Efficacy of acupuncture for tension-type headache prophylaxis: systematic review and meta-analysis with trial sequential analysis

BackgroundAcupuncture has been shown to reduce tension-type headache (TTH) frequency in previous studies. Nevertheless, repeated significance testing might inflate type I error. We aimed to verify the effectiveness and safety of acupuncture in reducing TTH frequency by meta-analysis and trial sequential analysis (TSA).MethodsOvid Medline, Embase, and Cochrane Library were searched until September 29, 2022. Randomized controlled trials comparing acupuncture with sham acupuncture, no acupuncture, or other active therapies in adults with TTH were included. The primary outcome was TTH frequency. The secondary outcomes were responder rate and adverse event.ResultsFourteen studies involving 2795 participants were included. Acupuncture had more reduction than sham acupuncture in TTH frequency, both after treatment (standardized mean difference [SMD] - 0.80, 95% CI - 1.36 to - 0.24, P = 0.005) and at the follow-up period (SMD - 1.33, 95% CI - 2.18 to - 0.49, P = 0.002), while TSA showed the included sample size did not exceed required information size (RIS). Acupuncture was superior over no acupuncture after treatment (SMD - 0.52, 95% CI - 0.63 to - 0.41, P < 0.001), and cumulative sample size reached RIS. In terms of responder rate, acupuncture had a higher responder rate compared with sham acupuncture both after treatment (relative ratio [RR] 1.28, 95% CI 1.12 to 1.46, P = 0.0003) and the follow-up period (RR 1.37, 95% CI 1.19 to 1.58, P < 0.0001), but the sample size is inadequate.ConclusionAcupuncture is an efficacious and safe treatment for TTH prevention, but this conclusion might be limited by the generally very low to low quality evidence. TSA suggested that high-quality trials are needed to verify the efficacy and safety of acupuncture compared to sham acupuncture.