MISC

Question 1

Mode of action of tramadol

Answer 1

Mu opioid agonist

Serotonin and noradrenaline reuptake inhibition

Question 2

Mode of action of tapentadol

Answer 2

Mu opioid agonist

Noradrenaline reuptake inhibition

Question 3

Which analgesia should be avoided with TCA, SSRI, SNRI, MAOI

Answer 3

Tramadol - risk of serotonin syndrome

Question 4

Do positive/negative predictive values or sensitivity/specificity depend on the prevalence?

Answer 4

Predictive values

Sensitivity = out of everyone who has X, how many people tested positive for X?

Predictive values = out of the people who test positive for X, how many actually have X? (so if X was less common, the predictive value would be lower)

Question 5

How to calculate the likelihood ratio

Answer 5

+LR = sensitivity/(1-specificity)

-LR = (1-sensitivity)/specificity

Question 6

What is the T-test good at testing

Answer 6

T-test is comparing means

So it’s good for continuous variables which are normally distributed

Question 7

What is the Chi-squared test

Answer 7

It tests the null hypothesis that the variables are independent

It’s used for categorical (discrete) data

Data is usually 2 columns and 2 rows

Question 8

What is Fisher’s exact test used for

Answer 8

Also tests the null hypothesis in a 2x2 table

It is used for the same situations as Chi-squared but in studies of smaller sample size

Question 9

Type I error vs Type II error in stats

Answer 9

Type I error - rejecting the null hypothesis when it is correct (the P value is not low enough)

Type II error - do not reject the null hypothesis when it is wrong (insufficient numbers)

Question 10

When is logistic regression used?

How is the likelihood of the outcome predicted?

Answer 10

To predict whether variables have an effect on a binary outcome

Odds ratio is used to predict the likelihood

Question 11

Cross section study

Answer 11

Patient population/sample at 1 time point

Provides association, not cause

Question 12

How are patients selected in cohort study and what kind of diseases is it good for studying

Answer 12

Patient selected based on exposure, followed prospectively

Good for uncommon exposures

Question 13

What is the outcome of a cohort study

Answer 13

Risk ratios

Question 14

How are patients selected for a case-control study and what kind if diseases is it good for studying?

Answer 14

Patients selected on basis of disease

Good for uncommon diseases

Question 15

What is the outcome of a cohort study

Answer 15

Odds ratios

Question 16

How to calculate NNT

Answer 16

1/ARR

Question 17

Commencement of thromboprophylaxis after spinal anaesthesia

Answer 17

6-8 hours post catheter removal

Question 18

What is the difference between categorical/nominal and ordinal data

Answer 18

Ordinal is like categorical but there is a clear order between the categories

Question 19

What is the difference between ANOVA and Chi-squared test

Answer 19

ANOVA is used for testing the mean between multiple populations (like T-test but for multiple groups)

Chi-squared is to test the independence of categorical data

Question 20

What is the difference between Cox proportional-hazards model and Kaplan-Meier curve?

Answer 20

Cox proportional hazards model looks like multiple variables that may affect the outcome

Question 21

cluster RCT

Answer 21

randomisation of groups “e.g. schools, hospitals”

lose statistical power

Question 22

network meta-analysis

Answer 22

also called multi-treatment comparison meta-analysis

best way to assess where there is multiple treatments for 1 condition

Question 23

which group of patients obtain the most benefits (have the lowest NNT) for an intervention

Answer 23

highest risk group

mild diseases need the largest NNT

Question 24

what results markers (e.g. ARD, NNT, RR, RRR) changes depending on the risk group?

Answer 24

ARD and NNT, not RR and RRR

of note NNH does not change based on the risk group because it’s an inherent risk of the intervention