The effect of vitamin D supplementation on knee osteoarthritis, the VIDEO study: a randomised controlled trial

Arden NK, Cro S, Sheard S, et al. · Osteoarthritis and Cartilage

Null: no difference in the rate of medial joint space narrowing over 3 years (-0.01 vs -0.08 mm/year; difference 0.08 mm/year, 95% CI -0.14 to 0.29, P=0.49); no meaningful symptom benefit.

Population

UK adults with radiographic knee OA, 3-year trial (VIDEO study)

Intervention

Cholecalciferol 800 IU/day for 3 years

Comparator

Placebo

Limitations

Radiographic joint-space narrowing is an insensitive outcome, and 39% of index-knee readings were missing at three years, though sensitivity analyses matched the primary result. The trial itself addresses the two usual objections: half of both arms were deficient at entry, the joint-space result was no different in them, and 800 IU/day raised serum vitamin D by almost 10 ug/L and lifted more than 80% of the deficient out of deficiency.