Just read an interesting blog on Tysabri (Natalizumab) and PML. It had some interesting stats. Thank you Multiple Sclerosis Research Blog. This is a great blog and I would suggest you follow it if you have MS. It presents the research - the good, the bad and the otherwise!
115, 400 patients treated with Tysabri worldwide as of 31st March 2013
372 cases of PML while using Tysabri reported worldwide to 4th June 2013
85 patients who developed PML while on Tysabri have died (23%)
287 patients who developed PML while on Tysabri survived (77%)
Overall incidence of PML 3.13 per 1000 patients using Tysabri
Factors increasing risk of PML: JCV positive, previous immunosuppressant use (IS), Tysabri use > 2 years
Previous IS use approximately 3-4 fold greater risk of PML than patients with no previous IS use
Duration of Tysabri use prior to PML diagnosis 8-94 doses (mean 40 months)
Important to be tested for JCV every 6 months
Tysabri reduces relapse rate by 81%
Tysabri reduces disablity progression by 64%
Greater than 1 in 3 patients have no disease progression while on Tysabri
Here is a PML risk flow chart for your perusal...
So for me, I am Anti-JCV anitbody status negative, I have no complicating factors, therefore my risk of PML is 1 in 10, 000. However I have a friend whose Anti-JCV Antibody status is positive, she has no prior IS use and has been using Tysabri for 25-48 months, therefore her risk of developing PML is 1 in 189.
Moral of the story. Research, research research, assess, assess, assess!! You should be speaking in depth with your neurologist about starting or continuing to use Tysabri. Make him or her earn their payment; they are working for you and your health. But don't start from a blank slate, take in some prior knowledge which you have gained from reading and researching. The decision to commence using Tysabri was one I did not take lightly and I am JCV negative. The benefits of using Tysabri are huge, but so are the risks. I don't have any side effects and love Tysabri, but every time I am being infused with it, I am not worrying about my risk of developing PML, because I know where I stand with it. Good luck MSers - put your glasses on and get researching.