Background/Purpose: Vitamin D deficiency has also been associated with different chronic conditions including cardiovascular diseases such as coronary artery disease, cardiac failure and hypertension. In SLE, it may be associated with the interferon gene signature. We investigated whether an increase in vitamin D levels was associated improvement in disease activity and blood pressure in SLE patients.

Methods: 1006 SLE patients were followed in a prospective observational study for 138 weeks (July 2009 – March 2012). Serum 25-hydroxyvitamin D levels were measured at routine clinic visits. Patients with low 25-hydroxyvitamin D levels (<40 ng/mL) were supplemented with 50,000 units Vitamin D₂ weekly, and Ca/D₃200 units twice daily. Data analysis was done using longitudinal regression models with one-slope and two-slope models, controlling for race, age, age squared, sex, prednisone, hydroxychloroquine, and date (SAS Institute Inc. Cary, North Carolina, SAS 9.2).

Results: There were a total of 5935 visits with serum 25-hydroxyvitamin D measurements from 1006 different SLE patients.  They were 91% female, mean age was 49.6 (SD = 13.2), 54% Caucasian, 37% African-American and 8% other ethnicity. The number of visits per patient ranged from 1 to 16.  110 (11% had 1 visit, 313 (31%) had 2-5 visits, 517 (51%) had 6-9 visits, and 65 (6%) had 10-16 visits.

Table. Difference in mean disease measure per 20 ng/mL increase in vitamin D based on longitudinal regression models with one or two slopes.

Disease Measure	One-slope Model		Model allowing slope to differ before and after 40 ng/mL
	Slope1 (95% CI)	P-value	Slope1 over range of 0-40 ng/mL (95% CI)	P-value	Slope1 over range of 40+ ng/mL (95% CI)	P-value
Physician Global Assessment	-0.01 (-0.03, 0.01)	0.21	-0.04 (-0.08, -0.01)	0.026	0.01 (-0.02, 0.04)	0.68
SLEDAI-SLEDAI	-0.02 (-0.11, 0.07)	0.65	-0.22 (-0.41, -0.02)	0.032	0.12 (-0.01, 0.24)	0.065
Systolic BP	-2.13 (-2.79, -1.48)	<0.0001	-3.91 (-5.21, -2.63)	<0.0001	-0.86 (-1.73, 0.02)	0.055
Log Urine Protein/Creatinine	-0.02 (-0.03, -0.01)	<0.0001	-0.04 (-0.05, -0.02)	0.0004	-0.01 (-0.01, 0.00)	0.24
Log HSCRP	-0.02 (-0.09, 0.06)	0.64	-0.06 (-0.20, 0.09)	0.45	0.02 (-0.12, 0.15)	0.82

¹Slopes are interpretable as difference in mean level of disease per 20ng/mL increase in vitamin D.

There was significant improvement in both the PGA and SELENA-SLEDAI in those with low vitamin D (<40ng/mL), when vitamin D was increased by 20 ng/mL. There was also improvement in systolic blood pressure and urine protein/creatinine.

Conclusion: After a long follow-up in this SLE Cohort, there was statistically significant improvement in disease activity in those with low vitamin D levels, who increased their vitamin D levels. We also found significant improvement in both systolic blood pressure and urine protein/creatinine with increase in vitamin D. This analysis suggests vitamin D supplementation in SLE patients with low vitamin D levels may have beneficial effects on disease activity and on blood pressure, one of the major predictors of accelerated atherosclerosis in SLE.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/increase-in-vitamin-d-improves-disease-activity-and-systolic-blood-pressure-in-systemic-lupus-erythematosus/