title: Identifying common trajectories of joint space narrowing over two years in knee osteoarthritis.
abstract: OBJECTIVE
  Little is known about the natural history of knee osteoarthritis (OA). We sought to identify common patterns of joint space narrowing (JSN) in well-characterized knee OA patients in the placebo arm of a 2-year international study.
  
  
  METHODS
  We performed secondary data analyses of 622 adults ages 39-80 years in North America (n = 310) and Europe (n = 312) with symptomatic knee OA. Fluoroscopically positioned semiflexed anteroposterior radiographs were obtained at 0, 12, and 24 months. Group-based trajectory modeling was used to identify distinctive groups of individuals with similar trajectories of JSN, taking into account sex, age, and body mass index.
  
  
  RESULTS
  Seven groups were identified. Four exhibited joint space width (JSW) stability over 2 years representing the most common trajectory (71%), which was unrelated to initial JSW. Atypical courses included slow, rapid, and moderate progressors; most had significant JSN at study entry. Slow progressors (20%) had a mean JSN of 0.2 mm over 2 years. Only 2% of the sample demonstrated rapid JSN (2.1 mm), while 7% had JSN of 0.7 mm. Rapid progressors tended to be men, while slow and moderate progressors were older and heavier.
  
  
  CONCLUSIONS
  Most (70%) people with OA demonstrated no significant JSN over 2 years; 20% showed slow progression, 7% had moderate, and 2% had rapid JSN. Progressors tended to have less JSW at study entry and were older and heavier; rapid progressors were more likely to be men. Understanding common patterns of the course of knee OA may offer new opportunities to target those at greatest risk of disability.
authors: McGill University Health Center, Montreal, Quebec, Canada. Susan.bartlett@mcgill.ca
authors: Susan J
authors: SJ
authors: Bartlett
authors: Shari M
authors: SM
authors: Ling
authors: Nancy E
authors: NE
authors: Mayo
authors: Susan C
authors: SC
authors: Scott
authors: Clifton O
authors: CO
authors: Bingham
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D050071:Bone Density Conservation Agents / Q000627:therapeutic use; D004185:Disability Evaluation; D018450:Disease Progression; D012968:Etidronic Acid / Q000031:analogs & derivatives / Q000627:therapeutic use; D005060:Europe; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000187:drug effects; D008297:Male; D008875:Middle Aged; D009656:North America; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging* / Q000188:drug therapy; D011859:Radiography; D000068296:Risedronic Acid; D012720:Severity of Illness Index; D013997:Time Factors
chemical_list: D050071:Bone Density Conservation Agents; D000068296:Risedronic Acid; D012968:Etidronic Acid