Although some observational studies suggest that vitamin D supplementation is beneficial for knee osteoarthritis (OA), a randomized, placebo-controlled, double-blind study called VIDEO found no benefit for vitamin D supplementation on pain reduction or change on tibial cartilage volume in patients with symptomatic knee OA and low endogenous vitamin D levels.
“Even among study participants with low vitamin D levels, supplementation did not slow cartilage loss or improve WOMAC [Western Ontario and McMaster Universities Arthritis Index]-assessed pain. These data do not support the use of vitamin D in patients with knee OA,” according to the Xingzhong Jin, MD, Menzies Institute for Medical Research, University of Tasmania, Hobart, and colleagues.
The study included 413 patients with symptomatic knee OA and low vitamin D serum levels who were randomly assigned in a 1:1 ratio to oral vitamin D3 supplementation (50,000 IU) or placebo for 2 years.
All participants had symptomatic knee OA according to American College of Rheumatology criteria for ≥6 months prior to enrollment in the study, and pain scores of 20 mm to 80 mm on a 100-mm visual analog scale. Mean age was 63.2 years, and 50% of participants were women. Of those randomized, 340 (82.3%) participants completed the study.
Serum levels of vitamin D significantly increased in the group assigned to supplementation compared with placebo over 2 years (40.6 nmol/L vs 6.7 nmol/L, respectively; P <.001). Annual change of tibial cartilage or WOMAC pain score yielded no significant differences between treatment arms. No significant differences were seen between the 2 groups in changes to tibiofemoral cartilage defects or bone marrow lesions.
A total of 56 and 37 patients in the vitamin D supplementation and placebo groups, respectively, experienced ≥1 adverse events. Four participants in the supplementation group developed hypercalcemia compared with 2 in the placebo group. The study strengths include the randomized controlled design, and restricting enrollment to patients with low vitamin D levels, as they would be the most likely to benefit from vitamin D supplementation. In addition, patients had to fall within a predefined range of knee pain to prevent a ceiling or floor effect in the statistical analysis. Patients with late-stage knee OA were excluded because they would have little cartilage remaining, and it would be hard to demonstrate effectiveness of supplementation.
- Jin X, Jones G, Cicuttini F, et al. Effect of vitamin d supplementation on tibial cartilage volume and knee pain among patients with symptomatic knee osteoarthritis: a randomized clinical trial. JAMA. 2016;315:1005-1013.