Cupping therapy versus acupuncture for pain-related conditions: a systematic review of randomized controlled trials and trial sequential analysis

Source: Chinese Medicine BioMed Central

© The Author(s) 2017
Received: 26 April 2017

Abstract
Background
Both cupping therapy and acupuncture have been used in China for a long time, and their target indications are pain-related conditions. There is no systematic review comparing the effectiveness of these two therapies.

Objectives
To compare the beneficial effectiveness and safety between cupping therapy and acupuncture for pain-related conditions to provide evidence for clinical practice.

Methods
Protocol of this review was registered in PROSPERO (CRD42016050986). We conducted literature search from six electronic databases until 31st March 2017. We included randomized trials comparing cupping therapy with acupuncture on pain-related conditions. Methodological quality of the included studies was evaluated by risk of bias tool. Mean difference, risk ratio, risk difference and their 95% confidence interval were used to report the estimate effect of the pooled results through meta-analysis or the results from each individual study. Trial sequential analysis (TSA) was applied to adjust random errors and calculate the sample size.

Results
Twenty-three randomized trials with 2845 participants were included covering 12 pain-related conditions. All included studies were of poor methodological quality. Three meta-analyses were conducted, which showed similar clinical beneficial effects of cupping therapy and acupuncture for the rate of symptom improvement in cervical spondylosis (RR 1.13, 95% CI 1.01 to 1.26; n = 646), lateral femoral cutaneous neuritis (RR 1.10, 95% CI 1.00 to 1.22; n = 102) and scapulohumeral periarthritis (RR 1.31, 95% CI 1.15 to 1.51; n = 208). Results from other outcomes (such as visual analogue and numerical rating scale) in each study also showed no statistical significant difference between these two therapies for all included pain-related conditions. The results of TSA for cervical spondylosis demonstrated that the current available data have not reached a powerful conclusion. No serious adverse events related to cupping therapy or acupuncture was found in included studies.

Conclusion
Cupping therapy and acupuncture are potentially safe, and they have similar effectiveness in relieving pain. However, further rigorous studies investigating relevant pain-related conditions are warranted to establish comparative effectiveness analysis between these two therapies. Cost-effectiveness studies should be considered in the future studies to establish evidence for decision-making in clinical practice.
Keywords
AcupunctureCupping therapyRandomized controlled trialSystematic reviewTrial sequential analysis

Background
Traditional Chinese non-pharmaceutical therapies, such as acupuncture, are applied under the guidance of the Traditional Chinese Medicine (TCM) theory of syndrome differentiation. As an important part of TCM, these therapies mainly use manual or technique stimulations at specific body parts (especially acupoints) to dredge the meridian system. Generally, non-pharmaceutical therapies, including acupuncture, cupping therapy, moxibustion, massage (tuina), and guasha, are more likely to be accepted by patients since they have been used in treating numerous diseases or conditions and may have fewer side effects than drugs [1]. Acupuncture, as one of the most popular non-pharmaceutical therapy, has been widely used to treat diseases by regulating the functions of qi (vital energy) and blood of the organs through puncturing certain acupoints of meridians in the body with needles, to strengthen the resistance of the body against diseases [2]. A current clinical guideline issued by the American College of Physicians (ACP) recommends non-pharmacologic treatments (such as acupuncture, massage and superficial heat) as the priority treatments to patients with acute, subacute or chronic low back pain [3]. In addition, systematic reviews have reported that acupuncture was indicated for the treatment of chronic pain, mainly headaches, migraines, cervical pain, back pain, and pain from osteoarthritis [4, 5, 6, 7, 8, 9].

Cupping therapy also belongs to TCM non-pharmaceutical therapy, which has been used for long time [10]. Cupping practitioners utilize the flaming heating power to achieve suction (minus pressure) inside the glass cups to make them apply on the desired part of the body, and this suction on selected acupoints produces hyperemia or hemostasis, which may result in a therapeutic effect [11]. There are different types of cupping including retained cupping, flash cupping, moving cupping, wet cupping, medicinal cupping, and needling cupping [12]. Since a report about the Olympic swimmer Michael Phelps using cupping therapy to relieve his muscular discomfort, this treatment has become more and more popular outside China. However, although beneficial effects of cupping therapy have been reported in treating various diseases/conditions, there is lack of high-quality evidence to confirm its efficacy [13]. Our previous systematic reviews on cupping for pain-related conditions also identified no high-quality evidence to prove its effectiveness [14, 15].

Both acupuncture and cupping therapy are commonly used in treating similar conditions, especially pain-related conditions. Though the mechanism of acupuncture and cupping therapy may be different, both, therapies employ the meridian and acupoints to activate blood stasis and regulate the flow of qi to relieve pain. Cupping therapy has more advantages than acupuncture, such as a non-invasive therapy with relatively shorter treatment duration and potential less treatment cost. It is worthy to critically review the evidence of the comparison of these two therapies to inform clinical practice. Herein, to the objective of this review is to comprehensively review the evidence from randomized controlled trials (RCTs) comparing cupping therapy with acupuncture for pain-related conditions.
Methods
The protocol of this review was registered in PROSPERO (CRD42016050986) on 15th November 2016 (Achieved at http://www.crd.york.ac.uk/PROSPERO/). Since pain-related conditions were most commonly treated by cupping therapy and acupuncture, we limited the target conditions (such as musculoskeletal pain, tissue pain and neuralgia pain) in this review to reduce the clinical heterogeneity among included studies.

Inclusion criteria
RCTs comparing cupping therapy with acupuncture were included. Pain-related conditions were classified by the type of tissue according to international statistical classification of disease and health related problems by World Health Organization [16], including musculoskeletal system pain (such as spondylopathies, lumbar spondylosis, knee osteoarthritis, acute tissue pain), and neurologic pain (such as lateral femoral cutaneous nerve and herpes zoster pain). Acupuncture is defined as the insertion of fine needles, sometimes in conjunction with electrical stimulus, to influence physiological functioning of the body. In this review, we included both manual acupuncture (including auricular therapy, scalp needle, and abdominal acupuncture) and electro-acupuncture. Cupping is defined that practitioners utilize the flaming heating power to achieve suction (minus pressure) inside the glass cups to make them apply on the desired part of the body. In this review, all types of cupping (i.e. wet cupping, herbal cupping, moving cupping, flash cupping or retained cupping) were included. Primary outcome measures included severity of pain, functional capacity, quality of life (QoL). Secondary outcomes included depression, rate of symptom improvement and adverse effects. There was no limitation on language and publication type.

Identification and selection of studies
We searched China Network Knowledge Infrastructure (CNKI), Chinese Scientific Journal Database (VIP), Wan Fang Database, PubMed, EMBASE, and the Cochrane Library, all the searches ended at March 2017. The search terms included acupuncture-related terms (i.e. “acupuncture”, “acupoint”, “needle”, “electroacupuncture”, “manual acupuncture”, “auricular needling”, “scalp needle”, or “abdominal acupuncture”), combined with cupping-related terms (i.e. “cupping therapy”, “bleeding cupping”, “wet cupping”, “dry cupping”, “flash cupping”, “herbal cupping”, “moving cupping” or “retained cupping”) and pain-related terms (i.e. “ache”, “pain”, “painful”, or “analgesic”). Two authors (XY Yang and BY Lai) selected studies for eligibility and checked against the inclusion criteria independently.
Data extraction and risk of bias assessment
Two authors (YJ Zhang and XL Li) extracted the data from the included studies independently. The methodological quality of RCTs was assessed according to the criteria from the Cochrane Handbook for Systematic Reviews of Interventions [17]. The quality of studies was categorized into low, unclear, or high risk of bias according to the risk for each important outcome within included studies, including adequacy of generation of the allocation sequence, allocation concealment, blinding, whether there were incomplete outcome data and selected reporting the results. Studies which met all criteria were categorized to low risk of bias, studies which meet none of the criteria were categorized to high risk of bias, and those were categorized to unclear risk of bias if insufficient information acquired to make the judgment.
Data analysis
Data were extracted and calculated for frequency using Microsoft Excel 2007 (American: The Microsoft Corporation, 2007). Binary outcomes were summarized using risk ratio (RR) with 95% confidence intervals (CI) for relative effect and risk difference (RD) with 95% CI for absolute effect. The continuous outcomes were summarized using mean difference (MD) with 95% CI. Revman 5.3 (Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboration, 2016) was used for data analyses. Meta-analysis was used if the studies had similar clinical characteristics (such as study design, participants, interventions, control, and outcome measures) and acceptable statistical heterogeneity. Random-effect model was used for meta-analysis. Statistical heterogeneity was detected by I 2 test, an I 2 > 50% indicates the possibility of statistical heterogeneity among the studies. If I 2 was larger than 75%, which means there was obviously statistical heterogeneity among studies, only results from each single study were present respectively rather than pooling analysis. Funnel plot analysis was planned to be generated to detect publication bias.

Trial sequential analysis (TSA)
TSA can be performed if there are more than 5 included studies in the meta-analysis. We applied TSA version 0.9.5.5 (Copenhagen: The Copenhagen Trial Unit, Center for Clinical Intervention Research, 2016) to calculate the required sample size in a meta-analysis and to detect the robustness of the result. We used the diversity-adjusted required information size estimated from a control event proportion of the included studies and a priori intervention effect of 5%, and the diversity which was estimated in the included studies.

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