Background/Purpose:

Obesity is a risk factor for the development and progression of knee osteoarthritis (OA) and weight loss is recommended as part of the management of patients with knee OA. We tested the hypothesis that weight loss is associated with structural progression, as measured by the rate of decline in joint space width (JSW), in subjects with radiographic knee OA.

Methods:

Data for this analysis were obtained from the Osteoarthritis Initiative (OAI) public access database (http://www.oai.ucsf.edu). At each visit, subjects completed an extensive battery of questionnaires; weight was measured with a balance beam scale; and fixed flexion, weight-bearing PA radiographs of both knees were obtained using a standard protocol and the Synaflexer platform. We examined data from the baseline, 12-, 24-, 36- and 48-month follow-up visits for subjects with radiographic knee OA. Medial compartment JSW was determined using digitized images and a software tool; all images from a subject were analyzed together blinded to time sequence (see http://oai.epi-ucsf.org/datarelease/SASDocs/kXR_QJSW_Duryea_descrip.pdf for documentation). Mean change in both minimum (mJSW) and JSW0.25 were examined using multiple variable random effects (random slope and random intercept) models including weight, age, WOMAC pain score and use of analgesic and/or anti-inflammatory medications at each visit along with sex, race/ethnicity, and study site from baseline.

Results:

Data from 2683 subjects with radiographic OA in one or both knees (Kellgren-Lawrence grade >=2 on baseline radiograph), with measurement of mJSW and JSW0.25 at one or more time points (median = 3) were included in the analysis. If both knees were affected by radiographic OA, data for the right knee were arbitrarily used in the analysis. Mean (SD) age was 62.1 (9.1) years, weight was 83.9 (16.0) kg, mJSW was 3.97 (1.46) mm and JSW0.25 was 5.36 (1.54) mm at baseline. The mean rate of decline in JSW was more rapid for JSW0.25 than mJSW (0.110 [0.0055] mm vs. 0.088 [0.0055] mm; difference = 0.021 mm/year [95% CI 0.006, 0.037], P = 0.006). Heavier weight was significantly associated with narrower joint space at both mJSW and JSW0.25 at all visits (P < 0.0001). There was a significant inverse association between change in weight and change in both mJSW and JSW0,25 in the multiple variable adjusted models such that subjects with a decline in weight over time had a smaller adjusted rate of decline in both mJSW and JSW0.25 that those who had an increase in weight.  The rate of decline in JSW per unit change in weight did not differ, however, for JSW0.25 and mJSW. Sensitivity analyses performed after excluding subjects with isolated lateral compartment disease (OARSI medial compartment JSN grade = 0 and lateral compartment JSN grade >=1) did not alter the results. Finally, higher WOMAC pain scores and use of analgesic and/or anti-inflammatory medications were both independently associated with the rate of decline in JSW in multiple variable models.

Conclusion:

These data demonstrate an association between weight loss and a reduction in the rate of decline in both mJSW and JSW0.25 in subjects with radiographic knee OA. Weight loss should be recommended as an approach for both symptom and structure modification in knee OA.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/weight-loss-is-associated-with-structure-modification-in-subjects-with-radiographic-osteoarthritis-of-the-knee-data-from-the-osteoarthritis-initiative/