title: Quantifying the association of radiographic osteoarthritis in knee or hip joints with other knees or hips: the Johnston County Osteoarthritis Project.
abstract: OBJECTIVE
  To quantify the association of radiographic osteoarthritis (ROA) in one knee or hip joint with other knee or hip joints.
  
  
  METHODS
  We analyzed baseline data from the Johnston County Osteoarthritis Project (n = 3068). We fit 4 models for left/right knee/hip. The Kellgren-Lawrence (KL) radiographic grade severity scale was KL 0/1 (no/questionable ROA), 2 (mild ROA), or 3/4 (moderate/severe ROA). We estimated associations between KL grade in contralateral joints and other joint sites (e.g., worst hip in knee models), adjusting for sex, race/ethnicity (African American/white), age, and measured body mass index, using cumulative odds logistic regression models. Interactions were investigated: race/ethnicity by sex; race/ethnicity and sex by the 2 explanatory variables.
  
  
  RESULTS
  Contralateral joint KL grade was strongly associated with KL grade, with OR ranging from 9.2 (95% CI 7.1, 11.9) to 225.0 (95% CI 83.6, 605.7). In the left knee model, the contralateral joint association was stronger among African Americans than whites, but for the other models the associations by race/ethnicity were identical. Models examining other joint sites showed weaker but mostly statistically significant associations (OR 1.4 to 1.8).
  
  
  CONCLUSIONS
  We found a strong multivariable-adjusted association between KL grades in contralateral knees and hips, and a modest association with the other joint site (e.g., knees vs hips). These results suggest that diagnosis of ROA in 1 large joint may be a marker for risk of multijoint ROA, and warrant interventions to reduce the incidence or severity of ROA at these other joints.
authors.affiliation: Arthritis Research Centre of Canada, 895 West 10th Avenue, Vancouver, British Columbia V5Z 1L7, Canada. esayre@arthritisresearch.ca
authors.forename: Eric C
authors.initials: EC
authors.lastname: Sayre
authors.forename: Joanne M
authors.initials: JM
authors.lastname: Jordan
authors.forename: Jolanda
authors.initials: J
authors.lastname: Cibere
authors.forename: Louise
authors.initials: L
authors.lastname: Murphy
authors.forename: Todd A
authors.initials: TA
authors.lastname: Schwartz
authors.forename: Charles G
authors.initials: CG
authors.lastname: Helmick
authors.forename: Jordan B
authors.initials: JB
authors.lastname: Renner
authors.forename: M Mushfiqur
authors.initials: MM
authors.lastname: Rahman
authors.forename: Jaafar
authors.initials: J
authors.lastname: Aghajanian
authors.forename: Weiqun
authors.initials: W
authors.lastname: Kang
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Badley
authors.forename: Jacek A
authors.initials: JA
authors.lastname: Kopec
mesh_terms: D000368:Aged; D001175:Arthrography; D018450:Disease Progression; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000503:physiopathology; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology; D015995:Prevalence; D011379:Prognosis; D012307:Risk Factors