title: Prevalence of and risk factors for shoulder osteoarthritis in Japanese middle-aged and elderly populations.
abstract: BACKGROUND
  The purpose of this study was to determine the prevalence of shoulder osteoarthritis (OA) in populations older than 40 years and to examine risk factors and the relationship with shoulder function.
  
  
  METHODS
  The respondents in this study consisted of 541 patients who underwent general medical examinations in April 2012 as residents of a single village. The mean age was 65.2 ± 11.0 years (range, 40-89 years), and 341 (63.0%) of the respondents were women. Anteroposterior radiographs of the bilateral shoulder joints were obtained, and the subjects were classified into 3 groups (non-OA, mild OA, and moderate-severe OA) according to the Samilson-Prieto method. With respect to risk factors for shoulder OA, a logistic regression analysis was performed.
  
  
  RESULTS
  Shoulder OA was detected in 17.4% (94 of 541) of the patients. The incidence of OA in both shoulders was 3.1% (17 of 541), and the prevalence of shoulder OA among the respondents 65 years of age or older (20.3%) was significantly higher than that observed among the respondents younger than 65 years (11.1%). The risk of shoulder OA increased according to age, with an odds ratio of 5.59 in the respondents 60 to 69 years of age (P = .027), 11.59 in the respondents 70 to 79 years of age (P = .004), and 10.77 in the respondents 80 years of age and older (P = .004).
  
  
  CONCLUSIONS
  The prevalence of shoulder OA was 17.4%, and the risk factor for shoulder OA was age.
authors.affiliation: Department of Orthopaedic Surgery, Gunma University Graduate School of Medicine, Gunma, Japan. Electronic address: ktsutomu@gunma-u.ac.jp.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Kobayashi
authors.affiliation: Department of Orthopaedic Surgery, Gunma University Graduate School of Medicine, Gunma, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Takagishi
authors.affiliation: Department of Orthopaedic Surgery, Gunma University Graduate School of Medicine, Gunma, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Shitara
authors.affiliation: Department of Orthopaedic Surgery, Gunma University Graduate School of Medicine, Gunma, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Ichinose
authors.affiliation: Department of Orthopaedic Surgery, Gunma University Graduate School of Medicine, Gunma, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Shimoyama
authors.affiliation: Department of Orthopaedic Surgery, Gunma University Graduate School of Medicine, Gunma, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yamamoto
authors.affiliation: Department of Orthopaedic Surgery, National Hospital Organization Takasaki General Medical Center, Takasaki, Japan.
authors.forename: Toshihisa
authors.initials: T
authors.lastname: Osawa
authors.affiliation: Department of Orthopaedic Surgery, Gunma University Graduate School of Medicine, Gunma, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Tajika
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000208:ethnology; D015995:Prevalence; D011859:Radiography; D012307:Risk Factors; D012785:Shoulder Joint
keywords: Shoulder; logistic regression analysis; medical complications; osteoarthritis; prevalence; risk factor