Abstract
BACKGROUND
Diffuse noxious inhibitory control (DNIC) is impaired in people with chronic pain such as knee osteoarthritis (KOA), which may predict the risk of acute-to-chronic pain transition. Electroacupuncture (EA) is effective in relieving pain in patients with KOA. However, whether EA may inhibit acute-to-chronic pain transition of KOA has not been systematically examined.
METHODS
This was a multicenter, three-arm parallel, single-blind randomized controlled trial involving a total of 450 patients with KOA. This study was approved by the Chinese Ethics Committee of Registering Clinical Trials (reference: ChiECRCT-20140035) and registered with Chinese Clinical Trial Registry (ChiCTR-ICR-14005411). Patients were divided into three groups based on EA current intensity: strong EA (>2mA), weak EA (<0.5mA) and sham EA (none acupoint). Treatments consisted of five sessions per week, for two weeks. Primary outcome measures were visual analog scale (VAS) and DNIC function.
RESULTS
One week of EA had no clinical important improvement in VAS and DNIC function in all three groups (P>0.05). After 2 weeks” treatment, changes from baseline showed that VAS (strong EA: 2.97, SD 0.10, P<0.0001; weak EA: 2.75, SD 0.15, P <0.0001; sham EA: 1.19, SD 0.14, P<0.0001) and DNIC (strong EA: −14.85, SD 0.16, P<0.0001; weak EA: −4.75, SD 0.28, P<0.0001; sham EA: −1.43, SD 0.24, P<0.0001) were significantly improved in all three groups. Compared with sham EA, weak EA (3.8, 95%CI 3.45 to 4.15) and strong EA (13.54, 95%CI 13.23 to 13.85) were better in improving DNIC function. Compared with weak EA, strong EA were better in enhancing DNIC function (9.73, 95%CI 9.44 to 10.02), as well as in reducing VAS.
CONCLUSIONS
In conclusion, EA should be administered 2 weeks to exerting significant effect on KOA. Strong EA was better than weak or sham EA in alleviating the intensity of pain and inhibiting the acute-to-chronic pain transition of KOA.
