ROCKVILLE, Md.—Individuals deficient in vitamin D may run an increased risk of knee osteoarthritis (OA) progression. (Journal of Nutrition. 2014, October; Online. DOI: 10.3945/jn.114.193227)
The new study investigated whether serum concentrations of 25(OH)D and PTH, individually and jointly, predict the progression of knee OA.
Knee 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.
Serum 25(OH)D and PTH were measured at the 30- or 36-month visit in 418 participants enrolled in the Osteoarthritis Initiative (OAI) who had at least one 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-month OAI visits.
The mean concentrations of serum 25(OH)D and PTH were 26.2 μg/L and 54.5 pg/mL, respectively. Approximately 16 percent of the population had serum 25(OH)D < 15 g/L. Between the baseline and follow-up visits, 14 percent 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 percent 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 percent CI: 1.2, 8.4).
Previous research suggests vitamin D deficiency may also increase the risk of developing dementia.