Clinical and epidemiological features of myasthenia gravis in Chilean population

Abstract

© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd Objective: To provide an estimated prevalence and describe the clinical features of myasthenia gravis (MG) in Chile. Method: We carried out (i) a prevalence study of MG using the capture-recapture method and the hospital register of pyridostigmine prescription in South-East Santiago (ii) a nationwide survey of MG patients. Results: Prevalence in adults in South-East Santiago was estimated to be 8.36/100 000 inhabitants (CI: 95%, 7.98-8.80). From the nationwide survey, 405 questionnaires were analysed, there was a female/male ratio of 2.2:1. The mean age of onset of symptoms was 38.7 years (range 1-89). The onset was ocular in 46.4%, oculobulbar in 11.6%, bulbar in 8.9%, limbs in 11.6% and generalized in 21.4%. Of the 13.3% of patients who had had a diagnosis of thymoma, only four of these patients were >60 years old at onset. Thymomas were commoner in patients living in mining counties. Patients ≥60 years old at onset of