Psoriasis is a chronic inflammatory skin disease that affects approximately 2–3% of the global population [
1,
2]. It is characterized by epidermal hyperproliferation, abnormal keratinocyte differentiation, angiogenesis with blood vessel dilatation, and excess T-helper cell type 1 (Th1) and Th17 inflammation [
3]. The plaque type is the most common form of psoriasis, accounting for 85–90% of psoriasis cases [
1]; it leads to detrimental physical effects and reduced psychological well-being [
4,
5]. It is also closely related to metabolic syndrome, cardiovascular disease, and chronic obstructive pulmonary disease [
6]. For most patients, psoriasis results in the restriction of various aspects of everyday life, enormous personal costs, and mental stress [
7].
The current treatment for psoriasis primarily comprises local and systemic treatments. Local treatment mainly comprises hormonal drugs and calcineurin inhibitors, and systemic treatment comprises etretin, immunosuppressants, and biological agents [
8]. However, the various side effects and high economic costs limit the clinical application of these treatments [
7]. Therefore, developing or identifying safe and effective treatments for psoriasis has major social and economic benefits.
Recently, complementary and alternative medicine (CAM) therapies have become an increasingly important area of dermatology, and cupping is becoming an important CAM therapy. Cupping is an ancient method that has been used worldwide. From ancient Egypt to the Han Dynasty in China [
9,
10], and from Hippocrates in Greece to the early Islamic period [
11,
12], there have been numerous descriptions of cupping treatments for various diseases. Cupping is currently used to treat a wide range of medical conditions [
13,
14], and randomized controlled trials (RCTs) have confirmed the efficacy of cupping for certain pain-related diseases such as osteoarthritis of the knee and chronic low back pain [
15,
16]. There are two types of cupping methods; dry and wet. Moving cupping therapy is a unique dry method that has been used as a traditional treatment for thousands of years. This method involves the application of lubricant to the body part or to the mouth of the cup and using the flashing method or the cotton sticking method to adsorb the cup to the treatment area. The cotton sticking method involves pasting cotton soaked in alcohol on the inner wall of the cup; it is then ignited and adsorbed on the treatment area, but the skin may be scalded due to the excessive dripping of alcohol. The flashing method quickly withdraws the cotton soaked in alcohol. This is a safe and common method of cupping. The physician pushes the cup by hand to move it up and down and left and right, thus causing flushing, congestion, and even ecchymosis of the skin in the treatment area [
17]. Therefore, moving cupping therapy integrates the functions of warm moxibustion (which involves lighting the moxa stick and hanging it at a certain distance from the skin), cupping, scraping, massage, and drug therapy, and it has a wide range of clinical applications. This therapy has the ability to regulate immune function [
18,
19], thereby improving skin tolerance [
20,
21]. Psoriasis damages the epidermis, which destroys the human skin barrier composed of keratinocytes, intercellular substance, natural moisturizing factors, and sebum membranes. The Koebner phenomenon illustrates the important relationship between an impaired skin barrier and psoriasis [
22,
23]. Moving cupping treatment can cause the mechanical stimulation of pulling and is beneficial for the secretion of sebaceous glands and sweat glands, and the use of lubricants can significantly improve the skin barrier function. Psoriasis is also known to be closely related to lipid metabolism [
24]. Cupping therapy can upregulate anti-inflammatory lipids, downregulate the function of pro-inflammatory lipids, improve the balance of lipid metabolites, and alleviate the inflammatory response [
25].
Moving cupping therapy has been widely used for the treatment of plaque psoriasis, which is safe and associated with few adverse reactions, mainly local blisters. Additionally, it has been recognized by a large number of peers and patients. One study compared the efficacy of moving cupping and narrowband ultraviolet B based on oral Chinese herbs and found that moving cupping has clear advantages, but lacked high-quality medical evidence [
26]. Therefore, we designed a multicenter, prospective, single-blind, placebo-controlled, RCT to evaluate the safety and efficacy of moving cupping therapy for plaque psoriasis.
Objectives and hypotheses
Moving cupping is widely used as a CAM therapy. The aim of this RCT is to evaluate the efficacy of moving cupping as a plaque psoriasis treatment. The hypothesis of this study is that the Psoriasis Area and Severity Index (PASI), used as the primary endpoint to demonstrate the clinical efficacy of plaque psoriasis treatment, will be decreased significantly with moving cupping treatment compared to placebo treatment [
27]. Secondary endpoints, including body surface area (BSA), Physician’s Global Assessment (PGA), Traditional Chinese Medicine syndrome scoring scale (TCMSSS), and patient-reported outcomes (Dermatology Life Quality Index [DLQI] and visual analogy scale [VAS]), for the evaluation of post-treatment clinical efficacy, psychology, quality of life, and degree of pruritus will also be considered. This study complies with the relevant Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) Checklist (Supplementary file
1) [
28].