The effect of vitamin D supplementation on the progression of fibrosis in patients with chronic liver disease: A protocol for a systematic review and meta-analysis

BACKGROUND: Hepatic fibrosis (HF) is the common pathological basis of chronic liver disease (CLD). Many data indicate that serum vitamin D (VD) levels in patients with liver fibrosis are significantly lower than those without liver fibrosis, and lower level of serum 1,25(OH)(2)D(3) is also an independent risk factor for patients with liver fibrosis combined with other diseases. VD has the functions of anti-fibrosis, regulating cell proliferation and differentiation, anti-inflammatory, and immune regulation, Therefore, serum 1,25(OH)(2)D(3) level may be negatively correlated with the progression of liver fibrosis. But there is absent convincing evidence-based medicine to confirm the efficacy of VD supplementation for CLD. Thus, we aimed to conduct this meta-analysis to summarize the efficacy of VD supplementation on the progression of fibrosis in patients with CLD. METHODS: The study only selects clinical randomized controlled trials of VD supplementation for CLD. We will search each database from the built-in until September 2020. The English literature mainly searches Cochrane Library, Pubmed, EMBASE, and Web of Science. While the Chinese literature comes from CNKI, CBM, VIP, and Wangfang database. Meanwhile, we will retrieve clinical trial registries and gray literature. Two researchers worked independently on literature selection, data extraction and quality assessment. The dichotomous data is represented by relative risk (RR), and the continuous is expressed by mean difference (MD) or standard mean difference (SMD), eventually the data is synthesized using a fixed effect model (FEM) or a random effect model (REM) depending on the heterogeneity. The serum VD level, hepatic function and serological indexes of hepatic fibrosis were evaluated as the main outcomes. While several secondary outcomes were also evaluated in this study. The statistical analysis of this Meta-analysis was conducted by RevMan software version 5.3. RESULTS: This meta-analysis will further determine the beneficial efficacy of VD supplementation on the progression of fibrosis in patients with CLD. CONCLUSION: This study determines the positive efficacy of VD supplementation for CLD. ETHICS AND DISSEMINATION: This review is based solely on a secondary study of published literatures and does not require ethics committee approval. Its conclusion will be disseminated in conference papers, magazines or peer-reviewed journals. REGISTRATION NUMBER: INPLASY202040054.