@article {Koeckhovenjrheum.150751, author = {Esmee Koeckhoven and Marike van der Leeden and Leo D. Roorda and Natasja M. van Schoor and Paul Lips and Arjan de Zwart and Joost Dekker and Martin van der Esch and Willem F. Lems}, title = {The Association Between Serum 25-hydroxy Vitamin D Level and Upper Leg Strength in Patients with Knee Osteoarthritis: Results of the Amsterdam Osteoarthritis Cohort}, elocation-id = {jrheum.150751}, year = {2016}, doi = {10.3899/jrheum.150751}, publisher = {The Journal of Rheumatology}, abstract = {Objective Vitamin D deficiency, which is common among elderly people, has been linked to muscle weakness. In patients with knee osteoarthritis (OA), the association between muscle strength and serum 25-hydroxy Vitamin D [25(OH)D] level has not been studied comprehensively. The aim of our study was to examine the association between serum 25(OH)D level and muscle strength in patients with knee OA. Methods Data of the Amsterdam Osteoarthritis cohort from 319 participants with knee OA were used in a cross-sectional study. Serum 25(OH)D level (nmol/l) was measured by a competitive electrochemiluminescence method. Muscle strength (nm/kg) of the upper leg was measured isokinetically. Univariable and multivariable linear regression analyses were used to calculate the association between serum 25(OH)D level and muscle strength. Results Serum 25(OH)D level was significantly associated with muscle strength (B = 0.036, 95\% CI 0.017{\textendash}0.054, p \< 0.001), adjusted for season of blood collection. After adding body mass index (BMI) to the model, this association was no longer significant (B = 0.011, 95\% CI {\textendash}0.007 to 0.029, p = 0.214). Alcohol consumption, number of comorbidities, and sex were subsequently added and changed the model slightly. Without BMI, this model showed a significant association between serum 25(OH)D level and muscle strength (B = 0.029, 95\% CI 0.014{\textendash}0.043, p \< 0.001). Conclusion The observed association between a low serum 25(OH)D level and muscle weakness in patients with knee OA is attenuated by BMI. Further studies are needed to explain the associations among Vitamin D level, muscle strength, and adiposity in patients with knee OA.}, issn = {0315-162X}, URL = {https://www.jrheum.org/content/early/2016/05/10/jrheum.150751}, eprint = {https://www.jrheum.org/content/early/2016/05/10/jrheum.150751.full.pdf}, journal = {The Journal of Rheumatology} }