Diagnostic uncertainty during the transition to secondary progressive MS
Diagnosis, monitoring and biomarkers:
Secondary progressive MS (SPMS) is typically defined as deterioration independent of relapses for ≥6 months, following an initial RRMS course. In practice, the definition of SPMS is not always easily applied and a period of diagnostic uncertainty often characterizes the clinical transition from RRMS to SPMS, which can result in a delay in SPMS diagnosis.
This study looked at a group of 123 patients with long term follow-up (≥8 years). Within this group they identified a sub-group who transitioned from RRMS to SPMS during the follow-up period and then characterized this transition period.
The researchers identified 20 subjects as having transitioned from RRMS to SPMS. Fourteen of these 20 subjects (70%) had medical visits with some level of diagnostic uncertainty related to the clinical phenotype. These cases were characterized by possible but not definite progression. The period of uncertainty from the first visit with a suggestion of progression to the visit that was definitely labelled as SPMS was 2.9 ± 0.8 years.
Fourteen of the 20 patients had reached an EDSS of ≥6 by the time of their SPMS diagnosis. The delay in a definite diagnosis of progression may arise due to the subtle nature of early progressive disease as well as caution in applying an SPMS label, in light of the lack of available evidence-based treatments for this condition and patients’ anxieties regarding the prognosis.
A delay in definitive identification of a SPMS phenotype has a number of implications for patient care and research. Patients may remain on therapies for RRMS which have no role in slowing SPMS, which may result in unnecessary side effects and cost.
Early SPMS diagnosis may represent a window of opportunity for intervention, particularly with potential neuroprotective agents.
: Sand IK, Krieger S
: Mult Scler. 2014 Feb 3. [Epub ahead of print]
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