Vitamin D in SLE: Modest association with disease activity and urine protein/creatinine ratio
Arthritis & Rheumatism Vol. 65 Issue 6
Michelle Petri 1,†,*, Kayode J. Bello 1, Hong Fang 1, Laurence S. Magder 2
Objective: We investigated whether an increase in vitamin D levels in patients with systemic lupus erythematosus was associated with improvement in disease activity.
Methods: 1006 SLE patients were followed over 128 weeks. SLE patients with low levels of 25-hydroxy Vitamin D (<40 ng/mL) were supplemented with 50,000 units Vitamin D2 weekly, with Ca/D3 200 units twice daily. Longitudinal regression models were used to estimate the association between levels of vitamin D and various measures of disease activity.
Results: The SLE patients were 91% female, mean age 49.6, 54% Caucasian, 37% African-American and 8% other ethnicity. For those with low 25-hydroxy Vitamin D (<40 ng/mL), a 20 unit increase in 25-hydroxy Vitamin D was associated with a decrease in mean SELENA-SLEDAI by 0.22 (CI: -0.41, -0.02) (p= 0.032). This corresponded with a 21% decrease in the odds of having a SELENA-SLEDAI higher than 4 (CI: 1%, 37%). Mean urine protein-to-creatinine ratio decreased 2% (CI: -0.03, -0.01) (p=0.009), corresponding to a 15% decrease in the odds of having a ratio of 0.5 or greater (CI: 2%, 27%).
Conclusion: We found that a 20 ng/mL increase in vitamin D was associated with a 21% decrease in the odds of having a high activity score and a 15% decrease in the odds of having clinically important proteinuria. Though these associations were statistically significant, the clinical importance is relatively modest. There was no evidence of additional benefit beyond a level of 40 ng/mL.
© 2013 American College of Rheumatology.