The Kurtzke EDSS rank stability increases 4 years after the onset of multiple sclerosis: results from the MSBase Registry.
BACKGROUND
The Expanded Disability Status Scale (EDSS) is widely used to rate multiple sclerosis (MS) disability, but lack of disease duration information limits utility in assessing severity. EDSS ranking at specific disease durations was used to devise the MS Severity Score, which is gaining popularity for predicting outcomes. As this requires validation in longitudinal cohorts, we aimed to assess the utility of EDSS ranking as a predictor of 5-year outcome in the MSBase Registry.


METHODS
Rank stability of EDSS over time was examined in the MSBase Registry, a large multicentre MS cohort. Scores were ranked for 5-year intervals, and correlation of rank across intervals was assessed using Spearman's rank correlation. EDSS progression outcomes at 10 years were disaggregated by 5-year EDSS scores.


RESULTS
Correlation coefficients for EDSS rank over 5-year intervals increased with MS duration: years 1-6=0.55, years 4-9=0.74, years 7-12=0.80 and years 10-15=0.83. EDSS progression risk at 10 years after onset was highly dependent on EDSS at 5 years; one-point progression risk was greater for EDSS score of >2 than ≤2. Two-point progression was uncommon for EDSS score of <2 and more common at EDSS score of 4.


CONCLUSIONS
EDSS rank stability increases with disease duration, probably due to reduced relapses and less random variation in later disease. After 4 years duration, EDSS rank was highly predictive of EDSS rank 5 years later. Risk of progression by 10 years was highly dependent on EDSS score at 5 years duration. We confirm the utility of EDSS ranking to predict 5-year outcome in individuals 4 years after disease onset.
Department of Neurology, Royal Melbourne Hospital, Victoria, Australia.
Stella
S
Hughes
Timothy
T
Spelman
Maria
M
Trojano
Alessandra
A
Lugaresi
Guillermo
G
Izquierdo
Francois
F
Grand'maison
Pierre
P
Duquette
Marc
M
Girard
Pierre
P
Grammond
Celia
C
Oreja-Guevara
Raymond
R
Hupperts
Cavit
C
Boz
Roberto
R
Bergamaschi
Giorgio
G
Giuliani
Maria Edite
ME
Rio
Jeannette
J
Lechner-Scott
Vincent
V
van Pesch
Gerardo
G
Iuliano
Marcela
M
Fiol
Freek
F
Verheul
Michael
M
Barnett
Mark
M
Slee
Joseph
J
Herbert
Ilya
I
Kister
Norbert
N
Vella
Fraser
F
Moore
Tatjana
T
Petkovska-Boskova
Vahid
V
Shaygannejad
Vilija
V
Jokubaitis
Gavin
G
McDonnell
Stanley
S
Hawkins
Frank
F
Kee
Orla
O
Gray
Helmut
H
Butzkueven
D004185:Disability Evaluation; D018450:Disease Progression; D006801:Humans; D009103:Multiple Sclerosis / Q000473:pathology*; D012042:Registries; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D013997:Time Factors