Transcutaneous auricular vagus nerve stimulation for functional dyspepsia: A systematic review and meta-analysis

Transcutaneous auricular vagus nerve stimulation (taVNS) is a potential noninvasive treatment for functional dyspepsia (FD). We aimed to systematically analyze the clinical evidence of taVNS for FD.

Eight databases were searched to identify randomized controlled trials (RCTs) using taVNS in patients with FD published by June 27, 2024. The primary outcome was dyspepsia symptoms, whereas the secondary outcomes were the total effective rate (TER), quality of life, anxiety, depression, and incidence of adverse events. The certainty of the evidence was assessed using the GRADE methodology. Detailed information on the taVNS parameters and the suggested underlying mechanism were also extracted.

Six RCTs with 716 participants were included. Compared to the sham intervention, taVNS significantly improved dyspepsia symptoms, quality of life, and clinician-rated anxiety and depression with moderate certainty of evidence. The TER based on dyspepsia symptoms was also significantly higher with high certainty of evidence. When taVNS was used as an add-on therapy, dyspepsia symptoms were significantly improved with moderate certainty of evidence. No serious adverse events related to taVNS were reported. The stimulation sites for taVNS were concha and tragus, with common pulse frequencies of 25 or 20 Hz twice a day for 2-4 weeks. Gastric accommodation, electrogastrogram, heart rate variability, and functional magnetic resonance imaging were measured to explore the mechanism of taVNS.

Considering the certainty of the evidence, taVNS can improve dyspepsia symptoms, quality of life, anxiety, and depression in patients with FD without serious adverse events. Additional high-quality studies are needed to establish optimal treatment protocols.