RESEARCH - Clinical and ultrasonographic predictors of joint replacement for knee OA

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Ann Rheum Dis. Published Online First: 10 May 2009. doi:10.1136/ard.2008.099564

BMJ Publishing Group Ltd & European League Against Rheumatism.

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Extended Report

Clinical and ultrasonographic predictors of joint replacement for knee

osteoarthritis: results from a large, 3 year, prospective EULAR study

P G Conaghan 1, M A D'Agostino 2, M Le Bars 3, G Baron 4, N Schmidely

3, R Wakefield 1, P Ravaud 4, W Grassi 5, E -Mola 6, A So 7, M

Backhaus 8, M Malaise 9, P Emery 1 and M Dougados 10*

1 University of Leeds, United Kingdom

2 UVSQ University, France

3 Bristol Myers-Squibb, France

4 Bichat Hospital and INSERM E0357, University of Paris, France

5 Jesi Hospital, Italy

6 La Paz Hospital, Spain

7 Vaudois Hospital, Switzerland

8 Charite University Hospital, Germany

9 Saint Tiltman Hospital, Belgium

10 Paris-Descartes University, France

Abstract

Objectives: To determine clinical and ultrasonographic predictors of

joint replacement surgery across Europe in primary osteoarthritis (OA)

of the knee.

Methods: This was a 3-year prospective study of a painful OA knee

cohort (from a EULAR-sponsored, multi-center study). All subjects had

clinical evaluation, radiographs and ultrasonography (US) at study

entry. The rate of knee replacement surgery over the 3-year follow-up

period was determined using Kaplan-Meier survival data analyses.

Predictive factors for joint replacement were identified by univariate

Log-rank test then multivariate analysis using a

proportional-hazards regression model. Potential baseline predictors

included demographic, clinical, radiographic and US features.

Results: Of the 600 original patients, 531 (88.5%), mean age 67±10

years, mean disease duration 6.1±6.9 years had follow-up data and were

analysed. During follow-up (median 3yrs; range 0 to 4yrs), knee

replacement was done or required for 94 patients (estimated event rate

of 17.7%). In the multivariate analysis, predictors of joint

replacement were: Kellgren & Lawrence radiographic grade (grade III

vs < III, Hazards Ratio (HR) = 4.08 [95% CI = 2.34-7.12], p < 0.0001);

ultrasonographic knee effusion ( 4 mm versus < 4 mm), HR = 2.63 [95%

CI = 1.70-4.06], p < 0.0001); knee pain intensity on a 0-100 mm VAS (

60 versus <60) HR= 1.81 [95% CI=1.15-2.83], p=0.01); and disease

duration ( 5 years versus <5 yrs), HR= 1.63 [95% CI=1.08-2.47],

p=0.02). Clinically detected effusion and US synovitis were not

associated with joint replacement in the univariate analysis.

Conclusion: Longitudinal evaluation of this OA cohort demonstrated

significant progression to joint replacement. In addition to severity

of radiographic damage and pain, US detected effusion was a predictor

of subsequent joint replacement. Osteoarthritis (OA) of the knee is a

major problem for ageing Western populations (1). A major part of the

economic burden is related to joint replacement surgery (2). It would

be advantageous to have predictors of subsequent joint replacement in

order to prioritise research in these patients, address reversible

risk factors and provide cohorts for evaluating putative

disease-modifying therapies (3). The limited prospective studies on

joint replacement for OA suggest that radiographic severity, pain and

global disease assessments, and willingness to consider surgery are

the strongest predictors of subsequent joint replacement surgery (4,

5). Such research highlights the complexity of joint replacement as an

outcome measure in clinical trials, as patient perceptions of need for

surgery and potential side effects affect willingness to undergo a

procedure, socio-economic features are important and these factors are

reflected in regional and national variations in utilisation of joint

replacement (3, 5).

http://ard.bmj.com/cgi/content/abstract/ard.2008.099564v1?papetoc

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