Long-term efficacy, tolerability and retention rate of azathioprine in 103 aquaporin-4 antibody-positive neuromyelitis optica spectrum disorder patients: a multicentre retrospective observational study from the UK

Mult Scler. 2014 Oct;20(11):1533-40. doi: 10.1177/1352458514525870. Epub 2014 Mar 19.


Background: Azathioprine (AZA) is a common immunosuppressive drug used for relapse prevention in neuromyelitis optica (NMO).

Objectives: The objective of this paper is to assess efficacy, tolerability and retention of AZA in a large NMO cohort.

Methods: We conducted a retrospective review of medical records of 103 aquaporin-4 antibody-positive NMO and NMO spectrum disorder (NMOSD) patients treated with AZA.

Results: This is the largest reported cohort of AQP4-Ab positive patients treated with AZA. Eighty-nine per cent (n = 92) had reduction in median annualised relapse rates from 1.5 (IQR 0.6-4.0) to 0 (IQR 0-0.27, p < 0.00005) with treatment. Sixty-one per cent (n = 63) remained relapse free at a median follow-up of 18 months. Neurological function improved or stabilised in 78%. At last follow-up, treatment was discontinued in 46% (n = 47). Of these, 62% (n = 29) were because of side effects, 19% (n = 9) because of death, 15% (n = 7) because of ongoing disease activity, and 2% (n = 1) because of pregnancy. Using Kaplan-Meyer curves, we estimate that 73%, 58%, 47% and 33% of patients will remain on AZA for longer than one, three, five and 10 years, respectively, after initiation of treatment.

Conclusions: AZA is a modestly effective treatment for NMO. However, many patients discontinue AZA over time and this seems to reflect poor tolerability more than lack of efficacy.

Keywords: NMO; Neuromyelitis optica; aquaporin-4; azathioprine; retention; tolerability.

Publication types

  • Multicenter Study
  • Observational Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aquaporin 4 / immunology*
  • Azathioprine / therapeutic use*
  • Female
  • Humans
  • Immunosuppressive Agents / therapeutic use*
  • Male
  • Middle Aged
  • Neuromyelitis Optica / drug therapy*
  • Neuromyelitis Optica / immunology
  • Recurrence
  • Retrospective Studies
  • Time
  • Treatment Outcome
  • United Kingdom


  • AQP4 protein, human
  • Aquaporin 4
  • Immunosuppressive Agents
  • Azathioprine