Topical Chinese patent medicines for chronic musculoskeletal pain: systematic review and trial sequential analysis

Chronic musculoskeletal pain (CMP) is defined as persistent or recurrent pain that occurs in the joints, musculo-soft tissue, spine or bones for more than three months and is not completely curable. Although topical Chinese patent medicine (CPM) is the most extensively utilized medication in Asia and is widely used for pain management, its efficacy remains controversial. This article presents a systematic review of clinical studies on the therapeutic properties of topical CPM for CMP patients to better inform clinical decision-making and provide additional and safer treatment options for patients with CMP.

We performed a comprehensive search on PubMed, Cochrane Library, web of science and Chinese databases (CNKI and WanFang data) from 2010 to 2022. In all the studies, knee osteoarthritis, cervical spondylosis, low back pain, and periarthritis of shoulder met the International Pain Association definition of chronic musculoskeletal pain. We included only randomized controlled trials (RCTs) using topical CPM primarily for chronic musculoskeletal pain in adults. To determine the effect of topical CPM on clinical symptoms, we extracted the Visual Analog Scale (VAS, range 0-10) and the Western Ontario and McMaster Universities Arthritis Index pain scores (WOMAC pain, range 0-20), in which the lower the score, the better the results. We also accepted the comprehensive outcome criteria developed by the Chinese National Institute of Rheumatology as an endpoint (total effectiveness rate, range 0-100%, higher score = better outcome), which assesses the overall pain, physical function and wellness. Finally, trial sequential analysis of VAS pain score and total effectiveness rate was performed using TSA software.

Twenty-six randomized controlled trials (n = 3180 participants) compared topical CPM with oral Nonsteroidal Anti-inflammatory Drugs (NSAIDs) (n = 15), topical NSAIDs (n = 9), physiotherapy (n = 5), exercise therapy (n = 4), and intra-articular Sodium hyaluronate injection (n = 2). Sixteen studies found that topical CPM was statistically significant in improving CMP pain (measured by VAS pain and Womac pain scores)(p < 0.05), and 12 studies found topical CPMs to be more clinically effective (assessed by ≥ 30% reduction in symptom severity) in treating patients with CMP (p < 0.05). Trial sequential analysis indicates that the current available evidence is robust, and further studies cannot reverse this result. In most of the studies, randomisation, allocation concealment and blinding were not sufficiently described, and no placebo-controlled trials were identified.

Most studies showed superior analgesic effects of topical CPM over various control treatments, suggesting that topical CPM may be effective for CMP and is an additional, safe and reasonable treatment option. These reported benefits should be validated in higher-quality RCTs.