Efficacy and safety of acupuncture treatment for stiff neck: A systematic review and meta-analysis

This study represents a comprehensive analysis of the scientific literature on the use of acupuncture in the treatment of stiff neck, a common acute musculoskeletal condition that causes unilateral muscle tension, pain, stiffness, and limited neck mobility. Stiff neck significantly affects patients' quality of life, with an incidence rate in China of approximately 14.6% and an alarming recurrence rate of up to 85% within 1 to 5 years after the initial episode.

The researchers conducted a systematic review and meta-analysis following PRISMA guidelines, prospectively registered in the PROSPERO database. The search was performed across 8 Chinese and English medical databases through May 2024, including PubMed, Embase, Web of Science, Cochrane Library, and Chinese databases such as CNKI, Wanfang, VIP, and China Biology Medicine disc. Only randomized controlled trials evaluating acupuncture for stiff neck were included.

The analysis included 10 single-center Chinese studies with 754 patients, all following established and published diagnostic criteria. The treatment groups received acupuncture alone (2 studies) or combined with conventional treatment (8 studies), while the control groups received only conventional treatment. The acupuncture techniques included Millineed needles, electroacupuncture, and warm moxibustion. Sample size ranged from 46 to 110 cases, with mean patient age between 23 and 47 years, mean disease duration of 1 to 5 days, and treatment duration of 3 to 7 days.

The primary outcomes analyzed were the overall efficacy rate and visual analog scale (VAS) scores for pain. Secondary outcomes included the Neck Disability Index (NDI) and cervical range of motion. The meta-analysis using a random-effects model demonstrated that the acupuncture group was significantly superior to the control group across all evaluated outcomes.

Regarding the overall efficacy rate, acupuncture showed superiority with a risk ratio of 1.12 (95% CI [1.04, 1.21], P = 0.002), representing a 12% improvement in efficacy. For pain reduction, the acupuncture group showed a mean decrease of 0.93 points on the VAS compared to controls (95% CI [-1.29, -0.57], P < 0.001). The Neck Disability Index showed a reduction of 6.39 points in the acupuncture group (95% CI [-6.79, -6.00], P < 0.001). Cervical mobility also improved significantly, with a gain of 4.29 degrees in lateral flexion (95% CI [3.15, 5.43], P < 0.001) and 6.08 degrees in rotation (95% CI [4.46, 7.70], P < 0.001).

Subgroup analyses revealed that acupuncture was more effective in patients younger than 40 years and when the total course of treatment was 3 days or less. Trial sequential analysis confirmed that the cumulative evidence reached statistical significance, suggesting that future studies are unlikely to alter these conclusions. Sensitivity analysis demonstrated the robustness of the pooled results.

However, several important limitations should be considered. The quality assessment of the evidence using GRADEpro guidelines classified all outcomes as very low-quality evidence. The modified Jadad scale showed that most studies were classified as low quality, primarily due to lack of allocation concealment, inadequate blinding, and insufficient information about dropouts. Heterogeneity was high for primary outcomes (I² = 68% for efficacy rate and I² = 95% for VAS), suggesting multiple and complex sources of variability across studies.

The publication bias analysis using funnel plots and Egger's test revealed significant bias for both overall efficacy rate and pain scores. All studies were conducted exclusively in China, introducing clear geographic bias that may limit the global applicability of the results. Only one study reported adverse reactions, which may reflect the high safety of these therapies or inadequacies in monitoring and reporting adverse events.

In terms of clinical implications, this study provides preliminary evidence that acupuncture may be effective and safe for treating stiff neck, establishing a robust theoretical basis for its future clinical application. The findings suggest that acupuncture may accelerate recovery, significantly reduce pain, and improve cervical function compared to conventional treatment alone. The study also indicates that acupuncture may be particularly beneficial when applied early (≤3 days) and in younger patients (<40 years).