#4768 25 HYDROXYVITAMIN D ASSOCIATES WITH GASTROINTESTINAL BLEEDING IN DIALYSIS
Authors: Larkin John , Jiao Yue , Lama Suman , Chaudhuri Sheetal , Willetts Joanna , Winter Anke , Stauss-Grabo Manuela , Usvayt Len , Hymes Jeffrey , Maddux Franklin , Wheeler David C , Stenvinkel Peter , Floege Jürgen 
Published: June 2023

Abstract

Background and Aims
The INSPIRE collaborative group built a prediction model that showed serum 25 hydroxyvitamin D concentration (25OH Vit D) may be a predictor of gastrointestinal bleeding (GIB) hospitalizations in dialysis patients [1]. Unexpectedly, 25OH Vit D levels in the target range (i.e., &gt;30 ng/mL) were most associated with GIB hospitalization risk. We aimed to further investigate the association between GIB episodes and 25OH Vit D levels, considering the onset of a GIB comorbidity or a GIB hospitalization event in the next 180 days.

Method
Analysis used data from adult (age ≥18 years) dialysis patients in the United States who had one or more 25OH Vit D lab measurement between 01-Jan-2018 to 31-Mar-2021. We identified GIB episodes (comorbidity or hospitalization observations) that were within ≤180 days after a 25OH Vit D measurement. GIB episodes and types were based on ICD-10 diagnosis code clusters defined by the United States Healthcare Cost and Utilization Project [2]. We calculated the percent of GIB comorbidities that onset, or GIB hospitalizations that occurred, by categories of 25OH Vit D levels (&lt;15, ≥15 to &lt;30, ≥30 to &lt;50, ≥50 to &lt;100, or ≥100 ng/mL).

Results
Among 347,165 adult dialysis patients who had a 25OH Vit D lab measurement(s), 3.2% (n = 11,038) experienced ≥1 GIB comorbidity and 6.7% (n = 23,389) experienced ≥1 GIB hospitalization. In total, 16.5% (n = 4,873) of these patients had ≥1 GIB comorbidity and hospitalization. GIB episodes were within ≤180 days after a 25OH Vit D measurement for 5,558 GIB comorbidity and 21,862 GIB hospitalization observations. We found patients with 25OH Vit D levels that were &lt;15 ng/mL or ≥50 ng/mL exhibited the lowest GIB comorbidity and GIB hospitalization rates (Figure 1A & B). Patients with 25OH Vit D levels that were between ≥15 ng/mL and &lt;50 ng/mL had the highest GIB comorbidity and GIB hospitalization rates. This observation was consistently observed for all GIB types, including upper, lower, and unspecified GIB episodes.

Conclusion
Findings showed serum 25OH Vit D levels are associated with 180-day GIB episodes in dialysis patients. The highest GIB rates were found in patients with a 25OH Vit D level between 15–50 ng/mL versus all other levels. This finding was consistent for the onset of a of GIB comorbidity and the occurrence of a GIB hospitalization, and in both cases was associated with 2-fold higher GIB rates. Outside the kidney failure population, 25OH vitamin D levels in the range of 30–100 ng/mL have been shown to be associated to higher GIB risk in warfarin users [3]. These findings may question recommendations in kidney disease that suggest repletion of 25OH Vit D levels to ≥30 ng/mL, which has been a controversy for more than a decade. Nonetheless, further analyses are needed and should consider adjustments for patient factors (e.g. age, sex, medications) and competing risks (non-GIB hospitalization events).