Prognostic value of gut microbiota-derived trimethylamine N-oxide in patients with ischemic stroke: A meta-analysis

Objective: This study aimed to evaluate the relationship between the intestinal microbial metabolite trimethylamine N-oxide (TMAO) level in the plasma and the outcomes of patients with ischemic stroke (IS).Methods: The PubMed, Web of Science, Cochrane Library, and Embase databases were systematically searched until July 1, 2022 to identify clinical studies on TMAO levels and prognosis of IS. The identified studies were then screened according to the inclusion and exclusion criteria, and a meta-analysis on the final included studies was performed using the Stata (version 17.0) software to investigate the effects of TMAO level on the prognosis of IS.Results: Four studies involving 1,026 participants from 2019 to 2022 were considered. The results indicated an association between high circulating TMAO concentration and poor functional outcomes (rate ratio [RR]: 2.76; 95% confidence interval [CI]:1.33,5.72; P = 0.006; I2 = 72.7%; P-heterogeneity = 0.012; random-effects model), mortality (RR: 5.37; 95%CI: 2.63,10.97; P < 0.001; I2 = 0.0%; P-heterogeneity = 0.704; fixed-effects model), and recursive ischemic events (RR: 2.71; 95%CI: 1.68,4.36; P < 0.001; I2 = 0.0%; P heterogeneity = 0.779; fixed-effects model) 3 months after IS.Conclusions: Elevated TMAO level may be an adverse prognostic indicator in patients with IS.