A 3-year cohort study of the natural history of spinocerebellar ataxia type 6 in Japan.

Kenichi Yasui,Gen Sobue,Shigeru Koyano,Hidenao Sasaki,Kenji Nakashima,Eiji Isozaki,Ichiro Yabe,Hidehiro Mizusawa,Kunihiro Yoshida,Shoji Tsuji,Yoshiki Adachi,Setsu Sawai,Masatoyo Nishizawa,Satoshi Kuwabara,Mizuki Ito,Takamichi Hattori,Kazuaki Kanai,Kimihito Arai,Osamu Onodera

doi:10.1186/s13023-014-0118-4

Abstract

BackgroundOnly a few prospective studies have determined which clinical symptoms and factors are associated with the disease severity of spinocerebellar ataxia type 6 (SCA6). A multicenter longitudinal cohort study was conducted to clarify both the natural history of SCA6 in Japan and the factors influencing disease progression.MethodsPatients were consecutively recruited between 2007 and 2008. Scores from the Scale for the Assessment and Rating of Ataxia (SARA) and Barthel Index (BI) were collected prospectively each year. Additionally, data from the Japan intractable diseases research (IDR) registry were collected both retrospectively, from 2003 to 2006, and prospectively, from 2007 to 2010. As a result, we were able to collect 3 years of retrospective data and 4 years of prospective data during the course of 3 yearly visits.ResultsForty-six patients were registered. The follow-up rate of the third year was 93%. The SARA scores worsened significantly each year. Over 3 years, the decline of the SARA scores was 1.33 ± 1.40 points/year. The results of multivariate analysis of the decline of the SARA score were not significant. The IDR scores correlated well with the SARA and BI scores. Kaplan-Meier curves of 7 years of data from the IDR registry illustrated the correlation between the ability to walk and the time course of the disease.ConclusionsInformation regarding the progression of ataxia and the decline in the activities of daily living (ADL) in patients with SCA6 was obtained by a 3-year cohort study and a 7-year IDR study. The decline of the SARA score of patients with SCA6 was 1.33 ± 1.40 points/year. The results elucidate the natural history of SCA6, factors influencing disease severity, and utility of data from the IDR registry of Japan.

Highlights

A few prospective studies have determined which clinical symptoms and factors are associated with the disease severity of spinocerebellar ataxia type 6 (SCA6)
The spinocerebellar ataxias (SCAs) are neurodegenerative diseases characterized by oculomotor disturbances, dysarthria, limb and truncal ataxia, gait disturbances, and additional variable symptoms [1]
Numerous studies have described the clinical manifestations of the Spinocerebellar ataxia (SCA) [2,3,4], very few prospective studies have examined which clinical symptoms and factors are associated with disease severity

Summary

Introduction

A few prospective studies have determined which clinical symptoms and factors are associated with the disease severity of spinocerebellar ataxia type 6 (SCA6). A multicenter longitudinal cohort study was conducted to clarify both the natural history of SCA6 in Japan and the factors influencing disease progression. Numerous studies have described the clinical manifestations of the SCAs [2,3,4], very few prospective studies have examined which clinical symptoms and factors are associated with disease severity. A 2-year follow-up study of EUROSCA used several scales, including the Scale for the Assessment and Rating of Ataxia (SARA), to describe disease progression and identify factors that affected this process [8]. We designed a multicenter longitudinal cohort study of the natural history of SCA6 in Japan. SCA6 was selected because of the high prevalence of patients with this disease in Japan

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