title: Changes in the ascertainment of multiple sclerosis.
abstract: OBJECTIVE
  With diagnostic criteria alterations, increased MRI availability, and awareness of therapies, temporal changes in incidence and prevalence rates may occur, with an increase in the proportion of mildly affected persons diagnosed with multiple sclerosis (MS). The authors assessed temporal trends in the delay from symptom onset to diagnosis (DONDX), and determined whether the degree of disability at diagnosis differs by year of symptom onset (YONSET), using the NARCOMS Registry.
  
  
  METHODS
  The authors selected US participants with an age at symptom onset of 10 to 60 years, and YONSET > or = 1980 (n = 16,581). The authors divided YONSET into 5-year groups and compared DONDX between groups using multivariate Cox regression. The authors classified participants enrolled within 2 years of diagnosis (n = 5,548) as having mild, moderate, or severe disability using Patient Determined Disease Steps, and assessed the association of disability with YONSET using polytomous logistic regression.
  
  
  RESULTS
  DONDX decreased with later YONSET (r = -0.43, p < 0.0001). This association remained after adjustment for demographic factors in a multivariate Cox model. Later YONSET was associated with increased odds of having mild disability at diagnosis as compared to severe disability (OR = 1.10 per year; 1.09 to 1.11).
  
  
  CONCLUSIONS
  The delay from symptom onset to diagnosis is steadily decreasing in MS. An increasing proportion of patients with MS have mild disability at diagnosis after accounting for confounders. As the effectiveness of therapies is influenced by disease duration, this has implications for comparison of treatment effects in modern clinical trials to earlier study results.
authors.affiliation: Department of Neurology, Cleveland Clinic Foundation, Cleveland, OH 44195, USA. marrier@ccf.org
authors.forename: R A
authors.initials: RA
authors.lastname: Marrie
authors.forename: G
authors.initials: G
authors.lastname: Cutter
authors.forename: T
authors.initials: T
authors.lastname: Tyry
authors.forename: O
authors.initials: O
authors.lastname: Hadjimichael
authors.forename: D
authors.initials: D
authors.lastname: Campagnolo
authors.forename: T
authors.initials: T
authors.lastname: Vollmer
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D017668:Age of Onset; D002675:Child, Preschool; D004185:Disability Evaluation; D018450:Disease Progression; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000175:diagnosis* / Q000453:epidemiology* / Q000503:physiopathology; D015999:Multivariate Analysis; D011237:Predictive Value of Tests; D015995:Prevalence; D011379:Prognosis; D044469:Racial Groups; D012042:Registries; D015983:Selection Bias; D012737:Sex Factors; D013997:Time Factors