title: Prevalence of radiographic hip osteoarthritis and its association with hip pain in Japanese men and women: the ROAD study.
abstract: OBJECTIVE
  Although hip osteoarthritis (OA) is a major cause of hip pain and disability in elderly people, few epidemiologic studies have been performed. We investigated the prevalence of radiographic hip OA and its association with hip pain in Japanese men and women using a large-scale population of a nationwide cohort study, Research on Osteoarthritis/osteoporosis Against Disability (ROAD).
  
  
  METHODS
  From the baseline survey of the ROAD study, 2975 participants (1043 men and 1932 women), aged 23-94 years (mean 70.2 years), living in urban, mountainous, and coastal communities were analyzed. The radiographic severity at both hips was determined by the Kellgren/Lawrence (K/L) grading system. Radiographic hip OA was defined as K/L ≥ 2, and severe radiographic hip OA as K/L ≥ 3.
  
  
  RESULTS
  The crude prevalence of radiographic hip OA was 18.2% and 14.3% in men and women, respectively, that of severe radiographic hip OA was 1.34% and 2.54%, and that of symptomatic K/L ≥ 2 OA was 0.29% and 0.99%, respectively. The crude prevalence of hip OA, including severe OA, was not age-dependent in men or women. Male sex was a risk factor for radiographic hip OA, whereas female sex was a risk factor for severe radiographic hip OA and hip pain. Compared with K/L = 0/1, hip pain was significantly associated with K/L ≥ 3, but not with K/L = 2.
  
  
  CONCLUSIONS
  The present cross-sectional study revealed the prevalence of radiographic hip OA and severe hip OA in Japanese men and women. Hip pain was strongly associated with K/L ≥ 3.
authors.affiliation: Department of Joint Disease Research, 22nd Century Medical & Research Center, Faculty of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Iidaka
authors.affiliation: Department of Clinical Motor System Medicine, 22nd Century Medical & Research Center, Faculty of Medicine, The University of Tokyo, Tokyo, Japan. Electronic address: murakis-ort@h.u-tokyo.ac.jp.
authors.forename: S
authors.initials: S
authors.lastname: Muraki
authors.affiliation: National Rehabilitation Center for Persons with Disabilities, Saitama, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Akune
authors.affiliation: Department of Medical Research and Management for Musculoskeletal Pain, 22nd Century Medical & Research Center, Faculty of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Oka
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Kodama
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Tanaka
authors.affiliation: Department of Orthopaedic Surgery, Japan Community Healthcare Organization Tokyo Shinjuku Medical Center, Tokyo, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Kawaguchi
authors.affiliation: National Rehabilitation Center for Persons with Disabilities, Saitama, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Nakamura
authors.affiliation: Department of Joint Disease Research, 22nd Century Medical & Research Center, Faculty of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Yoshimura
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018771:Arthralgia / Q000453:epidemiology*; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006621:Hip Joint; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging / Q000453:epidemiology*; D015995:Prevalence; D011859:Radiography; D012307:Risk Factors; D012720:Severity of Illness Index; D012737:Sex Factors; D055815:Young Adult
keywords: Cross-sectional; Hip; Osteoarthritis; Pain; Prevalence