title: Nationwide hospital-based survey of idiopathic normal pressure hydrocephalus in Japan: Epidemiological and clinical characteristics.
abstract: There have been no nationwide epidemiological studies of idiopathic normal pressure hydrocephalus (iNPH) in Japan. Therefore, a nationwide epidemiologic survey of iNPH was performed to determine the number of cases and clinical characteristics by sex and diagnostic level.
  
  
  
  The first survey examined the numbers of cases that met the diagnostic criteria of iNPH and those who underwent shunt operations in 2012. The second survey gathered patients' details to clarify their clinical background characteristics.
  
  
  
  The estimated number of cases meeting the diagnostic criteria in 2012 was 12,900, with 6,700 undergoing shunt operations. The estimated crude prevalence was 10.2/100,000 persons. The age of onset was in the 70s in more than 50% of both men and women. Significantly higher (p< .05) frequencies of gait impairment in men and cognitive decline in women were observed as initial symptoms. At the time of definitive diagnosis, gait impairment was observed most frequently in patients with definite iNPH (77.7%). Hypertension was the most frequent comorbidity (40.0%), followed by diabetes mellitus (17.8%) and Alzheimer's disease (14.8%). Hypertension was observed more frequently in men, but diabetes was observed more frequently in women (p< .05). An LP shunt was the first-choice (55.1%) treatment of iNPH, followed by a VP shunt (43.2%).
  
  
  
  This study showed that iNPH occurs most frequently in the 70s, gait impairment and cognitive decline are the most frequent initial symptoms in men and women, respectively, and hypertension and diabetes are the most frequent comorbidities in men and women, respectively.
authors.affiliation: Department of Epidemiology for Community Health and Medicine Kyoto Prefectural University of Medicine Kyoto Japan; Department of Neurology Kyoto Prefectural University of Medicine Kyoto Japan.
authors.forename: Nagato
authors.initials: N
authors.lastname: Kuriyama
authors.affiliation: Department of Neurosurgery Juntendo University Graduate School of Medicine Tokyo Japan.
authors.forename: Masakazu
authors.initials: M
authors.lastname: Miyajima
authors.affiliation: Department of Neurosurgery Juntendo University Graduate School of Medicine Tokyo Japan.
authors.forename: Madoka
authors.initials: M
authors.lastname: Nakajima
authors.affiliation: Department of Epidemiology and Environmental Health Juntendo University Graduate School of Medicine Tokyo Japan.
authors.forename: Michiko
authors.initials: M
authors.lastname: Kurosawa
authors.affiliation: Department of Public Health Osaka City University Faculty of Medicine Osaka Japan.
authors.forename: Wakaba
authors.initials: W
authors.lastname: Fukushima
authors.affiliation: Department of Epidemiology for Community Health and Medicine Kyoto Prefectural University of Medicine Kyoto Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Watanabe
authors.affiliation: Department of Epidemiology for Community Health and Medicine Kyoto Prefectural University of Medicine Kyoto Japan.
authors.forename: Etsuko
authors.initials: E
authors.lastname: Ozaki
authors.affiliation: College of Healthcare Management Fukuoka Japan.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Hirota
authors.affiliation: Department of Public Health Hokkaido University Graduate School of Medicine Sapporo Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Tamakoshi
authors.affiliation: Department of Behavioral Neurology and Cognitive Neuroscience Tohoku University Graduate School of Medicine Sendai Japan.
authors.forename: Etsuro
authors.initials: E
authors.lastname: Mori
authors.affiliation: Department of Neurology, Hematology, Metabolism, Endocrinology and Diabetology Yamagata University Faculty of Medicine Yamagata Japan.
authors.forename: Takeo
authors.initials: T
authors.lastname: Kato
authors.affiliation: Department of Neurology Kyoto Prefectural University of Medicine Kyoto Japan.
authors.forename: Takahiko
authors.initials: T
authors.lastname: Tokuda
authors.affiliation: Mediscience Planning Inc. Tokyo Japan.
authors.forename: Akinori
authors.initials: A
authors.lastname: Urae
authors.affiliation: Department of Neurosurgery Juntendo University Graduate School of Medicine Tokyo Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Arai
mesh_terms: D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000453:epidemiology*; D060825:Cognitive Dysfunction / Q000453:epidemiology* / Q000209:etiology; D015897:Comorbidity; D003920:Diabetes Mellitus / Q000453:epidemiology*; D005260:Female; D020233:Gait Disorders, Neurologic / Q000453:epidemiology* / Q000209:etiology; D006306:Health Surveys; D006761:Hospitals / Q000706:statistics & numerical data; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000150:complications / Q000453:epidemiology*; D006973:Hypertension / Q000453:epidemiology*; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged
keywords: clinical characteristics; comorbidity; idiopathic normal pressure hydrocephalus; nationwide survey