Dose-Response Relationship Between Acupuncture Parameters and Pain Reduction in Chronic Non-Specific Low Back Pain: A Systematic Review and Meta-Analysis.

BACKGROUND

Acupuncture is widely used for chronic non-specific low back pain (CNLBP), yet the optimal dosing parameters remain unclear. This systematic review and meta-analysis evaluated the overall efficacy of acupuncture for CNLBP and explored dose-response relationships between acupuncture parameters and pain reduction.

METHODS

PubMed, Embase, the Cochrane Library, and Web of Science were searched from inception to December 2025 for randomized controlled trials (RCTs) comparing acupuncture with sham, no-intervention, or active controls. The primary outcome was end-of-treatment pain intensity (VAS/NRS). Effect sizes were expressed as Hedges' g and pooled using a random-effects model (REML, Knapp-Hartung). Dose-response relationships for treatment sessions, duration, and needle retention time were examined by weighted meta-regression with restricted cubic splines (RCS).

RESULTS

Twelve randomized controlled trials involving 1,155 participants were included. Acupuncture significantly reduced pain intensity compared with controls (pooled Hedges' g = 0.57, 95% CI: 0.19-0.95), with substantial between-study heterogeneity (I2 = 85.3%). Exploratory dose-response and subgroup analyses indicated a potential nonlinear association for treatment duration - notably with a possible plateau or turning range around 6-7 weeks - though it was sensitive to the most influential trial and must be viewed as hypothesis-generating. Total sessions, needle retention time, and treatment frequency showed no significant dose-response relationships. No publication bias was detected, though statistical power was limited.

CONCLUSION

Acupuncture provides moderate pain relief for CNLBP. The observed nonlinear duration signal-including a potential turning range around 6-7 weeks-is preliminary and hypothesis-generating, given the high heterogeneity and sensitivity to the most influential trial. Session number and needle retention time showed no detectable dose-response association within the available evidence. Dedicated dose-finding trials are required.