Table 5.

Studies in which vitamin D levels are correlated to CTD autoantibodies in connective tissue diseases (CTDs)

Author	Year	Country	Subjects	Vitamin D (ng/ml)	Positive CTD autoantibodies	P valueh	Reference
Ritterhouse L. et al.	2011	USA	32 SLE, 32 CTRLa	17.3 vs. 17.4^ vs. 29.4^^	ANA	<0.01	[46]
Szodoray P. et al.	2011	Hungary	177 SLE (160 females, 17 males)	<15 vs. 15–30 vs. ≥ 30	anti-dsDNA	0.021	[48]
Costenbader K.H. et al.	2008	Boston, USA	190 SLE	NR	Risk of SLE	NS	[49]
Bonakdar Z.S. et al.	2011	Iran	40 SLEb	25–39.9 vs. 12.5–24.9 vs. <12.5 nmol/l	anti-dsDNA	<0.001	[50]
Mok C.C. et al.	2012	China	290 SLEc	<30 vs. < 15	anti-dsDNA, anti-C1q	0.02 0.02	[51]
Thudi A. et al.	2008	Texas, USA	37 SLE	>47 nmol/l vs. <47 nmol/l	anti-dsDNA	0.0069	[52]
AlSaleem A. et al.	2015	Saudi Arabia	28 SLE children (26 female, 2 male)	51.1 ± 33.6	anti-dsDNA, ANA	NS NS	[53]
Muller K. et al.	1990	Denmark	35 Sjogren	28.2 ± 12.4	IgM RF, IgA RF	<0.05 NS	[54]
Hajas A. et al.	2015	Hungary	125 MCTD, 48 CTRLd	26.16 ± 13.5	anti-U1-RNP, anti-CL IgA	0.022 0.015	[55]
Zold E. et al.	2008	Hungary	161 UCTD	NR; hypovitaminosis D	anti-U1-RNP, anti-SSA, anti-CCP	0.024 0.029 0.0001	[56]
Paupitz J.A. et al.	2010	Brazil	23 APSe, 23 CTRLf	21.64 ± 11.26 vs. 28.59 ± 10.67 mg/dl	IgG anti-CL IgM anti-CL	0.222 0.535	[57]
Arnson Y. et al.	2011	Israel	327 SSc, 141 CTRLg	18.2 ± 13.2 12.7 ± 6.6 16.8 ± 12.3	ANA, Anti-SCL70, RF	NS NS <0.001	[58]

SLE = Systemic lupus erythematosus; ANA = Antinuclear antibodies; anti-dsDNA = Anti-double stranded DNA antibodies; APS = Antiphospholipid syndrome; PV = Pemphigus vulgaris; IgM RF = IgM rheumatoid factor; IgA RF = IgA rheumatoid factor; anti-CL IgA = anti-cardiolipin IgA; RNP = ribonucleoprotein; anti-SSA = anti-Sjögren's-syndrome-related antigen A; anti-CCP = Anti-cyclic citrullinated peptide antibody; SSc = Systemic sclerosis; anti-SCL70 = anti-topoisomerase I; RF = Rheumatoid factor

^aHealthy matched controls; n=14 ANA-positive^{^}, n=18 ANA-negative^{^^}

^b5 mild vitamin D deficiency, 25 moderate vitamin D deficiency, 7 severe vitamin D deficiency

^c277 vitamin D insufficiency (<30 ng/ml), 77 vitamin D deficiency (<10 ng/ml)

^dage- and sex-matched healthy controls

^epre-menopausal women

^fage- and race-matched healthy controls

^ghealthy controls

^hCorrelation between vitamin D levels and positive CTD antibodies