186. Serum Vitamin D Does Not Influence Rate of Progression of Knee Osteoarthritis Over 10 Years: Results from the Hertfordshire Cohort Study

Abstract

Background: Vitamin D has been associated in observational studies with multiple sclerosis, diabetes, cardiovascular disease, cancers, autoimmunity and allergy. Whether there is a causal link is however not known. In a similar vein, recent studies have provided conflicting results regarding a possible role for vitamin D in the pathophysiology of OA. In particular, its impact on disease progression in patients with established OA is uncertain. We investigated whether vitamin D level predicted the rate of structural progression of OA. Methods: 396 men and women (59.1-70.7 years) from the Hertfordshire Cohort Study underwent knee radiographs in 1999- 2003 and again a mean of 10.3 years later. Tibiofemoral joint K&L score and joint space (medial and lateral) were assessed by an experienced reader at both time points in both the left and right knee. At baseline, 25(OH)vitamin D was assayed using a DiaSorin Liason automated chemiluminescent assay (CoV <15%). Results: The mean (S.D.) age of participants was 64.8(2.7) years. OA progression (an increase in K&L score of ≥1) occurred in 51.4% of knees (395 of 768). In 276 knees, the K&L grade increased by 1, in 109 it increased by 2, and in 10 by 3. There was no difference in geometric mean vitamin D level in those that progressed and those that did not (left knee 43.6 and 42.9 nmol/l, P=0.725; right knee 42.5 and 44.3 nmol/l, P=0.409). Vitamin D levels did not differ by magnitude of change in K&L grade from baseline (0, 1, 2, or 3). There was no evidence of a relationship between vitamin D level and tibiofemoral joint space narrowing in either the medial or lateral compartment. Conclusion: Baseline serum vitamin D was not shown to be associated with rate of OA progression in older men and women. Larger prospective studies are required to confirm these findings.