I wanted to discuss Joan's note on Tysabri and the warnings issued by the drug's creator in a bit more detail.
If you haen't read it yet, here it is Joan's Note
She mentions Dr. Steinman's comment that the patients who were treated with Tysabri had one relapse in 3 years, and those treated with standard disease modifying drugs had 2 relapses in 3 years---he commented that, in his opinion, preventing ONE relapse is not worth the cost of possible PML...
They noted that its effects, while impressive, are in general not much better than what is seen with other available drugs: The risk of relapse dropped from an average of two relapses every three years using other approved multiple sclerosis drugs to one every three years with Tysabri.
“Do you want to expose someone to the risk of death for eliminating one relapse every three years?” said Steinman. “I say no.”
What Dr. Steinman did in that comment is to alert us to the ABSOLUTE NUMBERS related to relapse rates in natalizumab research-- rather than the relative numbers we are usually exposed to.
We public (markets and patients) NEVER see the absolute numbers because they tend not to be impressive. These exist as raw data, which is sequestered by the pharmaceutical company. The doctors and researchers on such projects may even have signed a gag order so that they never reveal such raw absolute numbers (Read Pharmageddon by Healy or Overdosed America by Abrahamson for more info)
Here is a primer on the difference between ABSOLUTE numbers and RELATIVE numbers--and how this data is manipulated to make products sound more efficacious. Hang in there---it's math. But this is really important to understand.
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Consider the risk for blindness in a patient with diabetes over a 5-year period. If the risk for blindness is 2 in 100 (2%) in a group of patients treated conventionally and 1 in 100 (1%) in patients treated intensively, the absolute difference is derived by simply subtracting the two risks:
Expressed as an absolute difference, intensive therapy reduces the 5-year risk for blindness by 1%.
The relative difference is the ratio of the two risks.
Expressed as a relative difference, intensive therapy reduces the risk for blindness by half.
Both expressions have their place. Without any qualification, both statements ("reduced the risk by 1%" and "reduced the risk by 50%") could be construed as representing either an absolute or relative difference. But most important, note the difference in "feel." A statement of "reduced the risk by 1%" does feel like a smaller effect than "reduced the risk by 50%."
primer on absolute vs. relative
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Back to Tysabri. Raw data /absolute numbers are interpreted for us by statistics professionals and other marketers before we ever get to read about the research....and by the time it gets to our doctor and us, it has morphed from a modest sounding "prevents one extra relapse in 3 years" to something like "a 50% reduction in relapses" or even better sounding relative information like "90% reduction in lesion activity on MRI."
While these numbers sound like science has shown some kind of overwhelming efficacy, the truth is that this is the ONLY scientific field where raw data is hidden and other scientists (like your doctor supposedly) have only favorably interpreted pseudo data to refer to.
According to the authors of "Selling Sickness" this is common throughout the pharmaceutical industry and our DOCTORS are the main target of this science massaged and reframed to suit marketers. According to Carl Elliot MD (White Coat, Black Hat) though many physicians consider themselves "scientific" they are actually naive about marketing and believe themselves too smart to be fooled-which makes them especially vulnerable to marketing that is couched in scientfic terms.
Unfortunately it makes risk:benefit calculations impossible for the doctor and the patient to understand--because when they are dealing with a phrase like "50% reduction" --they don't also know that means one relapse.
Dr. Steinman gave us the absolute number of reduced relapses provided by Tysabri, something only he, as a researcher and co-creator of this drug, knew. One less relapse every three years. And then he asked, is it worth the risk of death?
I'd like to ask you, what have you read? Have you been exposed to a report or an article somewhere that made you think Tysabri was incredibly effective? How about something that suggested PML is of little concern because the drug is so effective that PML pales in comparison? Can you link it?
Joan and I think this is an important discussion. Please share this note, and give us your feedback.
Marie
