Tibetan herbal pain-relieving plaster for low back pain: A systematic review and meta-analysis

Ethnopharmacological relevance: Tibetan traditional medicine CheeZheng Pain-Relieving Plaster (CZPRP) is frequently used as an over-the-counter external analgesic for musculoskeletal pain; however, its evidence for low back pain (LBP) has not been evaluated. Aim of the study: This study aims to assess the efficacy and safety of CZPRP for both acute, subacute and chronic LBP through a systematic review and meta-analysis of clinical trials. Materials and methods: PubMed, CENTRAL, CNKI, CQVIP, and Wanfang databases were searched through April 20, 2020 for randomized controlled trials of CZPRP for LBP. Eligible comparators were placebo, active treatment, or usual care. Clinical outcomes included pain severity, lower back function score, pain-free rate, and adverse events (AEs). Qualitative evaluations were conducted using the Cochrane risk of bias assessment tools. Quantitative analyses were conducted using a random-effects model. Results: This study includes 1674 LBP patients from nine clinical studies. Pooled analyses among subjects with acute LBP show 1) significant pain reductions (mean difference -0.84, 95% confidence interval[CI] -1.31, -0.37) in CZPRP plus diclofenac versus diclofenac, 2) significant improvements in lower back function (standard mean difference -1.50, 95% CI -2.16, -0.85) in CZPRP versus diclofenac, and 3) a higher pain-free rate in CZPRP alone (risk ratio 1.48, 95% CI 1.16, 1.89; I2 = 61%) or CZPRP plus nonsteroidal anti-inflammatory drugs (NSAIDs) (risk ratio 1.66, 95% CI 1.14, 2.40; I2 = 0%) versus NSAIDs. However, in a heterogeneous population with mixed LBP subtypes, there was no significant difference in pain outcomes between CZPRP and diclofenac. Additionally, CZPRP use did not increase AEs compared with no CZPRP (p = 0.40). All nine studies are associated with moderate to high risk of bias. Conclusions: The use of CZPRP is associated with improved acute LBP outcomes compared to diclofenac. However, due to the moderate to high risk of bias of the studies, future rigorous randomized controlled trials are needed to evaluate the effects of CZPRP for acute and chronic LBP.