Does Serum Vitamin D Concentration Modify the Association Between Arthritis and Cardiovascular Diseases in Both Sexes?

Abstract

Background: The scientific literature shows an association between inflammatory arthritis and cardiovascular diseases (CVD) with inflammation being a shared characteristic between the two types of diseases. Among patients with arthritis, it is possible that the protective factors against inflammation, such as vitamin D, are also protective factors against the development of CVD. This effect may be different according to sex.Objective: To evaluate the impact of serum vitamin D concentration on the association between arthritis and CVD separately among men and women (effect modification of vitamin D and sex).Methods: Data came from a large representative sample of the US population: the National Health and Nutrition Examination Survey (NHANES) 2005-2006, which included 3406 adults aged between 20 and 69 years. Measurements of arthritis (primary independent variable) and CVD (dependent variable) were taken during face-to-face interviews, while the measurement of serum vitamin D was carried out on blood samples. Multivariate logistic regression analyses were performed in which the combined modifying effect of vitamin D (<20 ng/ml/> 20 ng/ml) and sex was tested, and adjusted for several potentially confounding variables.Results: Arthritis was statistically associated with CVD in both men and women, with <20 ng/ml or >20 ng/ml serum vitamin D. In men, the adjusted ratio of the odds ratios (ROR) comparing the association at <20 ng/ml vitamin D concentration to the association at >20 ng/ml concentration was 0.8 (95% CI 0.5 to 1.5); in women, the adjusted ROR was 0.7 (95% CI 0.3 to 1.5). Conclusions: In this large cross-sectional study, arthritis and CVD were statistically associated, but this association was not modified by sex nor vitamin D concentrations. Vitamin D supplementation is not recommended as part of the management of patients of both sexes suffering from inflammatory arthritis to prevent CVD.