25-hydroxyvitamin D and cardiovascular risk factors in women with systemic lupus erythematosus

Low serum levels of 25-hydroxyvitamin D (25[OH]D; vitamin D) are associated with a higher frequency of cardiovascular disease and risk factors in the general population. Vitamin D deficiency has also been noted in systemic lupus erythematosus (SLE). The objective of this study was to evaluate the associations of serum 25(OH)D levels with cardiovascular risk factors in women with SLE.

Data collected in 181 women with SLE included demographics, SLE activity and damage assessments, cardiovascular risk factors, medications, and laboratory assessments of inflammatory markers and 25(OH)D levels. Multiple linear and logistic regressions were used to estimate the association of 25(OH)D levels with cardiovascular risk factors.

The mean age and disease duration were 43.2 and 11.9 years, respectively. The mean 25(OH)D level was 27.1 ng/ml and 62.2% had 25(OH)D levels <30 ng/ml. In unadjusted analyses, lower 25(OH)D levels were significantly associated with higher diastolic blood pressure, low-density lipoprotein cholesterol, lipoprotein(a), body mass index (BMI), and fibrinogen levels, as well as self-reported hypertension and diabetes mellitus. Lower 25(OH)D levels were also significantly associated with higher SLE disease activity and damage scores. After adjustment for age, seasonal variation, and race/ethnicity, lower 25(OH)D levels were also significantly related to higher fasting serum glucose. With further adjustment for BMI, associations between 25(OH)D and cardiovascular risk factors were no longer significant.

This study demonstrates that vitamin D levels are low in women with SLE and significant associations exist with selected cardiovascular risk factors, although most of these associations can be explained by BMI.