title: Age-related disability in multiple sclerosis.
abstract: There is evidence that the clinical course of multiple sclerosis is age related. The present study evaluated the relationship between age and rate of disability progression in a large hospital-based cohort of definite cases of multiple sclerosis (n= 1,463). Patients were followed every 6 to 12 months for a total period of observation of 11,387.8 person-years. Expanded Disability Status Scale scores increased significantly with increasing current age and longer duration of disease (p=0.007). Median times to reach Expanded Disability Status Scale scores of 4.0 and 6.0, assessed using an extended Kaplan-Meier method with age as a categorical time-varying covariate, were significantly longer among patients aged 20 to 35 years compared with patients aged 36 to 50 and 51 to 65 years (p < 0.0001). Significant associations were observed between mean Expanded Disability Status Scale scores and age at disease onset, current age, and the interaction of age at disease onset and current age (p < 0.001). Current age had a greater effect (59% of variability in the model) on disease severity than did age at disease onset. Furthermore, a multiplicative effect on Expanded Disability Status Scale score was observed for age at disease onset and current age combined, indicating a faster rate of disease progression in older patients. In conclusion, the results of the current study demonstrate the impact of age on rate of disability progression in multiple sclerosis and suggest that an age-adjusted progression index may be a more relevant criterion for defining differences between multiple sclerosis groups.
authors.affiliation: Department of Neurological and Psychiatric Sciences, University of Bari, Bari, Italy. mtrojano@neurol.uniba.it
authors.forename: Maria
authors.initials: M
authors.lastname: Trojano
authors.forename: Maria
authors.initials: M
authors.lastname: Liguori
authors.forename: Giovanni
authors.initials: G
authors.lastname: Bosco Zimatore
authors.forename: Roberto
authors.initials: R
authors.lastname: Bugarini
authors.forename: Carlo
authors.initials: C
authors.lastname: Avolio
authors.forename: Damiano
authors.initials: D
authors.lastname: Paolicelli
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Giuliani
authors.forename: Francesca
authors.initials: F
authors.lastname: De Robertis
authors.forename: Maria Giovanna
authors.initials: MG
authors.lastname: Marrosu
authors.forename: Paolo
authors.initials: P
authors.lastname: Livrea
mesh_terms: D000328:Adult; D017677:Age Distribution; D017668:Age of Onset; D000368:Aged; D015331:Cohort Studies; D004185:Disability Evaluation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000453:epidemiology* / Q000503:physiopathology*; D015999:Multivariate Analysis