Analgesic Effect of Electroacupuncture on Postherpetic Neuralgia: A Trial Protocol for a Multicenter Randomized Controlled Trial

Abstract

Introduction: The chronic neuropathic pain associated with postherpetic neuralgia (PHN) can last for several months or even many years, seriously affecting the affected person's work, sleep, mood, and daily life activities. In generaly, current treatments for PHN are at best limited and unsatisfactory, and adverse reactions are common, especially in elderly patients. Electroacupuncture (EA) is widely used clinically to manage painful diseases, but there remains a lack of evidence to support the effectiveness of EA on PHN. This study is designed to assess the efficacy and safety of EA on PHN, and to provide evidence-based medical evidence for EA treatment of PHN.

Methods: This multicenter, prospective, randomized controlled trial will recruit 448 patients with PHN at seven clinical centers. Multicenter stratified variable block randomization will be used, and the eligible patients will be randomly allocated in a ratio of 1:1 to the EA group or sham EA group. The EA group will receive 4 weeks of EA treatment, given as 30-min treatment sessions, once daily, 5 times per week, for a total of 20 treatments; the sham EA group will receive sham EA treatment under the same conditions.

Planned outcomes: The primary outcome measure is the 11-point Numeric Rating Scale pain score at week 4. The secondary outcome measures, including mechanical pain threshold, pain area of PHN, average number of pain episodes, the short-form McGill Pain Questionnaire 2, Zoster Brief Pain Inventory, the Depression, Anxiety, and Positive Outlook Scale, Patient Global Impression of Change, safety of EA, and use of concomitant medications, among others. The primary analysis of the outcomes will be the mixed-effect model with repeated measurement between groups on an intent-to-treat population.

Trial registration: Clinicaltrials.gov identifier: NCT04560361. Registered 23 September 2020 ( https://ichgcp.net/clinical-trials-registry/NCT04560361?term=NCT04560361&draw=2&rank=1 ).

Keywords: Analgesic effect; Electroacupuncture; Postherpetic neuralgia; Randomized controlled trial; Trial protocol.

© 2021. The Author(s).

Figures

Fig. 1

Study design. Screening and randomization will be performed based on an average daily pain score of ≥ 4, assessed using the 11-point Numeric Rating Scale (NRS-11) during the observation period. Electroacupuncture treatment arms are shown in orange and gray. Patients will be followed up for 1 month after treatment. Asterisk: The washout period is required only for specific patients, namely, those currently receiving or having received > 1 permitted concomitant medication or any prohibited concomitant medications and treatments listed in sectionConcomitant Medications for the treatment of postherpetic neuralgia within 14 days; for these patients, a washout period of > 7 days (depending on the half-life of the medications) is required after informed consent

Fig. 2

Flow diagram of patient enrollment. The yellow dotted box indicates that patients who meet the standards of concomitant medications do not require a washout period and can directly enter the observation period. EA Electroacupuncture, PHN postherpetic neuralgia, SEA sham electroacupuncture

Fig. 3

Location of acupoints in the study, and acupuncture procedure for the EA and SEA groups. a Disposable acupuncture needles (size 0.30 × 40 mm). b Placebo blunt needles (size 0.40 × 13 mm). c Insulating adhesive pads. d Location of ipsilateral (PHN-affected side) acupoints in the study. For example, for PHN in the left lumbar, choose the Zhigou (SJ6), Yanglingquan (GB34), and Ashi points on the left side for the EA treatment; refer to the same location on the right. d′ Enlarged view of the location of Ashi points. Every 2- to 3-cm interval around the painful area of PHN is used as an acupuncture point, with the needle pointed towards the painful area. e Operating diagram of inserting needle vertically into the Zhigou and Yanglingquan points in the EA group. f Operating diagram of inserting needle obliquely (at an angle of 30°–45°) into the Ashi points in the EA group. g Operating diagram of inserting needle vertically into the Zhigou and Yanglingquan points in the SEA group. h Operating diagram of inserting needle obliquely (at an angle of 30°–45°) into the Ashi points in the SEA group

Fig. 4

Schedule of study procedures. MPT Mechanical pain threshold, ANPE average number of pain episodes, ADEPE average duration of each pain episode, SF-MPQ-2 short-form McGill Pain Questionnaire 2, ZBPI Zoster Brief Pain Inventory, APOS Depression, Anxiety and Positive Outlook Scale, PGIC Patient Global Impression of Change, SEA safety of electroacupuncture