CRITICAL APPRAISAL

Question 1

Primary endpoint

Answer 1

The main result measured at the end of a study to see if a given treatment worked.

Question 2

Secondary endpoint

Answer 2

Other result (s) being measured at different time points of the study to assess impact of intervention

Question 3

Clinical endpoint

Answer 3

Occurrence of a disease, symptom, or sign that constitutes one of the target outcomes of the trial

Question 4

Surrogate endpoint

Answer 4

Measure of effect of treatment that may correlate with a realclinical endpointbut does not have a guaranteed relationship, e.g. laboratory marker

Question 5

Composite endpoint

Answer 5

A composite endpoint combines two primary outcomes together. This may be if patients develop vomiting and/or diarrhoea or something like heart failure and/or death.

Question 6

Risk ratio

Answer 6

Risk ratio (also called relative risk),compares the risk of a health event (disease, injury, risk factor, or death) among one group with the risk among another group.
Study: Cohort studies and RCTs

Interpretation of RR: Critical point is 1. A risk ratio greater than 1.0 indicates a positive association, or increased risk for developing the health outcome in the exposed group. For example, a risk ratio of 1.5 indicates thatthe exposed group has 1.5 times the risk of having the outcome as compared to the unexposed group.

Question 7

Rate ratio

Answer 7

A rate ratiocompares the incidence rates, person-time rates, or mortality rates of two groups. It is interpretated the same way as risk ratios but just applies to rates instead. For example,a ratio of 5 means that the event occurred at 5 times the rate in the exposed group than in the non-exposed group

Question 8

Odds ratio

Answer 8

This is a little bit different. We don’t look at a proportion here with the number with the outcome divided by the total number in that group. Instead we look at those who developed the outcome divided by those who didn’t. Just like if you make up a liquid which is 1 part juice concentrate to 4 parts water: the total denominator of parts is actually 5 but when we represent it as an odds ratio it is 1 part to 4.
Study: case control. (therefore the question is flipped around because we don’t start with a group and see if the outcome develops, we start with the outcome and see if they were exposed or not.)
Interpretation of odds ratio: The odds ratiotells us how much higher the odds of exposure are among case-patients than among controls.

Question 9

Hazard ratio

Answer 9

A measure of how often a particular event happens in one group compared to how often it happens in another group, over time. Different from the other measures of association because RRs and ORs are cumulative over an entire study, using a defined endpoint, while HRs represent instantaneous risk over the study time period, or some subset thereof.

Study: survival analysis

Question 10

What are low baseline risks?

Question 11

Absolute risk reduction (ARR)

Answer 11

Absolute risk reduction (ARR):
Amount by which therapy/intervention reduces risk of bad outcome
Difference in AR between two groups

Question 12

Number needed to treat (NNT)

Answer 12

Number needed to treat (NNT): Number needed to treat in order to prevent one additional bad outcome
NNT =1/ ARR

Question 13

Null hypothesis

Answer 13

There is no difference in outcome estimate between two groups

Question 14

Alternative hypothesis

Answer 14

There is a difference between two groups.