The Effectiveness and Safety of Moxibustion for Treating Knee Osteoarthritis: A PRISMA Compliant Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND: Knee osteoarthritis (KOA) seriously affects people's life. Therefore, it has already become a worldwide health concern. Moxibustion has a significant clinical effect on KOA. This systematic review and meta-analysis is performed to renew previous studies and strictly evaluate the quality of RCT and thus test the effect and safety of moxibustion for KOA. OBJECTIVE: To evaluate the effectiveness and safety of moxibustion treatment for alleviating pain and improving lower limb function for patients with KOA. MATERIALS AND METHODS: CNKI (1979∼2019), CBM (1979∼2019), VIP (1989∼2019), WF (1998∼2019), PubMed (1966∼2019), Embase (1980∼2019), Cochrane Library, and Web of Science (1900∼2019) were all retrieved by a computer from their inception to June 02, 2019, replenished by manual retrieval of relevant bibliographies. Randomized controlled trials (RCTs) were included if moxibustion was compared to western medicine or negative control (placebo moxibustion or no treatment or UC) for treating KOA. The primary outcomes were the total effect and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC scale). The secondary outcomes include VAS, Symptom score, Lysholm score, and Lequesne score. RCTs were collected, and the quality of evidence was evaluated by using the Jadad scale and Cochrane risk assessment tools. We used RevMan5.3.0 software for meta-analysis. RESULTS: A total of 39 RCTs were included, including 3293 patients. In the assessment of the quality, the evidence differs from low to high based on the Cochrane Bias Evaluation Tools and Jadad scale. Fourteen trials were of high quality, ten were of moderate quality, and 15 were of low quality. Therefore, the quality of the included studies was moderate. In this study, there were 66.67% of the literature, and only 17.95% of the literature correctly reported randomized grouping and allocation of hidden information, respectively. In adverse reactions, only 13 trials included were reported in the study. The main adverse reactions of moxibustion are burns and blisters, whereas the western medicine group was in epigastric discomfort. As for the total effective rate, the meta-analysis of 27 RCTs showed a significant effect of moxibustion VS western medicine (RR = 1.20, 95% CI = 1.16 to 1.25, I(2) = 45%, P=0.007); as for the WOMAC scale, the subgroup meta-analysis of 13 trials showed that there was a statistically significant effect of moxibustion VS western medicine (MD = −11.08, 95% CI = −11.72 to −10.44, I(2) = 98%, P < 0.00001) and 2 trials on moxibustion VS negative control (MD = −8.38, 95% CI = −12.69 to −4.06, I(2) = 0%, P=0.77); as for the VAS score, the meta-analysis of 6 trials showed that there was a significant effect of moxibustion VS western medicine (MD = −2.12, 95% CI = −2.30 to −1.93, I(2) = 98%, P < 0.00001); as for the symptom score, the meta-analysis of 7 trials showed that there was a significant effect of moxibustion VS western medicine (MD = −0.81, 95% CI = −1.24 to −0.37, I(2) = 50%, P=0.06); as for the Lysholm score, the meta-analysis of 5 trials showed that there was a significant effect of moxibustion VS western medicine (MD = 7.61, 95% CI = 6.04 to 9.17, I(2) = 95%, P < 0.00001); and as for the Lequesne score, the meta-analysis of 3 trials showed that there was a significant effect of moxibustion VS western medicine (MD = 3.29, 95% CI = 2.93 to 3.65, I(2) = 99%, P < 0.00001). CONCLUSION: Moxibustion treatment for KOA is more effective than the positive control (western medicine) or negative control (placebo moxibustion or no treatment or UC), and there were fewer adverse reactions to moxibustion. Due to the universally low quality of the eligible trials, it still needs further large-scale and high-quality randomized controlled trials to verify the effectiveness and safety of moxibustion in the treatment of KOA.