Statistics Matter
“The Will Roger’s Phenomenon” and changing TIA definitions
Before 2009, the definition of TIA was based upon TIME.
After 2009, the definition of TIA is based upon a normal MRI.
(regardless if the symptoms have resolved or not).
BENEFIT: There are about 30% of what we used to clinically call “TIA”
that we now know with MRI are actually small strokes. The 30%
is an average of a wide range that runs from 10%-50%
depending upon the study and selection criteria.
The distinction between “transient symptoms with
infarct” (TSWI) and transient symptoms with a normal
MRI is said to be important by many because the patient with
an acute abnormality on the MRI is at higher future risk of
stroke than the patient with a normal MRI. (0f course)
This change in statistics by moving your most severe in a minor category to include as your least severe in a major category (meanwhile no functional difference in therapy occurs) is called the Will Rogers Phenomenon.
Will Rogers who was an Oklahoma boy said, “If you took the dumbest third of Oklahomans and moved’ed to California; you’d raise the average IQ of both places! So, if you put your worst TIA’s and because of finding’s of small stroke found on MRI, are moved over into the “stroke” category— one now hears the claim that we have improved the outcomes of both TIA and CVA in the United States. (At least some of that is due to the Will Rogers’ phenomenon)
HARM: Patients with transient focal symptoms before we have any MRI
report and probably even after we have a normal MRI are
likely to still be called “TIA” . We may forget about the
20% of stroke mimics that will also have a normal MRI. Good
studies show that there is a 30% discordance between what ED
physicians call “TIA” and what neurologists call “TIA” prior to a
MRI report. And this same degree of discordance (30%) exists
between fellowship-trained stroke neurologists! So the idea that
a single individual can know the difference between transient
symptoms with infarct versus “TIA” versus stroke mimics is
hubris! Scores like ABCD2 have NOT significantly improved an
individual’s ability to clinically distinguish a “stroke mimic” from
“TIA” from a TSWI.(1)
The routine charge for the work-up of TIA is likely to skyrocket!
More and more places will push for 24/7 MRI with immediate
reads. This will also lead to more unnecessary MRA of head
and neck (“as long as we are getting an MRI”).
While this may be gratifying diagnostically, it is not clear
that this huge investment in technology, human resources,
cost, and charges will make any difference in treatment!
It is highly likely that whether a patient has a normal or
abnormal MRI (at over $5000- 2015 charge) they will be placed on an
aspirin daily which costs pennies regardless of the MRI result!
More MRIs /MRA in the ED will definitely bog down an already
overwhelmed and backed up ED. Administrators and
hospitalists may argue that a normal ED MRI/MRA could
allow us to send the patient home since they are at such low
risk. But what about the recommended carotid US & echo?
Because you have a normal MRI does not prove it is not TIA
—it just proves there is no infarct.
Here is an idea: For the patient with resolved focal neuro-
logical symptoms, why not skip neuro imaging and just get
carotid ultrasound and send home on aspirin if carotids are
non- surgical? And then schedule outpatient TEE (or a TTE?).
If no primary, have the hospital create a pathway for outpatient
TEE (or TTE?).
**this covers only those patients with completely resolved symptoms, resolving symptoms outside the window or with contraindications, or with symptoms very minor or atypical (pure sensory). This does NOT cover those non-TIA patients who may have a bleed (needs plain CT) or those that may be IV-tPA/intervention candidates (needs CTA perfusion). But this definitely illustrates that a “one-size-fits-all-approach” for every “stroke” is no longer tenable.