Vitamin D Levels Are Associated with Expression of SLE, but Not Flare Frequency

Table 1

Characteristics of participant groups.

	Control; ()	SLE; ACR 4+; ()	Difference between groups
	Mean ± SD	Mean ± SD	value
Age (years)	49.8 ± 12.4	47.7 ± 13.5	1.0
Diagnosis (years)		7.7 ± 6.2
Outdoor hours per year	718.2 ± 506	490.5 ± 433	0.99
Body mass index score	25.9 ± 4.8	27.4 ± 5.6	1.0
Makeup (FMSS) days per year	307 ± 227	291 ± 214	0.99
Vitamin D 25(OH)D ng/mL	29.5 ± 8.2	23.1 ± 6.3	0.04
Vitamin D 25(OH)D nmol/L	73.7 ± 20.6	57.8 ± 15.7	0.04
	no. (%)	no. (%)	value
Educational background			0.43
Socioeconomic status			0.48
Above average	10 (24.4)	15 (18.8)
Average	29 (70.7)	56 (70.0)
Below average	2 (4.9)	9 (11.3)
Current smoker	1 (2.4)	6 (7.5)	0.42
Regular sun	28 (68.3)	39 (48.8)	0.05
Use sunscreen	32 (78)	65 (81.3)	0.81
Use immunotherapy medications		67 (83.8)
Use of vitamin D supplements	11 (26.8)	29 (36.3); 0	0.32
Use of hormone supplements	10 (24.4)	30 (37.5)	0.16
Deficient 25(OH)D	6 (14.6)	28 (35.0)	0.02
Insufficient 25(OH)D	19 (46.3)	39 (48.8)	0.85
Abnormal 25(OH)D	25 (61)	67 (83.8)	0.01
Deficient 25(OH)D  with supplements	2 (4.9)	13 (16.3)	0.09
Insufficient 25(OH)D  with supplements	1 (2.4)	15 (18.8)	0.01
Abnormal 25(OH)D  with supplements	3 (7.3)	23 (28.8)	0.01
ANA ≥1 : 80 ratio	17 (41.5)	63 (78.8)	0.00

Vitamin D categories: deficiency (50 nmol/L (≤20 ng/mL)), insufficiency (52.5–72.5 nmol/L (>20.0 ≤ 29 ng/mL)), and abnormal (≤72.5 nmol/L (≤29 ng/mL)) [3].