title: The efficacy of natalizumab in patients with multiple sclerosis according to level of disability: results of an observational study.
abstract: BACKGROUND
  Little is known about how the level of disability at the start of treatment with natalizumab affects its efficacy.
  
  
  OBJECTIVE
  The aim of this study was to investigate the effect of natalizumab on relapses in patients with different levels of baseline disability associated with MS.
  
  
  METHODS
  This single-centre observational study collected demographic data for patients followed prospectively and who were scheduled to start natalizumab therapy due to the presence of disease activity. The annualized relapse rate (ARR) and Kurtzke Expanded Disability Status Scale scores were analysed for the previous year, on starting treatment (baseline) and 1 year after starting therapy.
  
  
  RESULTS
  Seventy-seven patients (mean age: 39.0 years, mean disease duration: 12.4 years) were included. The difference between ARR before and after starting treatment was 0.92 for baseline Expanded Disability Status Scale ≤ 3.5 (p < 0.0005), 0.70 for Expanded Disability Status Scale 4.0-6.0 (p < 0.007) and 0.57 for Expanded Disability Status Scale ≥ 6 (p = 0.386). Expanded Disability Status Scale did not vary during the study. One patient discontinued treatment due to an adverse event and nine patients discontinued due to positive anti-natalizumab antibodies.
  
  
  CONCLUSIONS
  The findings support the efficacy of natalizumab in reducing ARR in the year after starting treatment in patients with baseline Expanded Disability Status Scale ≤ 6.
authors.affiliation: Institute of Clinical Neurosciences, Hospital Regional Universitario Carlos Haya, Málaga, Spain. oscar.fernandez.sspa@juntadeandalucia.es
authors.forename: Oscar
authors.initials: O
authors.lastname: Fernández
authors.forename: Marcos Papais
authors.initials: MP
authors.lastname: Alvarenga
authors.forename: Miguel
authors.initials: M
authors.lastname: Guerrero
authors.forename: Antonio
authors.initials: A
authors.lastname: León
authors.forename: Ana
authors.initials: A
authors.lastname: Alonso
authors.forename: Jose Carlos
authors.initials: JC
authors.lastname: López-Madrona
authors.forename: Laura
authors.initials: L
authors.lastname: Leyva
authors.forename: Begoña
authors.initials: B
authors.lastname: Oliver
authors.forename: Enrique
authors.initials: E
authors.lastname: de Ramón
authors.forename: Gloria
authors.initials: G
authors.lastname: Luque
authors.forename: Victoria
authors.initials: V
authors.lastname: Fernández
mesh_terms: D000328:Adult; D000911:Antibodies, Monoclonal / Q000009:adverse effects / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D007155:Immunologic Factors / Q000009:adverse effects / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D020528:Multiple Sclerosis, Chronic Progressive / Q000175:diagnosis / Q000188:drug therapy*; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000175:diagnosis / Q000188:drug therapy*; D000069442:Natalizumab; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012008:Recurrence; D012720:Severity of Illness Index; D013030:Spain; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D007155:Immunologic Factors; D000069442:Natalizumab