High prevalence of myasthenia gravis among rural adult populations.

Abstract

There is no evidence of an increased prevalence of myasthenia gravis (MG) in rural agricultural communities. We conducted a prevalence study to examine the prevalence of MG in populations living in rural versus urban areas. We retrieved the electronic medical records of all members of the Health Maintenance Organization to detect patients who had the diagnosis of MG of the district in the year 2012. Main outcome measured the relative risk (RR) of patients with MG compared with controls. A total of 248 total MG cases were found in the 527,258 individuals in the region, with a male to female ratio of 118 (47.6%) to 130 (52.4%). Two hundred twenty-three of these patients with MG (89.9%) lived in urban settlements, whereas 25 (10.1%) came from rural areas. A borderline RR was found in rural areas of 1.61 (95% confidence interval, 0.98-2.66) for men, and a significantly RR in patients aged 55 years and older (RR = 2.85; 95% confidence interval, 1.68-4.84). There is an increased prevalence of MG among rural male adults. A possible association of MG with agricultural pesticides exposure is discussed.