A reassessment of the plateauing relationship between T2 lesion load and disability in MS.
OBJECTIVE
A recent cross-sectional study has shown a plateauing relationship between T2 lesion volume (T2LV) and disability in patients with multiple sclerosis (MS). In this analysis, which also included longitudinal observations, we investigated whether such a relationship is a consequence of the decreased frequency of "inflammatory" events occurring in more disabled patients, rather than reflecting their disability status.


METHODS
The placebo arms of 2 clinical trials were analyzed. One cohort consisted of 548 patients with relapsing-remitting (RR) MS enrolled in a 14-month, randomized, double-blind, placebo-controlled trial of oral glatiramer acetate. The second cohort consisted of 358 patients with secondary progressive (SP) MS still experiencing relapses enrolled in a 3-year, randomized, double-blind, placebo-controlled trial of interferon beta-1b.


RESULTS
At baseline, T2LV was associated with disease duration (p < 0.001), age at MS onset (p < 0.001), and disability (p < 0.001). The relationship between baseline T2LV and Expanded Disability Status Scale (EDSS) was not significantly different between patients with RRMS and SPMS. At a multivariate analysis, T2LV change was associated with the number of on-trial relapses (p < 0.001) and age at MS onset (p = 0.02). The correlations of T2LV change with baseline EDSS and EDSS changes were not significant.


CONCLUSIONS
We showed that the plateauing relationship between T2 lesion volume and disability in multiple sclerosis is not always present and is likely due to the reduced frequency of "inflammatory" events in the most common form of secondary progressive multiple sclerosis.
Sormani
Maria Pia
MP
Biostatistics Unit, Department of Health Sciences (DISSAL), University of Genoa, Milan, Italy.
Rovaris
Marco
M
Comi
Giancarlo
G
Filippi
Massimo
M
D000293:Adolescent; D000328:Adult; D001921:Brain / Q000473:pathology; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D006233:Persons with Disabilities; D004311:Double-Blind Method; D005260:Female; D005500:Follow-Up Studies; D000068717:Glatiramer Acetate; D006801:Humans; D000068576:Interferon beta-1b; D016899:Interferon-beta / Q000627:therapeutic use; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D020528:Multiple Sclerosis, Chronic Progressive / Q000175:diagnosis* / Q000188:drug therapy / Q000473:pathology*; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000175:diagnosis* / Q000188:drug therapy / Q000473:pathology*; D010455:Peptides / Q000627:therapeutic use; D055815:Young Adult
D010455:Peptides; D000068576:Interferon beta-1b; D000068717:Glatiramer Acetate; D016899:Interferon-beta