The dose-response association between acupuncture sessions and acupuncture effects on dysmenorrhea: a systematic review and dose-response meta-analysis of randomized controlled trials

Background: Acupuncture is a common treatment for dysmenorrhea. However, there is still uncertainty regarding the efficacy of acupuncture for patients with dysmenorrhea and the dose-response relationship between acupuncture and dysmenorrhea. Objectives: This study aimed to explore the relationship between acupuncture and pain relief in dysmenorrhea patients based on previously published randomized controlled trials (RCTs). Search strategy Eight databases including English, Chinese database, were searched from inception until May 2023. Selection criteria RCTs Comparing Acupuncture with Sham Acupuncture, Western medicine, or no intervention for treatment. Data collection and analysis The study abstraction and quality assessment of all studies were undertaken following the detailed descriptions of these categories as described in the Cochrane Handbook for Systematic Reviews of Interventions. Main outcome The outcome measures were menstrual pain intensity on numerical rating scale scores (VAS). Results: The meta-analysis of pain change scores indicated that acupuncture had beneficial effect [n = 492; SMD = −2.29, 95% CI (-3.57, -1.01); I 2 = 94.7%]. The meta-regression model and the results indicated that acupuncture sessions were associated with greater reducing menstrual pain. A V-shaped association between acupuncture sessions with VAS scores was presented: After 10 acupuncture sessions, the pain reduction was optimal at 2.06 (95% CI: 1.46–2.66), with a difference of −4.06 (95% CI: −4.73 to −3.39). Conclusion: Acupuncture can effectively relieve dysmenorrhea. A dose-effect relationship was found between the number of acupuncture sessions and VAS scores. 10 acupuncture sessions may associate with optimal clinical response.