title: Prevalence of radiographic knee osteoarthritis and its association with knee pain in the elderly of Japanese population-based cohorts: the ROAD study.
abstract: OBJECTIVE
  We investigated the prevalence of radiographic knee osteoarthritis (OA) and knee pain in the Japanese elderly using a large-scale population of a nationwide cohort study, Research on Osteoarthritis Against Disability (ROAD), and examined their association.
  
  
  METHODS
  From the baseline survey of the ROAD study, 2,282 participants > or =60 years (817 men and 1,465 women) living in urban, mountainous and seacoast communities were analyzed. The radiographic severity at both knees was determined by the Kellgren/Lawrence (KL) grading system. KL> or =2 and KL> or =3 knee OA were examined separately to assess osteophytosis and joint space narrowing (JSN).
  
  
  RESULTS
  The prevalence of KL> or =2 OA (47.0% and 70.2% in men and women, respectively) was much higher than that of previous studies in Caucasians, while that of KL> or =3 OA was not much different in men. Age, BMI, female sex and rural residency were risk factors for radiographic knee OA, knee pain and their combination. The prevalence of knee pain was age-dependent in women, but not in men. Knee pain was more strongly associated with KL> or =3 OA than with KL=2, and the association was higher in men than in women. Female sex was a strong risk factor even in the subgroup without radiographic knee OA (KL=0/1).
  
  
  CONCLUSIONS
  The present cross-sectional study revealed a high prevalence of radiographic knee OA in the Japanese elderly. Knee pain was strongly associated with JSN especially in men, while women tended to have knee pain even without radiographic OA.
authors.affiliation: 22nd Century Medical & Research Center, The University of Tokyo, Tokyo, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Muraki
authors.forename: H
authors.initials: H
authors.lastname: Oka
authors.forename: T
authors.initials: T
authors.lastname: Akune
authors.forename: A
authors.initials: A
authors.lastname: Mabuchi
authors.forename: Y
authors.initials: Y
authors.lastname: En-yo
authors.forename: M
authors.initials: M
authors.lastname: Yoshida
authors.forename: A
authors.initials: A
authors.lastname: Saika
authors.forename: T
authors.initials: T
authors.lastname: Suzuki
authors.forename: H
authors.initials: H
authors.lastname: Yoshida
authors.forename: H
authors.initials: H
authors.lastname: Ishibashi
authors.forename: S
authors.initials: S
authors.lastname: Yamamoto
authors.forename: K
authors.initials: K
authors.lastname: Nakamura
authors.forename: H
authors.initials: H
authors.lastname: Kawaguchi
authors.forename: N
authors.initials: N
authors.lastname: Yoshimura
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007564:Japan; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000503:physiopathology*; D010146:Pain / Q000523:psychology; D010147:Pain Measurement / Q000523:psychology*; D015995:Prevalence; D011859:Radiography; D012720:Severity of Illness Index