title: Estimating the probability of radiographic osteoarthritis in the older patient with knee pain.
abstract: OBJECTIVE
  To determine whether clinical information can practically rule in or rule out the presence of radiographic osteoarthritis in older adults with knee pain.
  
  
  METHODS
  We conducted a cross-sectional diagnostic study involving 695 adults ages >/=50 years reporting knee pain within the last year identified by postal survey and attending a research clinic. Potential indicators of radiographic osteoarthritis were gathered by self-complete questionnaires, clinical interview, and physical examination. Participants underwent plain radiography (posteroanterior, skyline, and lateral views). Radiographic osteoarthritis was defined as the presence of definite osteophytes in at least 1 joint compartment of the index knee.
  
  
  RESULTS
  Independent predictors of radiographic osteoarthritis were age, sex, body mass index, absence of whole leg pain, traumatic onset, difficulty descending stairs, palpable effusion, fixed-flexion deformity, restricted-flexion range of motion, and crepitus. Using this model, 245 participants had a predicted probability >/=80% (practical rule in), of whom 231 (94%) actually had radiographic osteoarthritis (specificity 93%). Twenty-one participants had a predicted probability <20% (practical rule out), of whom only 2 (10%) had radiographic osteoarthritis (sensitivity 99.6%). The predicted probability of radiographic osteoarthritis for the remaining 429 participants fell into an intermediate category (20-79%).
  
  
  CONCLUSIONS
  Simple clinical information can be used to estimate the probability of radiographic osteoarthritis in individual patients. However, for the majority of community-dwelling older adults with knee pain this method enables the presence of radiographic osteoarthritis to be neither confidently ruled in nor ruled out. Prospective validation and updating of these findings in an independent sample is required.
authors.affiliation: Keele University, Keele, Staffordshire, UK. g.m.peat@cphc.keele.ac.uk
authors.forename: George
authors.initials: G
authors.lastname: Peat
authors.forename: Elaine
authors.initials: E
authors.lastname: Thomas
authors.forename: Rachel
authors.initials: R
authors.lastname: Duncan
authors.forename: Laurence
authors.initials: L
authors.lastname: Wood
authors.forename: Ross
authors.initials: R
authors.lastname: Wilkie
authors.forename: Jonathan
authors.initials: J
authors.lastname: Hill
authors.forename: Elaine M
authors.initials: EM
authors.lastname: Hay
authors.forename: Peter
authors.initials: P
authors.lastname: Croft
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D018771:Arthralgia / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000503:physiopathology; D001175:Arthrography; D015897:Comorbidity; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000503:physiopathology; D010147:Pain Measurement; D011237:Predictive Value of Tests; D012307:Risk Factors; D012720:Severity of Illness Index; D006113:United Kingdom / Q000453:epidemiology