title: Risk factors for knee osteoarthritis in Japanese men: a case-control study.
abstract: Risk of knee osteoarthritis (OA) was assessed in a population-based case-control study of Japanese men. The study covered three health districts in Wakayama and Osaka prefectures, Japan. Subjects were male individuals >or=45 years old diagnosed radiographically with knee OA, and who did not display any established causes of secondary OA. Controls selected randomly from the general population were individually matched to cases for age, sex, and residential district. Subjects were interviewed using structured questionnaires to determine medical history, physical activity, socio-economic factors, and occupation. Interviews were obtained from 37 cases and 37 controls. In univariate analysis, heaviest weight in the past and physical work such as factory, construction, agricultural, or fishery work as the principal occupation significantly raised the risk of male knee OA (P<0.05). Odds ratios (OR) were determined using conditional logistic regression analysis mutually adjusted for potential risk factors using the results of univariate analysis. Heaviest weight in the past (OR 6.01, 95% confidence interval (CI) 1.18-30.5, P<0.05), past knee injury (OR 6.25, 95% CI 1.13-34.5, P<0.05), and physical work as the principal occupation (OR 6.20, 95% CI 1.40-27.5, P<0.05) represented independent factors associated with knee OA after controlling for other risk factors. Physical work is associated with knee OA, demonstrating the influence of working activity on the development of OA. The present study suggests that risk factors for knee OA in men resemble those in women.
authors.affiliation: Department of Joint Disease Research, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan. yoshimuran-ort@h.u-tokyo.ac.jp
authors.forename: Noriko
authors.initials: N
authors.lastname: Yoshimura
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Kinoshita
authors.forename: Noriaki
authors.initials: N
authors.lastname: Hori
authors.forename: Taira
authors.initials: T
authors.lastname: Nishioka
authors.forename: Masahiko
authors.initials: M
authors.lastname: Ryujin
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Mantani
authors.forename: Mariko
authors.initials: M
authors.lastname: Miyake
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Takeshita
authors.forename: Masao
authors.initials: M
authors.lastname: Ichinose
authors.forename: Munehito
authors.initials: M
authors.lastname: Yoshiida
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Oka
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kawaguchi
authors.forename: Kozo
authors.initials: K
authors.lastname: Nakamura
authors.forename: Cyrus
authors.initials: C
authors.lastname: Cooper
mesh_terms: D000368:Aged; D004812:Epidemiologic Methods; D006801:Humans; D007564:Japan; D007718:Knee Injuries / Q000150:complications; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D020370:Osteoarthritis, Knee / Q000209:etiology*; D050177:Overweight