ASSOCIATION OF WEIGHT CHANGE WITH CHANGES IN KNEE PAIN AND FUNCTION IN PERSONS WITH SYMPTOMATIC KNEE OSTEOARTHRITIS: DATA FROM THE OSTEOARTHRITIS INITIATIVE

Background: Overweight is a major risk factor for the development and progression of knee osteoarthritis (OA). Weight loss has been associated with improvement in self-reported pain and function and is recommended by EULAR as part of the management of knee OA.Objectives: To examine the association between weight change and change in self-reported symptoms and function and physical performance in adults with symptomatic knee OA over one year.Methods: Data for these analyses were obtained from the Osteoarthritis Initiative (OAI) database, which is available for public access at "http://www.oai.ucsf.edu/." Specifically, we examined data from the baseline and 12-month follow-up visit for 711 of 1388 subjects with symptomatic radiographic knee OA enrolled in the Progression subcohort; data for the remaining 677 subjects have not been released yet for public use. All subjects completed the Western Ontario McMaster Osteoarthritis Index (WOMAC) and Knee Osteoarthritis Outcome Scale (KOOS) at both visits. Weight was measured at both visits with a balance beam scale; height was measured at the baseline visit with a Stadiometer. Physical performance was measured with a timed 20-meter walk. Names and dosage of medications were recorded at clinic visits by trained personnel. Correlations between change in weight and change in symptoms were examined in unadjusted and multiple variable adjusted models using generalized estimating equations to control for the correlation between knees in subjects with more than one involved knee at baseline.Results: At entry, the 711 subjects had a mean (SD) age of 61.8 (9.4) years; 422 (59.4%) were women and 582 (81.9%) were white. The mean weight, height and body mass index (BMI) were 85.0 (16.7) kg, 1.68 (0.09) meters and 30.0 (4.9) kg/m, respectively. One-third had bilateral symptomatic knee OA. Over an average follow-up time of 12 months, the mean weight change for all 711 subjects was -0.20 (4.07) kg: mean (SD) weight change was -3.42 (2.6), 0.08 (0.6) and 3.59 (3.2) kg, respectively for the lowest, middle and highest tertile. In unadjusted analyses, the only significant correlation of weight change with symptomatic and functional outcomes was with 20-meter walking speed: R = -0.099, P < 0.01. This correlation remained significant after adjustment for age, gender, race, baseline BMI and use of analgesic and/or antiinflammatory medications at both visits. Correlation Coefficients of Weight Change with Change in Outcomes Outcome Unadjusted Multiple variable adjusted WOMAC Pain Scale -0.031 -0.032 WOMAC Function Scale 0.033 0.029 WOMAC Total 0.021 0.019 KOOS Symptom Scale 0.004 0.003 KOOS Pain Scale -0.001 0.002 KOOS Function Scale -0.026 -0.029 KOOS Quality of Life -0.025 -0.023 20 meter Walking Speed -0.099* -0.098* *P < 0.01. Conclusion: These data, from a subset of participants with symptomatic radiographic knee OA in the OAI, demonstrate a significant inverse correlation between weight change and change in walking speed, a measure of physical performance, but fail to demonstrate significant correlations between weight change and changes in symptoms and self-reported function over 12 months. Further analyses will include data from the entire Progression Subcohort with longer follow-up and also explore the possible relationship between weight change and change in structural outcomes assessed with fixed flexion knee radiographs and magnetic resonance imaging.References: Additional documentation describing the design and methods of the Osteoarthritis Initiative is available on the OAI Online website ("http://www.oai.ucsf.edu/").Citation: Ann Rheum Dis, volume 67, supplement II, year 2008, page 95Session: Abstract Session: Is treatment of OA feasable?