Background
Acupuncture therapy has shown promise for effectively relieving preoperative anxiety. Nevertheless, previous findings from randomized controlled trials (RCTs) are inconsistent and must be examined in detail.

Objective
This study systematically evaluates the efficacy and safety of acupuncture therapy for preoperative anxiety as well as the quality of evidence supporting this application.

Search strategy
The China National Knowledge Infrastructure Database, Wanfang Data Journal Database, Chinese Biomedical Literature Database, Chongqing VIP, Embase, PubMed and Cochrane Library Databases were queried from their inception to 19, February 2020, using keywords such as “acupuncture therapy,” “preoperative” and “anxioty.” Manual searches expanded the search breadth and included conference abstracts and other reference lists.

Inclusion criteria
RCTs were included in the current study if they contained a comparison between a group of anxiety patients that received acupuncture therapy and a control group that received sham acupuncture.

Data extraction and analysis
Literature was reviewed, and various articles were selected using the NoteExpress 3.2.0 software. Two researchers independently screened and extracted data and evaluated the risk of bias in the included studies. The RevMan 5.3 software was used for data aggregation and the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) assessment was used to evaluate the quality of the study outcomes.

Results
Twelve studies were included in the review, containing a total of 916 patients. Meta-analysis showed that, compared with the control group, patients who received acupuncture therapy had reduced State-Trait Anxiety Inventory Scale (STAI-S) score (mean difference [MD] = –9.07, 95% confidence interval [CI] [–13.19 to –4.96], P < 0.0001) and Visual Analogue Scale (VAS) score (MD = –1.37, 95% CI [–2.29 to –0.45], P = 0.003). However, for the Hamilton Anxiety Scale (HAMA) score, there was no difference between the two groups (MD = –3.98, 95% CI [–12.89 to 4.92], P = 0.38). Further, the GRADE assessment demonstrated that the STAI-S was of moderate quality, the VAS of low quality and the HAMA of very low quality.

Conclusion
Acupuncture therapy may be able to decrease anxiety in preoperative patients, but the results need to be further verified due to the small sample sizes and the low quality of evidence to date.

Key words: Acupuncture, Preoperative anxiety, Meta-analysis, GRADE evaluation