P37 Assessing the impact of vitamin D status on disease status over 12 months in patients newly diagnosed with autoimmune hepatitis

<h3>Background</h3> Vitamin D is essential to healthy immune system function, and deficiency has been implicated in the pathogenesis of autoimmune disease.¹ Its role in autoimmune hepatitis (AIH) is unclear, but recent studies have linked severe deficiency to increased risk of disease flare, cirrhosis and mortality.^{2 3} <h3>Methods</h3> We analysed data from the prospectively recruited UKAIH cohort, for whom vitamin D, ALT, IgG and cirrhosis status were available at baseline (n=106), 12 months (n=75), or both (n=74). Biochemical remission was defined as both ALT and IgG below the upper limit of normal (ULN). For categorical analysis, vitamin D was sufficient (&gt;20 ng/ml), insufficient (10–20 ng/ml) or deficient (&lt;10 ng/ml), as per local laboratory values. <h3>Results</h3> 81/106 patients were female (76.4%); median age at diagnosis was 60.5 (18–83) years. All but 1 patient had abnormal ALT and/or IgG at time of diagnosis and 15 (14.1%) were cirrhotic. At 12 months from diagnosis (n=75), 49 (65.3%) were in complete biochemical remission. At diagnosis, 72 patients (67.9%) had inadequate vitamin D levels: 26 (24.5%) were vitamin D deficient, 46 (43.4%) insufficient, and 14 (32.1%) sufficient. At 12 months, 23 patients (30.7%) had inadequate vitamin D levels; 2 patients (2.7%) vitamin D deficient, 21 (28%) insufficient, and 52 (69.3%) sufficient. Table 1 summarises the results assessing associations between vitamin D status, ALT/IgG level, cirrhosis and biochemical remission status at 12 months. Median vitamin D at baseline was significantly lower in cirrhotic than non-cirrhotic patients (p=0.036). Vitamin D level was not associated with disease activity or remission status at 12-months of follow-up. Over 12 months, 1 patient newly developed cirrhosis, and 1 patient died. <h3>Conclusion</h3> To our knowledge, this is the 1st study to report prospective, longitudinal vitamin D measurement in incident patients with AIH. Our data showed lower vitamin D levels in cirrhotic patients at AIH diagnosis. However, vitamin D deficiency is well-recognised in cirrhosis of all aetiologies. We did not identify associations between vitamin D status/absolute values with either disease activity or biochemical remission status. It would be valuable to study a larger patient cohort with longer follow-up to hard outcome measures to further examine if there is any potential for vitamin D as a disease modifier. <h3>References</h3> Athanassiou L, Kostoglou-Athanassiou I, Koutsilieris M, <i>et al</i>. Vitamin D and autoimmune rheumatic diseases. <i>Biomolecules</i>. 2023;13:709 [Internet]. 2023 [cited 2025 Jun 5];13(4):709. Kilani Y, Alsakarneh S, Madi MY, <i>et al</i>. Autoimmune hepatitis and vitamin D deficiency: a nationwide perspective. <i>Aliment Pharmacol Ther</i> [Internet]. 2025 [cited 2025 Mar 4];61(4):682–692. Ebadi M, Bhanji RA, Mazurak VC, <i>et al</i>. Severe vitamin D deficiency is a prognostic biomarker in autoimmune hepatitis. <i>Aliment Pharmacol Ther</i> [Internet]. 2019 [cited 2025 Apr 23];49(2):173–182.