Protocol for thiamine and folic acid in the treatment of cognitive impairment in maintenance haemodialysis patients: a prospective, randomised, placebo-controlled, double-blind, multicentre study

INTRODUCTION: Cognitive impairment (CI) is the common complications in maintenance haemodialysis (MHD) patients. Recently, the pathogenesis of CI has been discussed and oxidative stress is one of the main mechanisms in these patients. Thiamine and folic acid, which play an important role in relieving the production of reactive oxygen species, reducing homocysteine levels, improving oxidative stress in the nervous system. In pilot study, cognitive function was significantly improved in the group with thiamine and folic supplementation. Based on this result, we hypothesise that thiamine combined with folic acid supplementation may improve cognitive function in patients with MHD. METHODS AND ANALYSIS: In this prospective, randomised, placebo-controlled, double-blind, multicentre study, we will enrol patients undergoing haemodialysis who has the Montreal Cognitive Assessment score lower than 26 to treatment group (thiamine 90 mg/day combined with folic acid 30 mg/day) or control group (thiamine placebo 90 mg/day combined with folic acid placebo 30 mg/day). All subjects will be followed up for 96 weeks. The primary endpoint is the comparison of Alzheimer’s Disease Assessment Scale-Cognitive Subscale (ADAS-Cog) score between treatment group and control group at 96 weeks of follow-up. The secondary endpoints include serum thiamine, folate, homocysteine levels, cranial functional MRI and survival. The central randomisation method will be adopted and the principles of placebo-controlled, double-blind randomised control will be followed. The comparisons among ADAS-Cog scores and other secondary endpoints over time within subjects is conducted by using repeated measure analysis of variance (ANOVA) or generalised estimating equations (GEE). Pairwise t-test with Bonferroni adjustment is performed for multiple comparisons. On the other hand, for comparisons between treatment and control group, simple one-way ANOVA, GEE or Wilcoxon rank sum test is used. The χ(2) method is used for statistical analysis of the categorical data. Kaplan-Meier survival curve is used for survival analysis. A p<0.05 is considered statistically significant difference. ETHICS AND DISSEMINATION: This trial has been approved by Shanghai Jiao Tong University School of Medicine, Renji Hospital Ethics Committee (KY2019-199). After publication of study results, trial report will be published in peer-reviewed journals and/or in national or international conferences. TRIAL REGISTRATION NUMBER: ChiCTR2000029297.