Study design, materials and methods
We performed a comprehensive search of medical literature, including Cochrane Library, MEDLINE, EMBASE, Chinese Biomedical Literature Database, trials registries, with no restrictions on the language of publication or publication status. The date of the latest search of all databases was February 22, 2019. In this systematic review, we only included randomized controlled trials (RCTs). Inclusion criteria were children with primary nocturnal enuresis, and age 5 to 21 years. Trials of children with secondary nocturnal enuresis were excluded. The intervention we focused on in this review was acupuncture and the controls included conventional drug, sham acupuncture, and Chinese herbal therapy. The primary outcome was complete response rate and the secondary outcomes included number of nocturnal enuresis, and the adverse events. After two reviewers screened the studies, extracted data from including studies, and rated the quality of evidence independently, we performed meta-analysis using software of Revman version 5.3 and interpreted data according to the Cochrane Handbook for Systematic Reviews of Interventions.
A total of 10 studies with 953 randomized participants (441 in acupuncture group and 412 in control group) were included. The results of meta-analysis showed that, compared with the control group, the acupuncture group had statistically significant higher complete response rate [OR=2.41, 95%CI (1.41, 4.93)，P=0.002], so did the statistical significance when compared with conventional drug group [OR=2.46, 95%CI (1.69, 3.60)，P<0.00001], sham acupuncture group [OR=9.14, 95%CI (2.46, 33.92)，P=0.0009], and herbal therapy group [OR=1.78, 95%CI (1.13, 2.79)，P=0.01] respectively. Moreover, although acupuncture did not reduce the average number of nocturnal enuresis in comparison with control intervention [MD=-0.93, 95%CI (-1.95, 0.09)，P=0.07], a significant decrease was found when compared to the sham acupuncture [MD=-1.49, 95%CI (-2.26, -0.72)，P=0.0002]. In terms of adverse events, there was no significant difference between acupuncture group and control group [OR=0.62, 95%CI (0.04, 8.72)，P=0.72].
Interpretation of results
Nocturnal enuresis is a common disorder in children and has a significant negative effect on emotional state, self-esteem, as well as the social development of a child. The current treatment of nocturnal enuresis includes behavior intervention, alarm therapy, and pharmacotherapy. However, these therapeutic options cannot meet the needs of children and their parents due to limited effectiveness, inconvenience, and troublesome adverse events.
Acupuncture, as an important component of traditional Chinese medicine, has gained the acceptance in management of various urological diseases worldwide. The result of our current systematic review shows that acupuncture has a better efficacy and similar adverse events in managing nocturnal enuresis in children compared with other intervention. Through literature search, we have also identified three published systematic reviews assessing the efficacy and safety of acupuncture for children with nocturnal enuresis [1-3]. Differing from our finding, two reviews [1, 2] demonstrated a similar effectiveness between acupuncture and conventional drug. The potential reason for the inconsistency may result from the fact that our review included more recent trials. Furthermore, these two reviews included observational studies besides RCTs, which might contribute to the difference in findings. Another systematic review  presented the similar findings with ours. However, that review included the studies using acupoint injection as an intervention. The result form these studies may not present the accurate effect of acupuncture because acupoint injection provides an additional chemical stimulation beside the physical stimulation result from acupuncture.
The current evidence shows that acupuncture has a better effect in management of primary nocturnal enuresis in children, and a similar risk of adverse events, when compared to conventional drug, sham acupuncture, and herbal therapy respectively. However, further study is still needed since the findings of this review were limited by the limitations of included studies.