Epidemiology of Multiple System Atrophy in Hokkaido, the Northernmost Island of Japan.

Multiple system atrophy (MSA) is an intractable neurodegenerative disorder that is characterized by various combinations of autonomic failure, cerebellar ataxia, and parkinsonism. We conducted an epidemiological study of MSA using the combined data of a national registry system and a postal survey in Hokkaido, Japan. A postal survey was conducted in 2013 based on national registry data from 2006 to 2011. This survey contained the current status of each patient with MSA that had been collected from attending physicians and recorded into a national registry. Survey items included date, outcomes, primary symptoms, and activities of daily living at the last medical examination. Confirmation data of the diagnosis by a board-certified neurologist was also collected. Based on the national registry data, 1,092 patients with MSA were selected as our target population. The response rate of the postal survey was 81% (885/1,092). After excluding inappropriate responses, 839 patients with MSA were analyzed. Forty-nine percent of the patients were male, and the mean onset age was 62.1 ± 10.4 years. A Kaplan-Meier survival curve revealed that patients with onset symptoms of cerebellar ataxia had a better prognosis than those with onset of parkinsonism or autonomic failure (p < 0.01). Additionally, we found that a higher onset age was associated with poor prognosis. We found that patients with cerebellar ataxia at onset had a better survival prognosis than those with parkinsonism or autonomic failure at onset and that patients with an older age at onset had a worse survival prognosis.