title: Occurrence of radiographic osteoarthritis of the knee and hip among African Americans and whites: a population-based prospective cohort study.
abstract: OBJECTIVE
  To compare the incidence and progression of radiographic osteoarthritis (OA) in the knee and hip among African Americans and whites.
  
  
  METHODS
  Using the joint as the unit of analysis, we analyzed data from the Johnston County Osteoarthritis Project, a population-based prospective cohort study in rural North Carolina. Baseline and followup assessments were 3-13 years apart. Assessments included standard knee and hip radiographs read for Kellgren/Lawrence (K/L) radiographic grade. Weighted analyses controlled for age, sex, body mass index, level of education, and baseline K/L grade; bootstrap methods adjusted for lack of independence between left and right joints. Time-to-event analysis was used to analyze the data.
  
  
  RESULTS
  For radiographic knee OA, being African American had no association with incidence (adjusted hazard ratio [HRadj ] 0.80, 95% confidence interval [95% CI] 0.53-1.22), but had a positive association with progression (HRadj 1.67, 95% CI 1.05-2.67). For radiographic hip OA, African Americans had a significantly lower incidence (HRadj 0.44, 95% CI 0.27-0.71), whereas the association with progression was positive but nonsignificant (HRadj 1.46, 95% CI 0.53-4.01). In sensitivity analyses, the association with hip OA incidence was robust to a wide range of assumptions.
  
  
  CONCLUSIONS
  African Americans are protected against incident hip OA, but may be more susceptible to progressive knee OA.
authors.affiliation: University of British Columbia, Vancouver, and Arthritis Research Centre of Canada, Richmond, British Columbia, Canada. jkopec@arthritisresearch.ca
authors.forename: Jacek A
authors.initials: JA
authors.lastname: Kopec
authors.forename: Eric C
authors.initials: EC
authors.lastname: Sayre
authors.forename: Todd A
authors.initials: TA
authors.lastname: Schwartz
authors.forename: Jordan B
authors.initials: JB
authors.lastname: Renner
authors.forename: Charles G
authors.initials: CG
authors.lastname: Helmick
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Badley
authors.forename: Jolanda
authors.initials: J
authors.lastname: Cibere
authors.forename: Leigh F
authors.initials: LF
authors.lastname: Callahan
authors.forename: Joanne M
authors.initials: JM
authors.lastname: Jordan
mesh_terms: D001741:Black or African American / Q000208:ethnology*; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D018450:Disease Progression; D004198:Disease Susceptibility / Q000208:ethnology; D005260:Female; D005500:Follow-Up Studies; D006621:Hip Joint / Q000000981:diagnostic imaging; D006801:Humans; D015994:Incidence; D007719:Knee Joint / Q000000981:diagnostic imaging; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009657:North Carolina / Q000453:epidemiology; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000208:ethnology*; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000208:ethnology*; D011446:Prospective Studies; D011859:Radiography; D012307:Risk Factors; D044465:White People / Q000208:ethnology*