Applied epidemiology

Question 1

What is the prevention paradox?

Answer 1

A preventive measure which brings much benefit to the population but little benefit to the individual

i.e All male doctors wear seat belts – 1 life saved for 400 people, 399 have worn their seatbelt and had no benefit.

Question 2

Two approaches for prevention paradox and give examples of each.

Which approach is best to address prevention paradox?

Answer 2

Population approach - dietary salt reduction through legislation/getting everyone to wear seatbelts

High-risk approach - screening for people with high blood pressure and treating them/prescribing statins for at risk patients

High-risk approach best to address prevention paradox

Question 3

Identify and present numerical measures of association in written communication

Answer 3

i.e Absolute risk reduction is _ % reduction vs relative risk

Question 4

Discuss the prevention paradox including using numbers to illustrate the paradox –>
Effectiveness of statins in reducing CVD risk
Relative risk 0.75 (95%CI 0.70-0.81)
Assume absolute risk of CVD for all people
needing statins is 10% within next 10 years
How many of the 4 mil people currently on statins
will be prevented from developing CVD?
What is the NNT?

Answer 4

relative risk = risk ratio

4 mil –> 10% = 400,000

1/4 x 400,000 = 100,000 prevented

NNT = 1/ARR = 1/(0.25x0.10) = 40 people needed to treat to save 1 person from CVD