Treating neuromyelitis optica with azathioprine: 20-year clinical practice

Neuromyelitis optica leads to severe disability. Preventive treatment includes steroids and immunosuppressants, and indications are based on retrospective and observational studies.

We analyzed 158 patients with neuromyelitis optica regarding disease course, prognostic factors, and treatment response to azathioprine, a widely available low-cost drug. Disability accumulation was used as an endpoint to treatment response.

Eight patients with monophasic and 150 with relapsing disease with a median 7 years of disease duration and 4.6 years of follow-up were evaluated. All relapsing patients received preventive treatment, 100 with azathioprine. Only 30% reached Expanded Disability Status Scale (EDSS) 6, and 69% of patients presented no disability accumulation along follow-up. The time under azathioprine and prednisone use were inversely correlated to the hazard of disability accumulation (hazard ratio (HR) = 0.981 and 0.986, respectively; p < 0.01). Each month under azathioprine use reduced disability accumulation by 2.6% (HR = 0.974, p < 0.01), corresponding to an 80% decrease in EDSS progression over 5 years.

We report less disability accumulation than previous series on patients with neuromyelitis optica, two-thirds presenting no disability accumulation along follow-up. Continued azathioprine used from early disease onset was strongly associated to maintenance of neurological function and should be offered as a viable option for low-income scenarios.