Background/Purpose: In the general population the cardioprotective effects of vitamin D are thought to be due to modulation of inflammatory cytokines.  However, the effects of Vitamin D supplementation on inflammatory biomarkers in various trials have been inconsistent with some trials suggesting a decrease (Am J Clin Nutr 2006:83;754-9) and others finding no effect (Cytokines 2010:50;175-80).  We used the NHANES (National Health and Nutrition Examination Survey) median cut off of Vitamin D at 21.  We then investigated whether vitamin D was associated with or would predict change, in a major inflammatory biomarker, hsCRP, over 2 years in SLE.

Methods: 167 SLE patients (93% female, 63% Caucasian, 32% African-American, mean age 45 yrs) had measurement of hsCRP and 25 hydroxy vitamin D at baseline and at 2 years.  Since distribution of hsCRP was markedly skewed, it was log transformed prior to calculating mean and performing inference.

Results:

There was no difference in hsCRP or Vitamin D levels among patients with different age groups (18-30,31-49,50+) or 25-OH vitamin D levels (<21 and ≥21).  However, Caucasian patients had higher 25 OH vitamin D levels compared to African-Americans (79% vs. 15%, p<0.0001).  At baseline, those with above median Vitamin D had lower hsCRP.  There was a decrease in mean hsCRP in both groups over 2 years, but the difference in change in the two groups was not statistically significant (p=0.78).    

Table : Changes in log_e hsCRP levels, by 25-OH Vitamin D level

Measure	Mean at baseline	Mean after 2 years	Mean Change	p-value for change	Difference in change (95% CI)*	p-value for difference between groups§
					0.08 (-0.26, 0.41)	0.78
Vitamin D <21 (n=78)	1.31	1.04	-0.29	0.011
Vitamin D ≥21 (n=89)	0.66	0.33	-0.37	0.0041

* Difference in change: measure in vitamin D <21 group minus measure in vitamin D ≥21 group.

^§ Adjusted for ethnicity.

 Conclusion: Vitamin D deficiency was associated with higher hsCRP at baseline, but did not predict change of hsCRP over 2 years.  In fact, in contrast to a previous study in the general population (Am J Cardiol 2012:226-30), which showed an increase in hsCRP levels over time with higher vitamin D levels, our study found a reduction in 25-OH vitamin D in this group, as well.  Thus the behavior of vitamin D and hsCRP is different in SLE than in the general population.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/vitamin-d-deficiency-is-associated-with-but-does-not-predict-change-in-hscrp-in-systemic-lupus-erythematosus-sle/