[The most probable clinical diagnosis to the applicants for the intractable disease registration of Parkinson's disease, spinocerebellar degeneration and amyotrophic lateral sclerosis].

Amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD) and spinocerebellar degeneration (SCD) are included in the 45 intractable diseases" acknowledged by the Ministry of Health, Labour and Welfare of Japan. The registration of applicants is based on the attending doctors' diagnosis, and medical costs of registered patients are covered by the government. However, the accuracy of the diagnoses has not been investigated previously. The aim of the present study is to investigate the accuracy of the diagnoses of patients registered as PD, SCD and ALS in Mie prefecture of Japan. The study design was cross-sectional and the survey was carried out using an anonymous questionnaire. We asked the attending doctors the most probable clinical diagnosis in each applicant for PD, SCD or ALS at the annual renewal of application form of the specified diseases by the Ministry. The questionnaires were sent to the 57 neurologists in 20 general hospitals and 2 neurology clinics in Mie prefecture, Japan. The survey was carried out from July to September, 2003. For each disorder (PD, ALS, SCD), the accuracy rates were calculated as the ratio of the number of patients with the most probable diagnosis of the consistent disease to the number of all patients registered each disease. Questionnaires on 678 patients replied from 31 neurologists, 27 of whom were the neurology specialists approved by the Japanese Society of Neurology, were retrieved and analyzed. They covered 41.1% of the total registered PD cases, 45.4% of total SCD cases, and 54.0% of total ALS cases in Mie prefecture. The final clinical diagnosis were made by such specialists in 641 cases (94.5%). The accuracy rate of PD was 97.3% for all degenerative parkinsonisms and 90.2% for idiopathic PD, 96.0% for SCD, and 77.8% for typical ALS and 81.5% for ALS and Kennedy-Alter-Sung syndrome. Although the most probable diagnoses were performed by the attending physicians without verification by other raters, the accuracy rates were excellently high in these diseases, partly because most of the attending physicians were neurology specialists. The relatively low accuracy rate in ALS may be caused partly by the difficulty in differentiating it from spine diseases, neuropathies or myopathies at the early stage of the disease when the patients had been registered, or by inclusion of other motor neuron diseases such as Kennedy-Alter-Sung syndrome.