Myasthenia Gravis. A Retrospective Argentine Hospital-Based Study (P02.206)

OBJECTIVE: To study the epidemiological characteristics of myasthenia gravis (MG) in patients from a General Hospital in Buenos Aires, Argentina. BACKGROUND: MG is a relative uncommon disease, with a prevalence estimated approaching 20/100000 worldwide. Data from Argentina are not available. DESIGN/METHODS: Records of patients with MG, followed up at the Neuroimmunology Unit of the Ramos Mejia Hospital were reviewed. Epidemiological, clinical and immunological features were evaluated. RESULTS: Out of 91 MG patients, 63.7% were female. The mean age of onset was 37.5 and the mean disease duration was 8.9 years. 81.6% (71/87) were acetylcholine receptors antibody (AChr-Ab) positive. 1/7 AChr-Abs negative patients was anti-MuSK positive. 6.9% were diagnosed before age 12, all females. Twenty-eight cases (30.8%) had late-onset MG (LO-MG) (onset age >50). This group was characterized by male predominance (male-to-female ratio 1.8/1), which was accentuated in the subgroup with onset age older than sixty (male-to-female ratio 4.3/1). The first main symptoms were ocular (56%) but only 9.9% persisted as ocular MG. 45.1% (41 patients) MG patients had moderate disease (MGFA III) and 9.9% (9 patients) had myasthenic crisis. In LO-MG, 46.4 % (13/28) presented moderate or severe disease (MFGA III-V) at worst status, compared to 74.6% (47/63) in early onset MG (EO-MG) MG (onset age CONCLUSIONS: MG patients in our population had clinical characteristics similar to others previously reported. However, as particular features, late onset MG seems to have less severe disease, with less frequency of myasthenic crisis and inmunosuppresion requirements. The male predominance, already reported, was greater than expected in the LO group. Disclosure: Dr. Aguirre has nothing to disclose. Dr. Melamud has nothing to disclose. Dr. Casen has nothing to disclose. Dr. Villa has received research support from Novartis and Biogen Idec.