title: Factors associated with functional limitation in stair climbing in female Japanese patients with knee osteoarthritis.
abstract: BACKGROUND
  Osteoarthritis (OA) of the knee is a common form of arthritis, and affects quality of life. We investigated factors associated with functional limitation in stair climbing among female Japanese patients with knee OA. As weight is a known risk factor for knee OA, we focused on body weight at 40 years of age, and examined the association with present weight, past weight, and weight change.
  
  
  METHODS
  Subjects were 360 Japanese women aged 40-92 years who were newly diagnosed with knee OA at 3 university hospitals over a 1-year period. Factors associated with the severity of functional limitation in stair climbing were assessed by calculating odds ratios (OR) using the proportional odds model in logistic regression.
  
  
  RESULTS
  Weight at diagnosis showed a positive association with severe functional limitation in stair climbing; however, a negative association was observed for weight change since age 40. Further analysis indicated that the association with weight at age 40 (highest vs. lowest quartile, OR=2.84, 95% confidence interval: 1.03-7.83, trend p=0.071) is stronger than weight at diagnosis. Other significant characteristics were age (70+ vs. 40-59 years, OR=7.37), previous knee pain and/or swelling 12 years or more before diagnosis (OR=2.67), and physical work (OR=1.94). In addition, higher parity was found to be a negatively associated factor (for tripara or more, OR=0.41).
  
  
  CONCLUSIONS
  This study identified factors, such as heavy weight at age 40 and physical labor, which are potentially useful for preventing severe functional limitation for female knee OA patients. In addition, higher parity was associated with milder stair climbing limitation.
authors.affiliation: Department of Public Health, Osaka City University Faculty of Medicine, Japan. kyou@med-osaka-cu.ac.jp
authors.forename: Kyoko
authors.initials: K
authors.lastname: Kondo
authors.forename: Takashi
authors.initials: T
authors.lastname: Tanaka
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Hirota
authors.forename: Hideya
authors.initials: H
authors.lastname: Kawamura
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Miura
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Sugioka
authors.forename: Hajime
authors.initials: H
authors.lastname: Inoue
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kurosaka
authors.forename: Terumi
authors.initials: T
authors.lastname: Yamashita
authors.forename: Kumiko
authors.initials: K
authors.lastname: Shirata
authors.forename: Yukihide
authors.initials: Y
authors.lastname: Iwamoto
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001835:Body Weight; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D007564:Japan; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000145:classification* / Q000209:etiology; D010298:Parity; D011247:Pregnancy; D012720:Severity of Illness Index