ARR shows us the difference between two absolute units (8% - 2% = 6%) or absolute difference between two relative units . Reduction - is decreasing by another words. Without vaccine - 8% are ill, with vaccine - 2%. So, we want to know, what is the purpose (the use) of vaccination. ARR answer us for this question. Vaccine decrease the incidence by 6% (ARR).thanks and how do you differentiate between RRR relative reduction and absolute risk reduction i cant understand the explanation of these two given in FA 2014 and uworld ??
Relative risk (RR) - it is a relation (ratio) - 8%/2% or 2%/8% depends on purpose. So, incidence in unvaccinated group is 4 times more than in vaccinated or incidence in vaccinated group is 0,25 of incidence in unvaccinated. Now we get: FA-2014 - RRR= 1 - RR (1 - 0,25 = 0,75), and in wiki - RRR=ARR/incidence in control (without vaccine in this case).
RRR= 0,06/0,08 = 0,75.
May be this will be helpful.