Vitamin D Deficiency Is Associated with Progression of Knee Osteoarthritis
Fang Fang Zhang
First published October 1, 2014, doi: 10.3945/jn.114.193227
J. Nutr. December 1, 2014 jn.114.193227
Abstract
Background: Knee osteoarthritis (OA) causes functional limitation and disability in the elderly. Vitamin D has biological functions on multiple knee joint structures and can play important roles in the progression of knee OA. The metabolism of vitamin D is regulated by PTH.
Objective: The objective is to investigate whether serum concentrations of 25(OH)D and PTH, individually and jointly, predict the progression of knee OA.
Methods: Serum 25(OH)D and PTH were measured at the 30- or 36-mo visit in 418 participants enrolled in the Osteoarthritis Initiative (OAI) who had ≥1 knee with symptomatic and radiographic knee OA. Progression of knee OA was defined as any increase in the radiographic joint space narrowing (JSN) score between the 24- and 48-mo OAI visits.
Results: The mean concentrations of serum 25(OH)D and PTH were 26.2 μg/L and 54.5 pg/mL, respectively. Approximately 16% of the population had serum 25(OH)D < 15 μg/L. Between the baseline and follow-up visits, 14% progressed in JSN score. Participants with low vitamin D [25(OH)D < 15 μg/L] had >2-fold elevated risk of knee OA progression compared with those with greater vitamin D concentrations (≥15 μg/L; OR: 2.3; 95% CI: 1.1, 4.5). High serum PTH (≥73 pg/mL) was not associated with a significant increase in JSN score. However, participants with both low vitamin D and high PTH had >3-fold increased risk of progression (OR: 3.2; 95%CI: 1.2, 8.4).
Conclusion: Our results suggest that individuals deficient in vitamin D have an increased risk of knee OA progression.