Background: The efficacy of beta-interferon (IFN-β) treatment in Thai patients with demyelinating diseases has not been reported.
Objectives: To evaluate the efficacy and any adverse drug reactions of IFN-β therapy in Thai patients, for each group of demyelinating diseases.
Methods: We retrospectively reviewed data of Thai patients with multiple sclerosis (MS), neuromyelitis optica (NMO) and NMO spectrum disorders (NMOSDs) who attended the MS Clinic at Siriraj Hospital, Thailand from March 2000 to October 2011. We reviewed those 73 patients who received IFN-β. We evaluated the drug's efficacy over 2 years and any adverse drug reactions among these patients.
Results: Of the 40 MS patients who received IFN-β, 26 adhered to the medication for at least 2 years. In addition, 27 NMO/NMOSDs patients who had been diagnosed with MS were treated as such with IFN-β. In the true MS group, the pre- and post-treatment annualized relapse rates (ARR) were 1.25 and 0.59, respectively, so there was a reduction of 52.8% (p = 0.004). In addition, in 69.2% of the patients, IFN-β also showed beneficial effects by prolonging the time to first relapse to 15.9 months and stabilizing or decreasing progression of the disease. In contrast, no significant benefit was seen in the NMO/NMOSDs group. On the contrary, an increase in EDSS was seen in 53.3 % of them. The most common side effects seen were local skin reactions and flu-like symptoms.
Conclusions: Treatment with IFN-β was effective in reducing both ARR and disability progression in Thai patients with MS. In contrast, we observed that giving IFN-β treatment to NMO/NMOSDs patients may lead to a worsening of symptoms.