
b ) 33%
c ) 60%
d ) 66%
e ) 75%
f ) 80%
Answer: C
Specificity is a measure of how well the test identifies those who do not have
disease as not having disease (60%). Sensitivity is a measure of how well the test
identifies those with disease as having disease (80%). The positive predictive
value indicates how many people with a positive result have the disease (66%).
The negative predictive value indicates how many people with a negative result
do not have the disease (75%).
6. A research project looking at the management of moderate hypertension divides its
subjects into two groups. Group A, with 1776 subjects, receives anti-hypertensive
medication. Group B, with 1800 subjects, receives a placebo. After five years the risk of
a stroke in Group A is 12%, while in group B it is 20%. What is the Number Needed to
Treat (NNT) to prevent one extra stroke?
a ) 2.00
b ) 1.25
c ) 8.00
d ) 12.50
e ) 58.00
Anser: D
NNT is the reciprocal of the absolute risk reduction. For patients with moderate
hypertension, receiving placebo treatments, about 20% would be expected to have a
stroke over the next five years. This risk is reduced to 12% with antihypertensive drugs.
This results in an absolute risk reduction of 0.20-0.12=0.08. The reciprocal of this
number is 12.5 - implying that a doctor would need to treat about 12.5 moderately
hypertensive patients for five years before he or she could expect to prevent one extra
stroke.
8. A study is performed looking at the chance of stroke in high-risk patients taking a new
oral antithrombotic drug compared to warfarin. The following results are obtained:
New
drug
Total number of
patients
200
Warfarin 600
Number who had a stroke within a 3 year
period
10
12
What is the relative risk of having a stroke within a 3 year period for patients taking the
new drug compared to warfarin?ia
A.A 3.33ia
B.A 0.66ia
C.A 1.2ia
D.A 2.5ia
E.A Cannot calculate from above dataia
Submit answ er
General advice from previous trainees sitting the AKT:
The stats MCQs were harder than we expected as they covered funnel plots, forest plots
and blobograms. The NNT calculations were also not straight forward.- Also know your
mean, mode and median. A lot of the stats were about data interpretation of graphs.