GS Interpreting Information

Question 1

Event rate?

Answer 1

the number of people experiencing an event as a proportion of the number of people in the population

Question 2

Relative risk reduction?

Answer 2

the difference in event rates between 2 groups, expressed as a proportion of the event rate in the untreated group; usually constant across populations with different risks

Question 3

Absolute risk reduction?

Answer 3

the arithmetic difference between 2 event rates; varies with the underlying risk of an event in the individual patient

i.e. intervention- no intervention

Question 4

Effect of low event rate on RRR and ARR?

Answer 4

Low event rate =
Lower ARR
Constant RRR

Question 5

Number needed to treat?

Answer 5

NNT: The number of patients who would have to receive the treatment for 1 of them to benefit

Calculated as:

1. 100 / ARR (expressed as a percentage)
2. 1 / ARR (expressed at proportion)

Question 6

Number needed to harm?

Answer 6

The number of patients who would have to receive the treatment for 1 of them to experience an adverse effect

Calculated as:
1/AAR increase

Question 7

Different data types

Answer 7

Numerical: continuous or discrete

Categorical: Ordinal or nominal

Question 8

How is standard deviation (SD) calculated?

Answer 8

Measures variability of the results from the median

Question 9

Percentile of the median?

Answer 9

50th