Quote:
Originally Posted by Natalie8
Can someone please explain why Biogen is now stating that the risk of PML is still 1:1000 from 24 to 36 months if only 13,000 people have taken the drug more than 24 months? I got the 13,000 number from an article dated Oct. 23. Haven't 18 of the PML cases been 24 months and over? Thanks!!!!
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You can use statistics to prove/disprove almost anything you want. It all depends on what data you use to obtain your numbers.
People think that if 1000 people take Tysabri and 1 gets PML, then that means the risk is 1:1000. When it comes to statistics, this may not be true at all because one has to work with probability and several factors have to be taken into account to obtain the real risk factor.
Now it may very well be the risk is 1:1000 but the chances are slim that it is because of the many factors that would have to be considered here. But I would guess that Biogen is going to use the number that makes Tysabri as attractive a MS drug as possible.
Harry