Evidence Based Medicine

Question 1

How is the Positive Likelihood Ratio calculated?

Answer 1

LR+= Sn/(1-Sp)

Question 2

How is the Negative Likelihood Ratio calculated?

Answer 2

LR-=(1-Sn)/Sp

Question 3

2008A Q6

The results of a study undertaken to determine the utility of urinary leukocyte dipstick testing in the diagnosis of urinary tract infections (UTI) in febrile children is shown below.

In this study, the negative predictive value of the leukocyte dipstick test is:
A. 35%
B. 70%
C. 75%
D. 90%
E. 95%

Answer 3

C. 75%

Question 4

What is infant mortality rate?

Answer 4

Number of deaths <12 months age per 1000 live births.

Question 5

NNT

Answer 5

=1/ARR

(absolute risk reduction)

ARR = CER-EER

CER = events in control group/total control group

EER = events in experiment group/total

Question 6

NNH

Answer 6

=1/AR

(Attributable risk)

AR =EER-CER

EER= Experiment event rate

(Events experiments grp/total experiment group)

CER = Control event rate

(Events control group/total control group)