Background
Treatment duration of wrist-ankle acupuncture (WAA) is uncertain for post-thyroidectomy pain relief.

Objective
This study evaluated the effect of different WAA treatment duration on post-operative pain relief and other discomforts associated with thyroidectomy.

Design, setting, participants and intervention
This randomized controlled trial was conducted at a single research site in Guangzhou, China. A total of 132 patients receiving thyroidectomy were randomly divided into the control group (sham WAA, 30 min) and three intervention groups (group 1: WAA, 30 min; group 2: WAA, 45 min; group 3: WAA, 60 min), with group allocation ratio of 1:1:1:1. Acupuncture was administered within 1 hour of leaving the operating room.

Outcomes and measures
Primary outcome was patients’ pain at the surgical site assessed by visual analogue scale (VAS) at the moment after acupuncture treatment (post-intervention). Secondary outcomes included the patients’ pain VAS scores at 6, 12, 24, 48 and 72 h after the thyroidectomy, the 40-item Quality of Recovery (QoR-40) score, the grade of post-operative nausea and vomiting (PONV), and the use of additional analgesic therapy.

Results
The adjusted mean difference (AMD) in VAS scores from baseline to post-intervention in group 1 was –0.89 (95% confidence interval [CI], –1.02 to –0.76). The decrease in VAS score at post-intervention was statistically significant in group 1 compared to the control group (AMD, –0.43; 95% CI, –0.58 to –0.28; P < 0.001), and in groups 2 and 3 compared to group 1 (group 2 vs group 1: AMD, –0.65; 95% CI, –0.81 to –0.48; P < 0.001; group 3 vs group 1: AMD, –0.66; 95% CI, –0.86 to –0.47; P < 0.001). The VAS scores in the four groups converged beyond 24 h after the operation. Fewer patients in group 2 and group 3 experienced PONV in the first 24 h after operation. No statistical differences were measured in QoR-40 score and the number of patients with additional analgesic therapy.

Conclusion
Compared with the 30 min intervention, WAA treatment with longer needle retention time (45 or 60 min) had an advantage in pain relief within 6 h after surgery. WAA’s analgesic effect lasted for 6–12 h post-operatively.

Key words: Thyroidectomy, Thyroid tumor, Wrist-ankle acupuncture, Post-operative pain, Randomized controlled trial