Background/Purpose:  The GI tract is one of the most commonly affected systems in SSc patients. GI disease in SSc patients is thought to be multifactorial and its pathogenesis remains elusive. Researchers suggest that malabsorption of vitamin D might impair enteric T-cell mediated immune response and affect the myenteric plexus leading to gastroparesis. Also, delayed GI motility has been associated with the development of bacterial overgrowth in SSc. Taken together, one can envision a system in which low levels of vitamin D, through its effect on cell dysregulation, may lead to decreased GI motility and small intestinal bacterial overgrowth (SIBO). This has been the basis of our hypothesis associating low levels of Vitamin D with GI manifestations and disease in SSc patients. Our objective in this study is to evaluate the methodology for assessing SIBO by means of Lactulose vs. Hydrogen Breath testing (LBT vs. HBT). To investigate SIBO and 25-OH Vitamin D levels in relation to other clinical markers of SSc activity.
Finally, to examine the relationship between SIBO (by means of LBT) and 25-OH Vitamin D levels in SSc patients.

Methods:   Retrospective analysis of all SSc patients from the UCLA SSc program and the UCLA- database. Those meeting the 2013 ACR/EULAR SSc classification criteria, and having 25- OH Vit. D with or without LBT and/or SIBO clinical diagnosis were included in this evaluation.
All patients with non-SSc diagnoses and those lacking Vitamin D levels were excluded. Logistic regression comparing LBT and hydrogen breath tests was used. A Chi-square test was used to test for difference in proportion of patients with low vitamin D among subjects who had a positive LBT compared to subjects who had a negative LBT.

Results: Of 2700 patients in the database, 608 met our inclusion criteria of having either Vitamin D levels or LBT. 163 did not have 25-OH Vitamin D, leaving 445 who were analyzed in this study. Subjects were between the ages of 48-69, with comparable female representation in both groups at 89 vs. 90% in LBT+ vs. LBT negative groups , respectively. We found a statistically significant difference in proportion of subjects who had low vitamin D in patients with positive LBT compared to those with negative LBT (p<0.001). We found a statistically significant difference in the false negative rate of the hydrogen test and the false negative rate of the methane test (p<0.001) indicating that Hydrogen Breath Testing is an adequate mode of testing for detecting SIBO in SSc.
Analysis of normal/high vitamin D, with LBT positivity, by means of logistic regression model, showed no association between both factors and either SSc type, or the presence of ILD or PAH.

Conclusion: Our preliminary data suggest a strong association between LBT positivity and low vitamin D level.
 Decreased gut motility may be at the core of the pathogenic pathways bridging hypovitaminosis D and SIBO.

« Back to 2016 ACR/ARHP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/vitamin-d-levels-and-gastrointestinal-gi-manifestations-in-systemic-sclerosis-ssc/