Association between serum vitamin D deficiency and knee osteoarthritis

Abstract

Background: Insufficient levels of serum 25-hydroxyvitamin D (25-OHD) influence the knee joint cartilage and lead to development and progression of knee osteoarthritis (OA). The purpose of this study was to determine the status of serum 25-OHD levels in patients with knee OA compared with controls.

Methods: A total of 148 patients with knee OA and 150 controls were studied. Serum 25-OHD was measured by the ELISA method and concentrations <20 ng/ml were considered as deficient levels. Mann-Whitney U test was used for comparisons of means and logistic regression analysis with calculation of odds ratio (OR) was applied to determine association.

Results: The mean ages of patients and controls were 60.2 ± 12.9 and 60.1 ± 10.2 years, respectively (P = 0.23). In the entire population the mean serum 25-OHD in OA patients was not significantly lower than controls (P = 0.28), but in subgroup analysis the mean 25-OHD in OA patients aged <60 years was significantly lower than controls (23.8 ± 18.8 vs. 34.5. ± 29.6 ng/ml, P = 0.01). In this age group knee OA was significantly associated with serum 25-OHD deficiency which remained significant after adjusting for age and sex (adjusted OR = 2.26, 95% CI 1.15-4.4, P = 0.018). A greater association was observed in patients aged < 55 years (OR = 2.63, 95% CI 1.16-5.95, P = 0.01); whereas the association between OA and serum 25-OHD deficiency in patients aged ≥60 years did not reach a significant level.

Conclusion: These findings indicate a significant association between serum 25-OHD deficiency and knee OA in patients aged < 60 years and suggest serum 25-OHD measurement in any patient with symptoms suggestive of knee OA particularly at the initial stage of disease.