Effect of vitamin D supplementation on progression of knee pain and cartilage volume loss in patients with symptomatic osteoarthritis: a randomized controlled trial

McAlindon T, LaValley M, Schneider E, et al. · JAMA

Null: knee pain declined similarly in both arms (-2.31 vs -1.46 WOMAC points, no significant difference at any timepoint) and MRI cartilage volume loss was identical (P=0.96).

Population

Adults with symptomatic knee OA, 2-year trial

Intervention

Cholecalciferol 2000 IU/day, escalated to keep serum 25(OH)D >36 ng/mL, for 2 years

Comparator

Placebo

Limitations

Modest sample for a structural endpoint; participants not selected for vitamin D deficiency. Randomisation left the vitamin D arm worse off at baseline — more pain, more disability (WOMAC function 22.7 vs 18.5, P=0.04) and less femoral cartilage (P=0.03).