Low levels of vitamin D and worsening of knee osteoarthritis: results of two longitudinal studies

Felson DT, Niu J, Clancy M, et al. · Arthritis and Rheumatism

NULL: no association between baseline vitamin D level and radiographic worsening or cartilage loss in either cohort — an early observational check on the vitamin D-OA hypothesis.

Population

Two longitudinal cohorts: Framingham (n=715, ~9-year follow-up) and Boston Osteoarthritis of the Knee Study (n=277, 30 months)

Intervention

Baseline serum 25(OH)D; no intervention

Comparator

Higher vitamin D levels

Limitations

Observational; single baseline measurement; radiographic outcomes are insensitive.