question 9B is asking for a number needed to treat (NNT), which i get is 1 / Absolute risk reduction (ARR). However, the data given is in rate (2.0 per 10,000 person years)- anyone know how to approach this to obtain the risk ratio? thx. confused
Hi Brian,
I had the same question. I looked through the slides and the book and didn't see a reference to this problem. I googled and found some legit websites and articles that converted the person-year time as follows:
2/10,000 person years--> 0.0002/ person year
ARR= 0.0002-0=0.0002
I was going to ask about this in small group, but I found this approach in several locations so I'm going to go with it for the HW.
Sorry I missed this before. I tried to set it to send me an email with new posts, but not working.
If the ARR is expressed as a rate, then the NNT will still be its reciprocal, and it will include the duration of treatment needed. For example, if the ARR is 5% over a 3 year study then it's 5%/3 yr and when you turn it upside down it's 20x 3 years; i.e., treat 20 people for 3 years to prevent 1 event.
Does that help?