RESUMO
BACKGROUND: Along with increasing research on acupuncture for chronic pain, the validity of sham acupuncture (SA) has also been argued. METHODS: Nine databases were searched for randomized controlled trials (RCTs) from the inception dates of the databases to July 5, 2022. With Markov Chain Monte Carlo methods, a Bayesian multiple-treatment network meta-analysis (NMA) with random-effects model was conducted. RESULTS: A total of 62 RCTs with 6,806 patients and four kinds of treatments (real acupuncture [RA], non-acupuncture [NA], penetrative SA [PSA], and non-penetrative SA [NPSA]) were included. The results indicated that both NPSA and PSA were not superior to NA in improving chronic pain (NPSA: mean difference [MD]= -4.77, 95% confidence interval [CI] -11.09 to 1.52; PSA: MD= -4.96, 95% CI -10.38 to 0.48). After NPSA and PSA were combined into the SA group, the weak trend of pain relief from SA was still not statistically significant (MD= -4.91, 95% CI -9.93 to 0.05). NPSA and PSA had similar effects (MD= 0.18, 95% CI -5.45 to 5.81). RA was significantly associated with pain relief, compared with NPSA and PSA (NPSA: MD= -12.03, 95% CI -16.62 to -7.41; PSA: MD= -11.85, 95% CI -15.48 to -8.23). The results were generally consistent regardless of pain phenotype, frequency, duration, acupuncture methods, analgesic intake, or detection bias. CONCLUSION: These results suggested that acupuncture was significantly associated with reduced chronic pain. The two kinds of placebo acupuncture, NPSA and PSA, have similar effects. Both NPSA and PSA, with a weak but not significant effect, are appropriate to be inert placebo controls in RCTs for chronic pain.