72 Vitamin D and Red Blood Cell Distribution Width: The Search for Predictive Markers in Primary Biliary Cholangitis Patients Receiving UDCA Continues

Abstract

INTRODUCTION: Serum Vitamin D and red blood cell distribution width (RDW) levels have been recently proposed as potential biomarker models to predict primary biliary cholangitis (PBC) severity and response to treatment. However, most of these studies were small with considerable limitations. Therefore, we aimed to investigate the predictive value of these novel markers in patients with PBC receiving ursodeoxycholic acid (UDCA). METHODS: We retrospectively reviewed PBC patients who received UDCA (13–15 mg/kg/day) at our tertiary care center between November 1998 and February 2017. Adverse events were defined as liver transplantation or liver-related death. Transplant-free survival (TFS) was estimated by Kaplan-Meier method. Serum Vitamin D and RDW levels were extracted from manual chart review at baseline and after one year of UDCA therapy. RESULTS: We identified 352 patients, 50 (14%) were male, 319 (91%) were Caucasian, with a median age of 55 years at diagnosis. Twenty-two (6%), 47 (13%), and 55 (16%) patients had adverse events within 5, 10, and 15 years after diagnosis, respectively (Table 1). In 197 patients of our cohort, we evaluated vitamin D levels at baseline and after 1 year of UDCA therapy while RDW levels were evaluated in all 352 patients. Median vitamin D levels before and after 1 year of UDCA treatment were 15.9 (range: 7.2–21.8) and 16.0 (range: 12.8–45.4) in patients with adverse events (P = 0.05) vs. 13.7 (range: 7.0–88.6) and 13.8 (range: 7.5–63.0) in patients with no adverse events (P = 0.72), respectively. Median red cell distribution width (RDW) before and after 1 year of UDCA treatment in patients with adverse event vs. no adverse event were 16.9 (range: 7.0–66.0) and 16.5 (range: 8.8–160.0), P = 0.14, vs. 17.0 (range: 4.5–62.3) and 16.4 (range: 8.9–69.5), P = 0.06, respectively (Figure 1). Moreover, RDW pre/post UDCA treatment ratio was not a reliable marker for treatment response (overall ratio 1; P = 0.048). CONCLUSION: Our study doesn't support the routine use of the newly suggested biomarker prognostic models in patients with PBC receiving UDCA. Presence of multiple confounding factors such as sun exposure, vitamin D or iron supplementation, anemia, folate and vitamin B 12 levels limit the clinical utility of RDW and Vitamin D levels as predictive models for PBC patients.