Eur J Neurol. 2017 Oct 11. doi: 10.1111/ene.13476. [Epub ahead of print]
Low clinical conversion rate in clinically isolated syndrome (CIS) patients – diagnostic benefit of McDonald 2010 criteria?
Rosenkranz SC, Kaulen B, Neuhaus A, Siemonsen S, Köpke S, Daumer M, Stellmann JP, Heesen C.
New diagnostic criteria of Multiple Sclerosis (MS) increase the number of patients being diagnosed with MS while a substantial part might not convert to clinically definite MS (CDMS).
Diagnostic accuracy of the McDonald 2005 and 2010 criteria for conversion to CDMS was evaluated in an unselected cohort of patients in whom a MS diagnostic workup was decided.
We analyzed clinical, MRI and CSF data in all patients who presented with symptoms suspicious for MS at the University based MS outpatient clinic between 2006 and 2010 (n=165).
Follow-up was available for 131 patients. During the mean follow-up period of 2 years, 19% of patients developed clinically definite multiple sclerosis (CDMS) whereas 64% of the patients fulfilling McDonald2010 criteria did not convert to CDMS.
CONCLUSION: The low clinical conversion rate indicates that new diagnostic criteria may increase the incidence of MS cases with a less active disease course.
If 2016 was the year to end all years, 2017 is surely the year of activists and dissidents. On balance, destabilization is a good thing; I like others feel science has followed the views of the majority for far too long.
“In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual.”
― Galileo Galilei
Recently, I posted on the value of CSF analysis in MS; a procedure, which if we’re not careful may disappear altogether in MS. Rosenkranz et al. in their publication also question whether the science/neurology community were too precipitous in our blind reliance of the MRI diagnostic criteria in suspected MS cases?
There are a number of MRI criteria in practice, they all vary in their sensitivity (ability to correctly identify those with the disease) and specificity (ability to correctly identify those without the disease). But, what is apparent is that through the years the various iterations have improved sensitivity substantially, but at the cost of ever decreasing specificity. Not surprisingly, the authors state that ‘the validity for MRI as a diagnostic and prognostic tool is a matter of ongoing discussion’.
In their study, Rosenkranz et al. identified 131 individuals with initial presentation of demyelination (clinically isolated syndrome, CIS). During the follow-up period of 2 years, 19% developed clinically definite MS based on the Poser criteria (click on the hyperlink of CSF analysis in MS to view this criteria). Conversely, 45% fulfilled the 2010 McDonald criteria (this figure was lower when the 2005 criteria was applied). In short, the 2010 criteria lead to more MS diagnosis at the CIS stage, including those who do not then go onto experience further clinical events!
The catch-22 of this scenario is that we don’t truly know the long term prognosis/outcomes of these individuals. How can we then judge whether there is harm from early treatment or if there are long-term benefits to be had? I’m conflicted in all of this as I am an early treatment advocate and believe in pushing the boundaries.