Vitamin D deficiency and reduced lung function in connective tissue-associated interstitial lung diseases.
BACKGROUND
Vitamin D is a steroid hormone with pleiotropic effects including immune system modulation, lung tissue remodeling, and bone health. Vitamin D deficiency has been implicated in the development of autoimmune diseases. We sought to evaluate the prevalence of vitamin D deficiency in a cohort of patients with interstitial lung disease (ILD) and hypothesized that vitamin D deficiency would be associated with an underlying connective tissue disease (CTD) and reduced lung function.


METHODS
Patients in the University of Cincinnati ILD Center database were evaluated for serum 25-hydroxyvitamin D levels as part of a standardized protocol. Regression analysis evaluated associations between 25-hydroxyvitamin D levels and other variables.


RESULTS
One hundred eighteen subjects were included (67 with CTD-ILD, 51 with other forms of ILD). The overall prevalence of vitamin D deficiency and insufficiency in the study population was 38% and 59%, respectively. Those with CTD-ILD were more likely to have vitamin D deficiency (52% vs 20%, P < .0001) and insufficiency (79% vs 31%, P < .0001) than other forms of ILD. Diminished FVC was associated with lower 25-hydroxyvitamin D(3) levels (P = .01). The association between vitamin D insufficiency and CTD-ILD persisted (OR, 11.8; P < .0001) after adjustment for potential confounders. Among subjects with CTD-ILD, reduced 25-hydroxyvitamin D(3) levels were strongly associated with reduced lung function (FVC, P = .015; diffusing capacity for carbon monoxide, P = .004).


CONCLUSIONS
There is a high prevalence of vitamin D deficiency in patients with ILD, particularly those with CTD-ILD, and it is associated with reduced lung function. Vitamin D may have a role in the pathogenesis of CTD-ILD.
Hagaman
Jared T
JT
Division of Pulmonary, Critical Care, and Sleep Medicine, University of Cincinnati College of Medicine, Cincinnati, OH.
Panos
Ralph J
RJ
Division of Pulmonary, Critical Care, and Sleep Medicine, University of Cincinnati College of Medicine, Cincinnati, OH.
McCormack
Francis X
FX
Division of Pulmonary, Critical Care, and Sleep Medicine, University of Cincinnati College of Medicine, Cincinnati, OH.
Thakar
Charuhas V
CV
Division of Nephrology and Hypertension, University of Cincinnati College of Medicine, Cincinnati, OH.
Wikenheiser-Brokamp
Kathryn A
KA
Department of Pathology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, OH.
Shipley
Ralph T
RT
Department of Radiology, University of Cincinnati College of Medicine, Cincinnati, OH.
Kinder
Brent W
BW
Division of Pulmonary, Critical Care, and Sleep Medicine, University of Cincinnati College of Medicine, Cincinnati, OH. Electronic address: brent.kinder@uc.edu.
D000368:Aged; D000704:Analysis of Variance; D016009:Chi-Square Distribution; D003240:Connective Tissue Diseases / Q000150:complications* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D017563:Lung Diseases, Interstitial / Q000209:etiology* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012044:Regression Analysis; D012129:Respiratory Function Tests; D014808:Vitamin D Deficiency / Q000150:complications* / Q000453:epidemiology / Q000503:physiopathology*