1. This study found no difference in reported pain levels among patients with knee osteoarthritis who took wither placebo or 50,000 IU of vitamin D3 per week for 24 months.
2. This study found no difference in tibial cartilage thickness among patients with knee osteoarthritis who took wither placebo or 50,000 IU of vitamin D3 per week for 24 months.
Evidence Rating Level: 2 (Good)
Study Rundown: Osteoarthritis is a common cause of morbidity and disability in the United States. It has been hypothesized that vitamin D may be helpful in individuals with osteoarthritis, but the current evidence is mixed. The Vitamin D Effect on Osteoarthritis (VIDEO) study is a randomized controlled trial to evaluate the effect of vitamin D supplementation on osteoarthritis. Individuals from two sites in Australia between 50 and 79 years of age with symptomatic knee osteoarthritis were randomized to receive 50,000 international units (IU) of Vitamin D3 for 24 months or placebo. These individuals were followed for two primary outcomes: self-reported knee pain, and change in tibial cartilage volume on MRI. After 24 months of follow-up, and based on an intention-to-treat analysis, the study found that there were no significant differences between the groups with respect to self-reported pain or tibial cartilage volume. The major strengths of this study include the rigorous inclusion criteria and the randomized placebo controlled study design. However, it is limited by the fact that all participants are from Australia, possibly limiting generalizability to other parts of the world. Another limitation of this study is the fact that the primary end points were restricted to pain and tibial cartilage volume, which may not reflect functional improvement in individuals taking vitamin D. Ultimately, this study does not support the use of vitamin D3 supplementation in knee osteoarthritis, but longer studies with more participants may be helpful in further evaluating the use of vitamin D3 in osteoarthritis.
In-Depth [randomized controlled trial]: The Vitamin D Effect on Osteoarthritis (VIDEO) study randomized individuals between 50 and 79 years of age with knee osteoarthritis from two centers in Australia to take 50,000 IU of vitamin D3 per week or placebo. A total of 413 individuals were followed for 24 months and WOMAC pain scores and MRI tibial cartilage volume were assessed. At baseline, the WOMAC pain scores between the two groups were no different (difference 3.2, 95%CI -13.5 to 19.8, p = 0.71). The WOMAC pain scores between the two groups were also no different at the end of the 24 month study (difference -10.2, 95%CI -28.8 to 8.4, p = 0.28). There was also no difference between the tibial cartilage volume between the two groups at baseline (p = 0.09) or at the end of the study period (p = 0.013). Finally, there was no difference in the change in tibial cartilage volume between the two groups at the end of the study period (p = 0.11).
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