Abstract

Introduction: Headache disorders are among one of the most common nervous system disorders affecting approximately 50% of adults worldwide. Acupuncture is a therapy originating from traditional Chinese medicine; some research has suggested that its use may relieve headache disorders. The objective of the present bibliometric analysis is to capture the characteristics of peer-reviewed publications at the intersection of headache and acupuncture research.

Methods: Searches were run on July 08, 2021, and results were exported on the same day to prevent discrepancies between daily database updates. Trends associated with this subset of publications were identified and presented. Bibliometric networks were constructed and visualized using the software tool VOSviewer.

Results: A total of 592 publications, published by 1482 authors were published in 231 journals from 1965 to 2021. An upward trend in the annual number of publications can be observed starting in the mid-1970s. The journal that published the largest number of publications was Deutsche Zeitschrift Fur Akupunktur. The most productive countries included China and Germany.

Conclusions: The present study provides the characteristics of the literature at the intersection of headache disorders and acupuncture that allows understanding of the past, present, and future of research in this area.

Background

Headache disorders are among one of the most common nervous system disorders affecting approximately 50% of adults worldwide [1–2] and are classified into two categories: primary and secondary. Primary headache disorders are not caused by underlying medical conditions and are believed to have a genetic etiology; these include migraine, tension-type headache, cluster headache, and chronic daily headache syndrome [3]. Migraines are the most prevalent and debilitating primary headache disorder, affecting an estimated 959 million people globally [4]. In comparison, secondary headache disorders are caused by underlying medical conditions such as head and/or neck trauma, vascular issues, intracranial disorders, epileptic seizures, substance use, and intracranial infection. Secondary headaches are only diagnosed if the headache subsides following the elimination of the underlying disorder; otherwise, a diagnosis of a primary headache disorder is given [5]. Headache disorders are often diagnosed following examination by primary care physicians or neurologists and are guided by criteria outlined in the International Classification of Headache Disorders [3]. Conventional treatments for headache disorders are typically heavily reliant on pharmaceutical medications, however, in many cases, these only mask the symptoms for a period of time only to reoccur later [6]. Many patients turn to over-the-counter medications such as acetaminophen, however, the American Headache Society strongly recommends that over-the-counter medications are used no more than 2 days per week [6]. As a result of the side-effects and limited period of relief associated with pharmaceutical medications, many individuals suffering from headache disorders also seek out complementary, alternative, and integrative/integrated medicine therapies, such as acupuncture, believing that such therapies are effective [7–8].

Acupuncture, a traditional Chinese medicine technique that involves stimulating precise points on the body by penetrating the skin with thin, metallic needles [9], is a therapy commonly used by those suffering from headache disorders. The research on acupuncture use for headache disorders is varying and emerging, however, there is growing evidence supporting its use as a promising treatment for headache disorders. A 2017 review of systematic reviews and meta-analyses summarizing the efficacy of acupuncture for various conditions identified acupuncture as an effective treatment for 8 conditions, including migraine prophylaxis, chronic tension-type and chronic episodic headache [10]. A systematic review investigating the effectiveness of acupuncture in protecting against episodic migraines found that a course of at least six acupuncture treatment sessions were as effective as prophylactic pharmaceuticals in reducing their frequency [11]. The review also found that this six-course acupuncture treatment showed a small, but significant reduction in migraine frequency following both treatments and after median follow-up intervals of 12 weeks to 6 months when compared against sham acupuncture treatment [11]. Another review investigated the therapeutic and preventative effects of acupuncture use for migraine without aura; the authors found that acupuncture provided a substantial benefit over sham acupuncture and oral medications such as propranolol, ibuprofen, flunarizine, and nimodipine in terms of lowering migraine frequency and visual analogue scale (VAS) score. [12]. A meta-analysis of randomized controlled trials exploring the efficacy of manual acupuncture for migraines found that it had a greater total effective rate than sham acupuncture, but no significant differences were found in migraine intensity, frequency, or duration, associated symptoms, or medication use [13]. A study investigating the effectiveness of acupuncture for the prevention of tension-type headaches and reported that when acupuncture was compared with standard acute headache treatment, the proportion of participants who experienced a 50% reduction in headache frequency was substantially higher in the acupuncture groups than in the control groups [14]. When acupuncture was compared with sham acupuncture, 51% of those who received acupuncture experienced a 50% reduction in headache frequency, compared to 43% in the sham group [14]. A systematic review found acupuncture to be superior to sham acupuncture in patients with migraine and tension-type headache, with a significantly greater response rate and a considerable reduction in headache intensity at the late follow-up period. [15]. In light of all of the recent research exploring the efficacy of acupuncture for various chronic disorders, a bibliometric analysis is necessary to consolidate the historical development and arising trends at the research intersection of acupuncture therapy and headache disorders

A bibliometric analysis is a statistical evaluation of scientific publications used to discover characteristics and evaluate the impact of literature produced in a particular academic area. A number of bibliometric analyses have been conducted to uncover the research trends at the intersections of acupuncture and insomnia [16] and acupuncture and cancer [17], however, to our knowledge, no bibliometric analysis have previously summarized the literature at the intersection of acupuncture and headache disorders and migraine. Therefore, the present study includes a bibliometric analysis of global research trends at the intersection of acupuncture and headache disorders and migraine. This study’s findings provide characteristics and trends associated with the literature published at the intersection of acupuncture and headache disorders.

Methods

The following search was run on the Scopus database on July 08, 2021, as follows: “((TITLE(( "headache*" OR "migraine*" OR "cephalgi*" )) AND TITLE(( "acupunctur*" OR "acupressur*" OR "dry needl*" )))”. The data search and search results were conducted and exported on the same day to circumvent differences in results due to database updates. AF and JYN manually screened all articles to determine eligibility. All documents included in the study were literature published at the intersection of acupuncture or acupressure or dry needling and migraines and/or headache disorders and all associated conditions. Literature that mentioned acupuncture but did not mention headache disorders, or vice versa, were excluded. The authors did not place any restrictions on article type or language of publication.

The following data was collected and reported: total number of publications, open access status, most common funding sponsors, and institutional affiliations; most highly published authors and their H-Index, country of publication, publication language, publication type, publication subject area, publication year, and most highly-cited publications; most highly productive journals, if the literature was published in an acupuncture focused journal, a CAIM-focused journal, or a journal with other research focuses, and 2020 journal impact factor. Journal impact factors according to the InCites Journal Citation Reports were included [18].

We also constructed bibliographic networks using the software VOSviewer [19]. Using the visualization of similarities (VOS) technique, this software has the capacity to create maps of co-authorship, journals, or countries based on co-citation networks, and can even chart keywords based on co-occurrence data [19]. This software allowed for easy analysis and visualization of relationships between publications, at the level of co-authorships, institutional affiliations, and keyword usage. In a network visualisation, each item (e.g., publications, researchers, keywords) in a bibliometric map is illustrated by a label and a circle. The size of an items label and circle are determined by its weight, a measure of its importance.

Results

The search strategy yielded 592 results, however, two articles were excluded as they were not focused on the intersection of acupuncture and headache disorder use or headache disorder associated conditions. 590 documents (124 open access) at the intersection of acupuncture or acupressure and migraines and/or headache disorders and all associated conditions were published between 1965 and 2021 and included in this study (Fig. 1). An upward trend in the annual number of publications can be observed starting in the mid-1970s. A sharp increase in the publication volume is seen from 2002 to 2005, which is followed a steep decrease in publications over the next two years. However, publication volumes did recover shortly after and remained stable from 2009 to 2019. The year 2020 saw the greatest volume of publications in a year to date, with 39 publications.

Medicine was the subject area with the greatest volume of publications (n = 548), followed by neuroscience (n = 65) and health professions (n = 29). Most papers were published in English (n = 428), followed by German (n = 78) and Chinese (n = 50). The three most productive countries included China (n = 147), Germany (n = 97), and the United States (n = 84). Chengdu University of Traditional Chinese Medicine (n = 31), Technical University of Munich (n = 21), and Charité – Universitätsmedizin Berlin (n = 18) were the 3 most common institutional affiliations; The National Natural Science Foundation of China (n = 21), the National Institutes of Health (n = 12), and the United States Department of Health and Human Services (n = 12) were the most common funding sponsors. Nine document types were identified within the 590 included documents. Articles (n = 405) and reviews (n = 60) were the most frequently used document type, respectively representing 68.60% and 10.17% of the total documents. The general characteristics of documents published in all journal types can be found in Table 1.

Deutsche Zeitschrift Fur Akupunktur (n = 26), Cephalalgia (n = 22) and Zhongguo Zhen Jiu Chinese Acupuncture Moxibustion (n = 22) published the greatest number of papers on the use of acupuncture for headache and/or migraine relief, of all journals, regardless of research focus (Table 2). Of the 14 most productive journals, five were acupuncture focused, two were focused on headache-disorders, five were CAIM-focused, and two were dedicated to areas of research outside of acupuncture, headache-disorders, and CAIM. The 15 authors with the most publications are listed in Table 3. Table 4 lists the 15 most cited publications across all journals.

Figure 2 illustrates a co-authorship analysis of the 17 most productive countries. In a co-authorship analysis, the relatedness of items is determined by the number of documents that are shared by the authors. From this figure, one can see that the United States, Germany, and China are the 3 most productive countries, however, their collaboration trends vary. American and Chinese authors tend to collaborate with a wider range of international authors, as the United States (n = 13) and China (n = 12) are shown to have the greatest number of links to other countries (n = 13). Meanwhile, German authors tend to collaborate more closely with other European authors.

Figure 3 illustrates a co-occurrence analysis of the 27 most frequently used author keywords. In a co-occurrence analysis, items’ relatedness is determined by the number of documents in which they occur together. As expected, acupuncture, headache, and migraine are the largest items, as they are the most frequently used author keywords. The varying colours of the items illustrate different clusters of keywords: keywords in the blue and green clusters are related to various therapies and headache disorders, while keywords in yellow and red are related to review-type research and clinical research.

Discussion

The objective of this study was to investigate the publication history and research trends at the intersections of acupuncture and headache disorders. Since the 1970s there has been a general increase in the annual number of publications, with a major increase in the published literature per annum observed in the early to mid-2000s. The rising trend in annual publications has continued to the present as 2020 was the year with the greatest number of publications in a year to date. The increasing number of publications over the years also reflects the growing global research interest at the intersections of acupuncture and headache disorders.

In this study, China, Germany, and the United States were the three most productive countries. China has been an acupuncture authority for decades, as the birthplace of acupuncture and many other traditional Chinese medicine (TCM) treatments which are integral to its medical culture. With the increasing global interest in TCM and CAIMs for various conditions, such as cancer [17] and insomnia [16], the nation has continued to conduct a number of clinical trials exploring the efficacy of TCMs and has recently launched the Action Plan of Regulatory Science which will aims to advance regulatory tools and standards used to evaluate TCM safety research [20]. Acupuncture has become increasingly popular in the United States over the years [21] as it is now the 11th most commonly used complementary health therapy [22]. Potential factors contributing to this trend include the increasing costs of conventional healthcare in the United States, continued research into the efficacy of acupuncture, and the inclusion of acupuncture in private health insurance plans [21]. Beginning in 2001, a series of German acupuncture trials investigating the cost-effectiveness, safety, and usefulness of acupuncture as a treatment for chronic back pain, osteoarthritis, migraine prophylaxis, and tension-type headache [23]. The results found acupuncture to be an effective, economical treatment for the aforementioned conditions. Following the studies’ success, Germany began covering the costs of acupuncture therapy for chronic back pain and osteoarthritis under public health insurance, opening the door for many more Germans to undergo acupuncture treatment [23].

Unsurprisingly, the 3 most common languages of publication were English, German, and Chinese as this reflects the three most productive nations. Of the top 10 institutional affiliations, 5 were Chinese, 3 were German, 1 was Italian, and 1 was American. The top 10 funding sponsors were split between China and the United States, with 6 Chinese sponsors and 4 American sponsors.

A number of caveats should be considered when interpreting the results of this study. Firstly, a greater number of publications and research collaborations will be found among authors with longer research careers; these authors will also have a greater volume of their research indexed in Scopus. Likewise, older publications will have a higher likelihood of receiving more citations, as indicated by the fact that 13 of the top 15 cited publications were written in or after 2009. Future research should continue to investigate changes in the publication characteristics of emerging literature published at the intersection of acupuncture and headache disorders.

Conclusion

This bibliometric analysis investigated and mapped publication trends at the intersection of acupuncture and migraine and/or headache disorders and all associated conditions. Co-occurrence analyses of keywords and co-authorship analyses by country were mapped with VOSviewer. China, Germany, and the United States were the most productive countries, collectively accounting for over 50% of the total documents included in this study. Unsurprisingly, most institutional affiliations and funding sponsors were from these three countries. There was a positive trend in the annual number of publications which began in the 1970s. With 39 publications, 2020 has been the year with the most publications to date. As this study presented keyword networks, collaboration history, and publication trends, many of these results may help researchers identify new directions for future authorship and institutional partnerships.

Declarations

Ethics Approval and Consent to Participate

This study involved a bibliometric analysis of the literature only; it did not require ethics approval or consent to participate.

Consent for Publication

The authors consent to this manuscript’s publication.

Availability of Data and Materials

All data generated or analysed during this study are included in this published article.

Competing Interests

The authors declare that they have no competing interests.

Funding

This study was unfunded.

Authors' Contributions

JYN: conceptualized and designed the study, collected the data, interpreted and analysed the data, co-drafted the manuscript, and gave final approval of the version to be submitted.

AF: collected the data, interpreted and analysed the data, co-drafted the manuscript, and gave final approval of the version to be submitted. 

Acknowledgements 

JYN was awarded a Research Scholarship and an Entrance Scholarship from the Department of Health Research Methods, Evidence and Impact, Faculty of Health Sciences at McMaster University.

References

1. Ahmed F. Headache disorders: differentiating and managing the common subtypes. BJP. 2012 Aug; 6(3): 124–32. https://doi.org/10.1177/2049463712459691.
2. World Health Organization. 2016. [Internet]. Headache Disorder: Fact Sheet. [cited 2021 May 24]. Available from: https://www.who.int/en/news-room/fact-sheets/detail/headache-disorders/.
3. Olesen J. Headache Classification Committee of the International Headache Society (his) the international classification of headache disorders, asbtracts. Cephalalgia. 2018 Jan;38(1):1–211. https://doi.org/10.1177/0333102417738202.
4. GBD 2015 Disease and Injury Incidence and Prevalence Collaborators (2016). Global, regional, and national incidence, prevalence, and years lived with disability for 310 diseases and injuries, 1990–2015: a systematic analysis for the Global Burden of Disease Study 2015. Lancet (London, England), 388(10053), 1545–1602. https://doi.org/10.1016/S0140-6736(16)31678-6.
5. Schankin CJ, Straube A. Secondary headaches: secondary or still primary?. The journal of headache and pain. 2012 Jun;13(4):263 – 70. Schankin, C. J., & Straube, A. (2012). Secondary headaches: secondary or still primary?. The journal of headache and pain, 13(4), 263–270. https://doi.org/10.1007/s10194-012-0443-8.
6. Loder E, Weizenbaum E, Frishberg B, Silberstein S. American Headache Society Choosing Wisely Task Force. Choosing Wisely in Headache Medicine: The American Headache Soci’ty's List of Five Things Physicians and Patients Should Question. Headache. 2013 Nov;53(10):1651–9. https://doi.org/10.1111/head.12233.
7. Jong MC, van de Vijver L, Busch M, Fritsma J, Seldenrijk R. Integration of complementary and alternative medicine in primary care: what do patients want? Patient education and counseling. 2012 Dec;89(3):417–22. https://doi.org/10.1016/j.pec.2012.08.013.
8. Lambert TD, Morrison KE, Edwards J, Clarke CE. The use of complementary and alternative medicine by patients attending a UK headache clinic. Complementary therapies in medicine. 2010 Jun 1;18(3–4):128 – 34. https://doi.org/10.1016/j.ctim.2010.05.035.
9. Kaptchuk TJ. Acupuncture: theory, efficacy, and practice. Annals of internal medicine. 2002 Mar 5;136(5):374 – 83. https://doi.org/10.1002/14651858.CD001218.pub2.
10. McDonald J, Janz S. Australian Acupuncture and Chinese Medicine Association. 2017. [Internet]. The acupuncture evidence project: A comparative evidence review. [cited 2021 May 28]. Available from: https://www.acupuncture.org.au/wp-content/uploads/2017/04/.
11. Linde K, Allais G, Brinkhaus B, Fei Y, Mehring M, Vertosick EA, Vickers A, White AR. Acupuncture for the prevention of episodic migraine. Cochrane Database of Systematic Reviews. 2016(6). 10.1002/14651858.CD001218.pub3.
12. Xu J, Zhang FQ, Pei J, Ji J. Acupuncture for migraine without aura: a systematic review and meta-analysis. Journal of integrative medicine. 2018 Sep 1;16(5):312 – 21. 10.1016/j.joim.2018.06.002.
13. Yang Y, Que Q, Ye X, Zheng GH. Verum versus sham manual acupuncture for migraine: a systematic review of randomised controlled trials. Acupuncture in Medicine. 2016 Apr;34(2):76–83. 10.1136/acupmed-2015-010903.
14. Linde K, Allais G, Brinkhaus B, Fei Y, Mehring M, Shin BC, Vickers A, White AR. Acupuncture for the prevention of tension-type headache. Cochrane Database of Systematic Reviews. 2016(4). 10.1002/14651858.CD007587.pub2.
15. Sun Y, Gan TJ. Acupuncture for the management of chronic headache: a systematic review. Anesthesia & Analgesia. 2008 Dec 1;107(6):2038-47. 10.1213/ane.0b013e318187c76a.
16. Pei W, Peng R, Gu Y, Zhou X, Ruan J. Research trends of acupuncture therapy on insomnia in two decades (from 1999 to 2018): a bibliometric analysis. BMC complementary and alternative medicine. 2019 Dec;19(1):1–9. 10.1186/s12906-019-2606-5
17. Guo J, Pei L, Chen L, Chen H, Gu D, Xin C, Peng Y, Sun J. Research Trends of Acupuncture Therapy on Cancer Over the Past Two Decades: A Bibliometric Analysis. Integrative cancer therapies. 2020 Nov;19:1534735420959442.
18. Clarivate Analytics. (2020). InCites Journal Citation Reports. https://jcr.clarivate.com/)
19. Van Eck NJ, Waltman L. Software survey: VOSviewer, a computer program for bibliometric mapping. Scientometrics. 2010 Aug;84(2):523–38.
20. The Center People’s Government of the PRC. NMPA has initiated the “Action Plan on Regulatory Science in China. [cited 2021 Jul 20]. http://www.gov.cn/xinwen/2019-05/02/content_5388253.htm.
21. Austin S, Ramamonjiarivelo Z, Qu H, Ellis-Griffith G. Acupuncture use in the United States: who, where, why, and at what price?. Health marketing quarterly. 2015 Apr 3;32(2):113 – 28. https://doi.org/10.1080/07359683.2015.1033929.
22. Clarke TC, Black LI, Stussman BJ, Barnes PM, Nahin RL. Trends in the use of complementary health approaches among adults: United States, 2002–2012. National health statistics rep.
23. Cummings M. Modellvorhaben Akupunktur–a summary of the ART, ARC and GERAC trials. Acupuncture in Medicine. 2009 Mar;27(1):26–30. https://doi.org/10.1136/aim.2008.000281.
24. Zhao T, Guo J, Song Y, Chen H, Sun M, Chen L, Geng H, Pei L, Sun J. A Bibliometric Analysis of Research Trends of Acupuncture Therapy in the Treatment of Migraine from 2000 to 2020. Journal of Pain Research. 2021;14:1399. 10.2147/JPR.S306594.
25. Zhao Y, Huang L, Liu M, Gao H, Li W. Scientific Knowledge Graph of Acupuncture for Migraine: A Bibliometric Analysis from 2000 to 2019. Journal of Pain Research. 2021;14:1985. https://doi.org/10.2147/JPR.S314174.
26. Haiqi, Z. Basic Literature of Acupuncture in Medline: A Bibliometric Analysis. Libri. 1995 Jun 1; 45(2): 113–122.
27. Lee IS, Lee H, Chen YH, Chae Y. Bibliometric analysis of research assessing the use of acupuncture for pain treatment over the past 20 years. Journal of Pain Research. 2020;13:367. 10.2147/JPR.S235047.
28. Birch S, Lee MS, Alraek T, Kim TH. Overview of treatment guidelines and clinical practical guidelines that recommend the use of acupuncture: a bibliometric analysis. The Journal of Alternative and Complementary Medicine. 2018 Aug 1;24(8):752 – 69. 10.1089/acm.2018.0092
29. Robert C, Wilson CS, Lipton RB, Arreto CD. Growth of headache research: a 1983–2014 bibliometric study. Cephalalgia. 2017 Nov;37(13):1299–309. 10.1177/0333102416678636
30. AlRyalat SA, Malkawi LW, Momani SM. Comparing bibliometric analysis using PubMed, Scopus, and Web of Science databases. JoVE (Journal of Visualized Experiments). 2019 Oct 24(152):e58494. 10.3791/58494.
31. Mongeon P, Paul-Hus A. The journal coverage of Web of Science and Scopus: a comparative analysis. Scientometrics. 2016 Jan 1;106(1):213 – 28. https://doi.org/10.1007/s11192-015-1765-5.

Tables

Table 1: General Characteristics of Publications at the Intersections of Acupuncture and Migraine and/or Headache Disorders and All Associated Conditions 

Table 2: 14 Most Productive Journals across All Research Focuses

Table 3: 15 Most Productive Authors 

Table 4: 15 Highest-Cited Publications across All Journals