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.