Vitamin K and D Status in Patients with Knee Osteoarthritis: An Analytical Cross-sectional Study.

Knee osteoarthritis (OA) is the most common form of arthritis and it has been known as the main factor of lower limb disability. The aim of the study is evaluating the level of vitamin K and D status as well as determining cut-off point of these vitamins for predicting knee OA and also pain severity in these patients. In this analytical cross-sectional study, participation included knee OA patients and individuals without it who referred to Fasa Osteoarthritis Clinic, Iran. OA was diagnosed according to criteria based on Kellgren and Lawrence rating and the WOMAC score was used for pain evaluation. Data analysis was performed in SPSS version 18 (P> 0.05). In our study, 150 knee OA patients and 300 individuals without it, were participated. The mean of vitamin K and D in OA patients was significantly lower than the group without it (P<0.001). Furthermore, logistic regression showed that after adjustment, each unit decrease in vitamin D and K level leads to an increase the odds ratio of OA to 0.67 and 0.002 times respectively. In receiver operator characteristic (ROC) curve analysis, the cutoff-point for vitamin D and K was determined 12.68 and 0.87 nmol/L respectively. We also observed that although with a decreased level of two vitamins, the score of pain significantly increases, the only effective factors in pain score were disease status. These findings suggest that the deficiency of vitamin K and D is likely associated with a higher risk of OA.