Efficacy and safety of acupuncture for vocal nodules: A systematic review and meta-analysis with trial sequential analysis

In this study, we aim to evaluate the efficacy and safety of acupuncture for vocal nodules, concerning qualitive overall efficacy and quantitative improvement on quality of voice. Four English and four Chinese databases were searched up to December 10(th), 2022. Risk of bias among the included trials were evaluated by the Cochrane ROB tool. Systematic reviews and meta-analyses were conducted based on the Cochrane systematic review method by using RevMan 5.4 Software, and trial sequential analyses were performed by TSA 0.9. Meta-influence analyses, subgroup-analyses, meta-regression, and evaluation of publication bias were performed for exploration of heterogeneity by Stata V.14. Quality of the results was accessed through the GRADE-pro GDT. Cluster analyses and correlation coefficient were performed by R 4.1.3. Finally, 15 trials involving 1,888 participants were included. Results showed that compared with western medicine alone or Chinese herbal medicine alone, acupuncture alone yielded significantly (p<0.05) higher clinical effective rate and more improvement on scores of voice analyses. However, reduction on scores of grade, roughness, and breathiness and voice handicap index during follow-ups, and results of clinical effective rate suggested that acupuncture was inferior to voice training. In addition, meta-regression and sub-group analyses firstly revealed advanced efficacies of acupuncture when performed with local and remote acupoints, compared with local acupoints only. Acupuncture specified adverse event was denied in six trials while it was not mentioned in other nine trials. Results of cluster analyses and correlation coefficient showed that Kai yin yi hao and He gu (LI-4) were the most frequently applied matching-acupoints in trials. In conclusion, compared with western medicine (level of evidence: low ⨁⨁◯◯, GRADE C) and Chinese herbal medicine (level of evidence: moderate ⨁⨁⨁◯, GRADE B), acupuncture is safe and of better efficacy for patients with vocal nodules, while there is also need for RCTs with improvements on designing and interventions in experimental and controls.