A bibliometric analysis offers a valuable opportunity to identify potential gaps in the literature, to quantitatively evaluate academic literature, providing insights into research trends, influential authors which can, in turn, guide future research efforts [25]. To the best of our knowledge, this is the first bibliometric analysis focused on the topic of mixed pain. Therefore, the results from this study could be highly beneficial for shaping and ultimately directing further research in the field.

Given the complexity and clinical relevance of mixed pain, our study aimed to conduct a comprehensive bibliometric analysis to enhance understanding of this topic. Our analysis revealed a progressive increase in the number of publications on mixed pain from 1993 to 2024, indicating growing interest in this area. This upward trend was particularly pronounced from 1993 to 2023, with a significant APC in the number of publications.

Concerning the quality of the journals, most documents were published in highly ranked Q1 journals, and the journal “Pain Practice” published 12 papers, followed by “Clinical Journal of Pain” that published 8 articles. Analyzing sources is beneficial for authors as it aids in searching the literature and selecting an appropriate journal for submitting their articles. The progressive increase in the number of citations over time highlights the visibility of these articles, although this increase is not necessarily indicative of their quality [26]. However, it reflects the interest in the topic of mixed pain, as evidenced by the types of published papers: research articles (77%) and review articles (19%). These factors suggest an overall high level of research quality.

The co-authorship analysis for countries highlighted the central role of certain countries in mixed pain research. The USA emerged as a dominant contributor, accounting for 21% of the total publications, followed by Italy and Germany. The co-authorship analysis for countries further emphasized the USA acting as a central hub in international collaborations. Unfortunately, despite its significant publication output, Italy appeared relatively isolated, with limited connections to other countries. As previously observed in the publication patterns of Italian sociologists, this isolation effect may be linked to the distorting influence of institutional signals on publication choices. Italian sociologists have been known to publish more frequently in journals considered influential for assessment purposes, but often without engaging in an international collaborative network [27]. This suggests potential opportunities for enhancing international collaboration in mixed pain research, particularly involving countries with high research output (USA, Italy, Canada, Brazil, Germany, England, and Australia). In addition to geographical trends, the analysis of co-authorship among individual authors revealed the influence of key publications in shaping the field. The works of Freynhagen et al. [22, 23], were identified as significant nodes within the citation network, indicating their impact on subsequent research. In fact, their publication of 2019 discussed the concept of “mixed pain”, which is increasingly used to describe clinical scenarios such as low back pain, cancer pain, and postsurgical pain, where different types of pain (nociceptive, neuropathic, and nociplastic) overlap and cause pain in the same area [23]. They highlighted whether mixed pain is due to these mechanisms operating simultaneously or if it represents a distinct pathophysiological process. In fact, the diagnosis of mixed pain relies on clinical judgment rather than formal screening or diagnostic criteria, which poses challenges for pain physicians. The authors proposed also a methodical approach for evaluating patients with acute, subacute, or chronic pain, including nine key questions to help clinicians identify the predominant pain mechanisms [28]. However, despite its extensive use in the literature, the term “mixed pain” has never been formally defined even if it is increasingly recognized and accepted by pain clinicians to describe these complex cases.

The keyword analysis in our bibliometric study highlighted the importance of terms such as “neuropathic pain,” “management,” and “quality of life” within the field of mixed pain research. “Neuropathic pain” emerged as a central focus, reflecting also its role as a component of mixed pain. This highlights the ongoing interest in understanding and addressing the complex mechanisms underlying neuropathic pain, which is notoriously difficult to treat [24]. A significant portion of our current knowledge about the causes of neuropathic pain and the identification of drug targets comes from studies examining the effects of peripheral nerve injury in rodent models [29, 30]. While traditional animal models have uncovered critical aspects of pain etiology, including peripheral and central sensitization and various molecular and cellular mechanisms, they fall short in capturing the full range of disease states or injuries that lead to neuropathic pain in clinical settings. Consequently, translating findings from the lab to effective clinical treatments has achieved only limited success [31, 32]. There is an urgent need to find new treatments for neuropathic pain and combination therapies such as drug-drug co-crystallization may represent a potential therapeutic approach to target the multiple mechanisms of neuropathic pain [33].

Directly related to mixed pain and neuropathic pain is the keyword “management”. This underscores the need for effective strategies to treat mixed pain. As highlighted in the Latin American consensus meeting on mixed pain, the emphasis was placed on the importance of multidisciplinary approaches in achieving optimal patient outcomes [11]. Moreover, the Latin American consensus highlighted the potential role of vitamins B1, B6, and B12, whether used alone or as an adjunct to other analgesic drugs, in the management of mixed pain, based on positive findings from both preclinical and clinical studies on nociceptive and neuropathic pain [34,35,36,37,38]. Unfortunately, despite the promising potential of this approach, there are currently no studies specifically focused on exploring the role of B vitamins in the management of mixed pain.

Additionally, the frequent occurrence of “quality of life” as keyword indicates a growing recognition of the broader impact of pain on patients’ overall well-being. The evaluation of the impact of pain on quality of life was clearly recommended by the IASP [1] and explored in neuropathic and cancer pain [39]. However, no specific studies have addressed the quality of life in mixed pain patients compared to those with nociceptive, neuropathic or nociplastic pain. This gap in the research highlights the need for future studies to develop a formal definition of mixed pain, explore the quality of life in individuals with mixed pain, and investigate any unique characteristics that may differentiate them from other pain populations.

The keyword analysis provided a valuable method for identifying key themes in mixed pain and establishing a framework of relevant documents within this field of research. Unfortunately, only five clusters were identified, indicating a lack of cohesion among keywords, which are dispersed across a wide range of scientific papers. This suggests that the research on mixed pain is still fragmented and lacks unified focus.

This analysis has several limitations. The search and methods were confined to articles extracted and analyzed from the WoSCC database, which may have led to the exclusion of articles available in other databases (e.g., Scopus or PubMed) or in the grey literature. Although WoSCC was chosen due to its widespread use in bibliometric studies [40], this limitation should be considered when interpreting the results. Furthermore, as Gasparyan et al. [41] recently suggested, the significance of article metrics should be evaluated while considering confounding factors, such as citation patterns and social media engagement across different countries and academic disciplines. In fact, external factors that are not fully understandable can influence citations, keywords and authors patterns. Another limitation of our study is that we did not perform a Price index analysis. The Price index, based on Price’s Law, is widely used to assess the growth trends of scientific outputs within a specific country or academic discipline [42]. It helps determine whether the increase in publications follows an exponential or linear pattern. However, given our findings regarding the international distribution of research on mixed pain, where research efforts are fragmented and collaborative networks are limited, we opted not to perform this analysis. The diverse and uneven contributions from different countries in the field of mixed pain could have led to skewed results, making the Price index less applicable in this context. Another potential limitation is the search string we used for the bibliometric analysis, as it may have been incomplete or not exhaustive in capturing all published articles on this topic. However, the large number of articles initially extracted from WoSCC, many of which were later excluded due to being non-pertinent or duplicates, suggests that our search strategy was effective in comprehensively identifying relevant indexed papers. This process likely ensured that most of the pertinent literature was included in our analysis. Finally, the rise in publications found in our analysis should be considered in the context of the overall growth in publications indexed in WoSCC and also the increase in mixed pain research may be influenced by this general trend [43]. Consequently, this analysis should be updated periodically.

The primary goal of a bibliometric study is to provide guidance and recommendations for future research. Given the current landscape of mixed pain research, several key areas warrant further exploration. Firstly, there is an urgent need for a formal definition of mixed pain, along with the development of diagnostic criteria and specific guidelines to aid clinicians in accurately identifying and managing this complex condition. Additionally, due to the limited group characteristics observed in cooperative networks, it appears that authors tend to publish independently. These results highlight the need to strengthen international partnerships and collaboration to foster more balanced and cohesive progress in the field of mixed pain. Future studies should also be focused on investigating the role of vitamins B1, B6, and B12 in mixed pain management, building on the promising results seen in nociceptive and neuropathic pain. The quality of life and the presence of comorbidities in patients with mixed pain remain underexplored, particularly in comparison to those with purely nociceptive or neuropathic pain. Research in this area could uncover unique characteristics that may guide more tailored treatment approaches. Moreover, enhancing international collaboration is essential to address the current fragmentation in the field, as evidenced by the dispersed keyword clusters and limited cooperative networks. By strengthening partnerships and fostering more cohesive research efforts, the global understanding and treatment of mixed pain can be significantly advanced.