1. Introduction

Atopic eczema (AE) is a chronic inflammatory skin disease, clinically characterized by exacerbations and remissions of eczematous skin with inflammation, pruritus and excoriations, scaling, dry skin, and susceptibility for cutaneous bacterial and mycotic infections [1]. In the past 30 years, lifetime prevalence has shown a worldwide increase, which plateaus at 10–20% in developed countries and continues to increase in China and many developing countries but lower [2].

The concurrent use of terms such as “eczema,” “atopic eczema,” “atopic dermatitis,” “atopic eczema/dermatitis syndrome,” and “neurodermatitis” has led to confusion and inconsistency in their application. In China, AE is also called as chronic eczema (CE) [3]. Therefore, the nomenclature review committee of the World Allergy Organization has proposed the use of “eczema” as a unifying term, and this term is also used throughout the text of this review [4].

Acupuncture was frequently applied in cases of allergy [5]. In recent years, it has been increasingly utilized as an adjuvant therapy to conventional treatment of eczema [6]. A large number of clinical trials related to acupuncture for eczema have been published in various journals [7]. However, evidence of acupuncture for eczema keeps unclear. The treatment prescriptions are various, and outcome reporting showing heterogeneity makes it impossible to merge data or compare efficacy of different interventions in a systematic review.

The aim of this scoping review is to identify potential treatment prescriptions and compare the outcome reporting for acupuncture clinical trials with the existing core outcome domains developed by the Harmonizing Outcome Measures for Eczema (HOME) consensus, which may help acupuncturists establish potential prioritized treatment prescriptions and choose appropriate outcomes in their future research.

2. Methods

3. Results

3.1. Study Identification

A total of 1332 records were identified from the literature search, and a total of 116 eligible studies were included. The flowchart of the review is shown in Figure 1.

3.3. Results of Data Mining

3.3.1. Frequency Statistics of Acupoints and Meridians

Acupoint frequency was analyzed based on the acquired 116 acupoint prescriptions, which involved 73 acupoints. The top 15 acupoints used frequently were LI11, SP10, ST36, Ashi, SP6, LI4, SP9, BL20, BL13, BL17, GV14, CV4, ST25, PC6, and BL18, in turn. There were 5 acupoints with frequency ≥30, which were Ashi, LI11, SP10, ST36, and SP6. A total of 12 meridians, two extra meridians, and one Ashi point were used in acupuncture for eczema. There are 14 meridians recorded in the 116 acupoint prescription. The top 5 meridians included the Spleen Meridian of Foot-Taiyin (SP), Large Intestine Meridian of Hand-Yangming (LI), Stomach Meridian of Foot-Yangming (ST), Bladder Meridian of Foot-Taiyang (BL), and conception vessel (CV). The most frequently used meridian was SP, which was used 127 times and involved 5 acupoints. Detailed information can be checked in Figure 2.

3.3.2. Common Acupoint Combinations

A total of 15 common acupoint combinations were frequently used over 17 times. There were four acupoint combinations with frequency ≥35: LI11 and SP10, LI11 and ST36, SP10 and ST36, and LI11, SP10, and ST36. The most frequently used acupoint combination was LI11 and SP10, with 58 times. LI11 and ST36 was used 48 times, SP10 and ST36 was used 40 times, and LI11, SP10, and ST36 was used 37 times. Detailed information can be checked in Table 1. The co-occurrence matrix of the 18 acupoints is presented in Figure 3, which were consistent with the common acupoint combinations.

3.3.3. Association Rules of Acupoints

There were 13 acupoint combinations with confidence levels ranging more than 80% and support degree more than 20%, of which SP6, SP10⟶LI11 was listed as the association rules of 96.55%, indicating that when SP6, SP10 was selected, the probability of selecting LI11 was 96.55%. Also, the highest support degree was SP10⟶LI11, which was 54.31%. The association rules for acupoints are described in Table 2. The core acupoint association network of acupuncture for eczema is listed in Figure 4. The degree of support from strong to weak was acupoint LI11 combined with SP10, ST36 with LI11, SP6 with LI11, SP6 with SP10, and LI4 with LI11.

Table 2. Association rules of acupoints.

Number	Acupoints	Confidence level (%)	Support degree (%)
1	SP6, SP10⟶LI11	96.55	25.00
2	SP6⟶LI11	93.94	28.45
3	SP6, ST36⟶LI11	92.59	23.28
4	ST36, SP10⟶LI11	92.50	34.48
5	SP10⟶LI11	92.06	54.31
6	SP6, LI11⟶SP10	90.32	26.72
7	SP6⟶SP10	87.88	28.45
8	ST36⟶LI11	87.27	47.41
9	LI4⟶LI11	85.71	24.14
10	SP6, ST36⟶SP10	85.19	23.28
11	LI4, LI11⟶SP10	83.33	20.69
12	SP6⟶ST36	81.82	28.45
13	SP6, LI11⟶ST36	80.65	26.72

4. Discussion

The meridians, acupoint combinations, and core acupoints identified from the studies included in this scoping review broadly cover the characteristics of acupuncture prescriptions that could be offered in eczema treatment providing antipruritus and anti-inflammatory effect. Acutherapy offers an area for further clinical practice and research for treating eczema.

From the previous systematic review, we found that the majority of clinical trials of acupuncture for eczema are in low methodological quality and quality of evidence [13–15], so it is difficult to draw a definite conclusion. In addition, the researchers and clinicians may use different acupoints, so it is impossible for some clinical trials to include in systematic review when there is heterogeneity in prescription. From the results of data mining, the core acupoints may provide potential prescription to researchers.

This scoping review suggests that specific outcome measures for future clinical trials of acupuncture are clinician-reported signs, patient-reported symptoms, health-related quality of life and long-term control, TCM syndrome, immune system outcomes, and adverse events, which are different form the HOME. In addition, researchers choose different outcome measurement instruments, so some clinical trials will be excluded from systematic reviews, which produce waste and lower the value of research. For acupuncture clinical trials, following the HOME core outcome set for eczema may help improve the consistency of outcomes and outcome measurement instruments.

The theory of TCM is totally different from that of western medicine. When clinicians use acupuncture, the TCM syndromes are important factors that should be considered in the process of treatment and efficacy evaluation. Therefore, in the core outcome set for eczema, TCM syndromes should be considered. In addition, the HOME is developed by stakeholders from developed countries, and the perspectives of professionals and patients from low- and middle-income countries are missed. Therefore, the core outcome set for eczema should be achieved consensus in researchers, clinicians, and patients in China.

The current research had several strengths. To our knowledge, this was the first study that used bioinformatics methods and searched Chinese and English databases to assess which acupoints have been used to treat eczema. First, previous research was limited in that it could only “qualitatively” interpret the characteristics of acupoint prescriptions used in eczema treatment. We overcame this limitation by extracting significant “quantitative” characteristics using the association rule mining. Second, we explored core acupoints used in eczema treatment. Moreover, we evaluated the quality of outcome reporting, OMIs/definitions, and outcome measurement times.

5. Limitations

Our research had several limitations. The present study was based on the frequency of prescription used in the clinical practice and literature. For this reason, we could not evaluate new candidate acupoints emerging from recent experimental studies. Relatedly, we did not evaluate the clinical effectiveness of each prescription and adjunct points prescribed based on syndrome differentiation in our study. Finally, the acupoint combinations and core acupoints of acupuncture for eczema were rarely confirmed by large-scale multicenter clinical trials or animal experiments. Further clinical/experimental studies are needed to assess whether the results derived from our research have real meaning for applications.

6. Conclusions

The preference of core acupoints is LI11, SP10, ST36, SP6, and LI4 in acupuncture clinical studies on eczema. In the future, the researchers could focus on them to prove the efficacy of potential core acupoints. However, researchers should use the core outcome set for eczema to improve the consistency of outcomes and outcome measurement instruments so that the clinical trials will be not exclude from systematic reviews because of the heterogeneity of outcome reporting and outcome measurement instruments.

Conflicts of Interest

The authors declare that they have no conflicts of interest.

Authors’ Contributions

ZZ and ML drafted the manuscript. YZ, JZ, and YL extracted data from articles. ZZ and YZ contributed to the data extracting and assessment. DZ, RQ, and HS revised the manuscript. All authors read and approved the final manuscript.