Question

1. A randomized controlled trial concludes that 73% of subjects with a serious disease received no treatment died over a 10 year period while 47% of subjects assigned to treatment A died during that period. The results were statistically significant. How many patients over a 10 year period would you need to treat to prevent one death, on average, from this disease? Show all your work.

Answer 1

Answer-

Let the total number be 100.

So, those who did not received any treatment died in 10 years=73% or 73 persons.

That means 27% received the treatment A.

Out of that 47% died.

i.e. 47*27/100= 12.69 or rounding off to 13 persons.

Hence, persons survived in 10 years= 27-13= 14 subjects.

Now, if we increase the number of persons treated and the death % remains the same, so, to prevent 1 death, we should treat 29 patients with treatment A.

So, untreated will be 71 subjects, who will eventually die.

And, 47*29/100= 13.63 or rounding off to 14 subjects.

That means 14 subjects out of 29 will die after receiving the treatment.

So, number of persons survived= 29-14=15 persons.

Hence, one death can be prevented if we treated 29% of the subjects with treatment A from all the diseased subjects.