Background: Based on case series and anecdotal evidence, immunosuppression has been shown to reduce relapse rates and delay disability in Neuromyelitis Optica spectrum disorders (NMOSD) and is currently the mainstay of disease modifying treatment. However, some of the newer immunosuppressive treatments are expensive and may not be readily available in resource-poor countries. Objective: To evaluate the efficacy of azathioprine in the treatment of NMOSD in a cohort of Asian patients. Methods: We retrospectively reviewed all patients with NMOSD treated with azathioprine at the National Neuroscience Institute (NNI), Singapore between May 1991 and May 2010. We compared the annualised relapse rates and disability measured by the Expanded Disability Status Scale (EDSS) before and after treatment with azathioprine. We also reviewed the cost of treatment of the various immunosuppressive treatments for NMOSD available in Singapore. results: Twenty-three patients out of 158 patients with central nervous system (CNS) demyelinating diseases from the NNI Neuroimmunology database and tissue repository fulfilled the inclusion criteria (4 male:19 females; mean age 56.0 years [range 35 to 72]). Seven patients were azathioprine-intolerant (30%) and 16 azathioprine-tolerant (70%). Among azathioprine-tolerant patients, 14 received >= 6 months of treatment and 2 received < 6 months of treatment. An analysis of the 14 azathioprine-tolerant patients who received >= 6 months of treatment was carried out. At a median follow-up of 22.1 months, the median post-treatment annualised relapse rate was lower than the pretreatment rate (0.02 [range, 0.00 to 0.52] vs 0.19 [range 0.036 to 2.14] relapses, p = 0.008). Mean EDSS did not change after treatment with azathioprine (pre-treatment 4.79 [SD 2.31] vs post-treatment 4.79 [SD 2.37], p = 1.00). Azathioprine-intolerant patients discontinued treatment because of liver dysfunction (n = 3), neutropaenia (n = 2) and severe sepsis (n = 2). Conclusions: Azathioprine is well tolerated in 70% of patients initiated on therapy and is effective in decreasing the relapse rates, but not disability in NMOSD. The cost of Azathioprine is low compared to the other immunosuppressive treatments for NMOSD.
Read More: Azathioprine for the treatment of neuromyelitis optica spectrum disorders — old but still effective?