A bibliometric analysis of self‐efficacy in low back pain from 1980 to 2021

Self‐efficacy is one of the important factors affecting chronic diseases. In the current epidemiological context of low back pain (LBP), LBP self‐efficacy has become a topic of great practical interest for researchers. However, no bibliometric analysis related to LBP self‐efficacy has been performed to date. The purpose of this study was to conduct and explore the current state of research in LBP self‐efficacy from 1980 to 2021, by using bibliometric analysis and scientific mapping.


I N T RODUC T ION
Low back pain (LBP) is a very prevalent ailment problem that almost everyone will have in their lives. 1 It is the largest cause of years lived with disability. 2 At the same time, LBP poses a greater medical and financial burden around the world. 3,4 More attention is urgently required to alleviate the growing strain and its impact on health and social systems. 5,6 Self-efficacy was defined by Bandura in 1977 as the belief that one can effectively execute a course of action in a particular scenario to create a desired result. 7,8 In a later study, Bandura suggested that self-efficacy underlies many health-related behaviors and therefore may be important in the area of chronic diseases. 9 Because of the epidemiological elements of LBP, researchers have refined the studies in recent years, and while some studies have examined self-efficacy in relation to LBP, 7,10 there are no large-scale bibliometric analyses of self-efficacy for LBP.
Bibliometrics is a quantitative method to analyze data and evaluate research. 11 In numerous multidisciplinary investigations, tracking knowledge dissemination and utilizing cluster analysis can offer a thorough summary. [12][13][14][15] CiteSpace is a scientific mapping software developed by Chen and his team (Drexel University, Philadelphia, PA, U.S.A.) based on Java language environment background, which can do bibliometric analysis and comparative analysis. 16 It has been used in a number of disciplines, including regenerative medicine, 17 cytology, 18 health care, 19 and environmental science 20,21 Based on this, CiteSpace can be used through bibliometrics to explore the specific characteristics of the field.
The purpose of this study was to fill the gaps in current bibliometric studies of LBP self-efficacy by systematically exploring developments, trends, and the current state of the research field between 1980 and 2021. The Web of Science (WOS) database was used as a source for literature analysis to uncover relationships between the literature and to provide more useful information for the future researchers.

Data source
All the data of this study were based on Web of Science Core Collection (WOSCC), includes Social Sciences Citation Index (SSCI), Science Citation Index Expanded (SCI-Expanded), and Emerging Sources Citation Index (ESCI). Literature retrieval was performed in 1 day (January 5, 2022). The search strategy was as follows: TI = (low back pain OR low back ache OR sciatic* OR lower back pain OR lower back ache OR low backache OR backache OR back pain) AND TI = (self manage* OR self-manage* OR self aware* OR self-aware* OR knowledge* OR self control OR self-control OR perception* OR cognitive* OR autogenic OR self-efficacy OR self efficacy OR efficacy OR auto suggestive OR autosuggestion). The time of the publication was limited from 1980 to 2021 ( Figure 1).

Inclusion and exclusion criteria
The included publications meet the following criteria: (1) literature topic is LBP; (2) the specific research interests are related to self-management and self-awareness; (3) literature published between 1980 and 2021; (4) literature index from WOSCC, SSCI, SCI-Expanded, and ESCI. There were 1155 papers collected on January 5, 2022. Exclusion criteria: (1) articles not officially published; (2) conference abstracts and proceedings, corrigendum documents. Of these records, the data were cleaned to remove duplicate literature through CiteSpace, resulting in the effective inclusion of 822 publications.

Analysis tools
There were three software programs used for data organization, analysis, and visualization; CiteSpace 5.8.R3 (Drexel University, Philadelphia, U.S.A.), Microsoft Excel 2019, and IBM SPSS 25.0 (SPSS Inc, Chicago, U.S.A.). CiteSpace 5.8.R3 is a java language-based information visualization software, built up on co-citation analysis theory and pathfinder network scaling. It measures the literature in specific fields, explores key paths and knowledge turning points in the evolution of subject, and completes the analysis of potential dynamics of subject evolution and detection about subject development frontiers through a series of visual maps. 16 In CiteSpace, the evaluation of the mapping is effected by modularity F I G U R E 1 Flow chart of data processing. Q value (Q value) and mean silhouette values (S value). When Q value > 0.3, it means that the structure of the divided module is significant. S value > 0.5 indicates that the clustering is reasonable, when S value > 0.7, the clustering is considered efficient and convincing. 22 Microsoft Excel 2019 was used for organizing the basic data. IBM SPSS 25.0 was used to conduct correlation analysis in the study.

Analysis of publication
In 1155 papers, there were 822 references included. Among the records removed were one book review, 29 editorial materials, 47 letters, 151 meeting abstracts, one news item, three notes, and 87 reviews. As shown in Figure 2, there has been an upward trend in the number of articles issued each year from a general perspective over the past 41 years. 1980-1994 could be seen as the first phase, and the overall trend was relatively stable, with little growth. The number of outputs per year was below 10, with an average number of articles published per year was 3.4. From 1995 to 2008 could be seen as the second phase, it showed fluctuating growth with an average annual publication of 12.286, and declined in the following years (1996, 2000, 2004, and 2007). The third phase was from 2009 to 2021, a period of rapid growth, with an average annual volume of 46.08. The number of publications per year was highly significantly and positively correlated with publication year (r = 0.851, p < 0.001). The overall publication trend is on the rise, indicating that researchers' interest in self-awareness related to LBP has increased and continues to advance.

Analysis of countries and institutions
There were 103 regions identified in citing countries through CiteSpace. The top five most citing countries were the United States of America (U.S.A., n = 181), England (n = 76), Australia (n = 71), Germany (n = 61), and the Netherlands (n = 38), followed with the Republic of China, Italy, South Korea, and Ireland. In CiteSpace, sigma is a combination of a structural attribute (mediated centrality) and a temporal attribute (burstiness), with higher sigma values indicating higher impact potential. 22 U.S.A. had the highest sigma score (290.49). Germany (7.7) and England (1.04) were the second and third; others were equal to 1. Meanwhile, in Figure 3, U.S.A. has the most connected lines with other countries which indicating the most intensive collaboration with other countries in LBP self-efficacy research. Taken together, in the field of LBP self-efficacy research, U.S.A. holds the largest volume, works closely with other countries, and this trend will continue due to its impact potential.
The visualization map was generated by the collaborating organization on Figure 4, with significant modularity and silhouette scores (Q = 0.9155, S = 0.9686). A total of 604 institutions were identified. Curtin University (n = 26), University of Sydney (n = 13), and University of Limerick (n = 9) were top three by citation counts. There were four organizations with the same citation counts 8 followed (the Haukeland Hospital, Oxford University, the University of Washington, and Harvard University). It shows a more dispersed distribution of study power in LBP self-efficacy. Nevertheless, the top five affiliations ranked by centrality were Curtin University, the University of Sydney, Harvard University, Maastricht University, and Erasmus University. In Figure 4, bursts only found in Curtin University in 2012 and the University of Sydney in 2015. In summary, Curtin University and the University of Sydney are in an important role in the development of this field. In the meantime, our cluster analysis based on the keywords revealed that the largest cluster was Cluster #0, with the label physiotherapy. The top three institutions by citation counts all belonged to the Cluster #0. This suggests that the intersection on physiotherapy and LBP self-management is a pivotal part of the discipline.

Analysis of subject categories
Every article belongs to one or more subject categories. After co-occurrence analysis, there were 93 WOS F I G U R E 2 Annual output and cumulative output about LBP of self-efficacy from 1980 to 2021. categories in 815 papers ( Figure 5). Neurosciences & Neurology had the highest number of articles (215 records, 26.380%), accounting for a quarter of the total. Following were clinical neurology (197 records, 24.172%), rehabilitation (155 records, 19.018%), orthopedics (154 records, 18.896%), and general and internal medicine (121 records, 14.770%). This network was divided into seven co-citation clusters. The largest cluster (#0) had 19 members, which was efficient and convincing (S > 0.7, S = 0.888). Among the top five disciplines in terms of number, the first, second, and fourth-ranked disciplines all belong to the cluster #0, and the average publication year is 1995.
In the development of subject categories, five subjects have citation bursts in 1980-2021 ( Figure 5), which belonged to Cluster #2 and Cluster #4. The top two and the fourth subject categories with the strongest citation bursts belonged to the Cluster #2, labeled as cognitivebehavioral therapy. This suggests that researchers have been linking LBP with cognitive-behavioral therapy since 1981, and the focus has been popular for more than 20 years. Medicine, general and internal, was the third burst subject belonging to the Cluster #4, qualitative study. It was the most recent burst happening from 2019 and may continue in the future. Nursing was the fifth burst subject, also belonging to Cluster #4, its bursts only lasted for 2 years, but still has high strength of burst. It demonstrated the importance placed on qualitative research as a research method in the discipline of nursing ( Figure 6). The top 10 co-cited journals are listed in Table 1, and the network map of co-citation journals is shown in Figure 7. The top five co-cited journals were: Spine (citation counts = 594), Pain (citation counts = 543), European Spine Journal (citation counts = 304), Lancet (citation counts = 296), and Clinical Journal of Pain (citation counts = 284). The highest cited publication F I G U R E 3 Mapping of cooperation networks between countries. Each node represents a country, and the lines linked between clusters indicate the cooperation relationship between countries (the thicker the line, the stronger the cooperation; the redder the color of the line, the earlier the year, and the more yellow shows closer to the present). Every circle inside represents publications in 1 year. Purple circles show the publication with high betweenness centrality, which is the key point to link two different research areas.

Analysis of journals
was "Reduction of Pain Catastrophizing Mediates the Outcome of Both Physical and Cognitive-Behavioral Treatment in Chronic Low Back Pain," for 394 times before 2022 in Journal of Pain. This research demonstrated that pain catastrophizing can be reduced by therapy aspects that do not specifically target in cognitive issues, and that pain catastrophizing was one of the important factors mediating functional activity to the patients with chronic LBP. 23 "Randomized clinical trial of lumbar instrumented fusion and cognitive intervention and exercises in patients with chronic low back pain and disc degeneration" was the most cited reference in Spine, and F I G U R E 4 Visualization map of collaborating organizations. Different color blocks represent the clusters with different labels through the keywords from publications. Each node shows one institution. The line between each node indicates the emergence of a cooperative relationship between institutions (colored lines represent more recent years; black and gray lines represent earlier years).

F I G U R E 5 Subject categories co-occurrence map of low back pain (LBP) self-efficacy.
the second among all for 380 times, which suggested the usage of multidisciplinary rehabilitation for chronic LBP, especially in cognitive intervention and exercise. 24 Among the publications and co-cited analysis, Spine and Pain were the core journals in the field of LBP self-efficacy.

Analysis of authors
The scientific mapping of published article's authors and cited authors were presented in Figure 8, showing the collaboration between authors and identifying the important authors in the field. The most prolific author was Peter O'Sullivan with 13 publications, followed by Kieran O'Sullivan and Anne Smith with 11 and six publications separately. In co-cited authors, Waddell G was the one who had the highest co-cited counts of 155 times, Deyo RA (147) was the second, and Roland M (130) was the third, followed by Chou R and Linton SJ (Table 2). On the centrality in co-cited authors, there were four authors with high centrality. Deyo RA had maximum centrality (0.24), followed by Waddell G (0.18), Turk DC (0.11), and Bandura A (0.10). The amount to which a node in a network was part of pathways that connected an arbitrary pair of nodes in the network was measured by centrality. 16 It indicated that these four authors were important in the development of research that derived LBP self-efficacy from other disciplines.
Peter O'Sullivan studying cognitive functional therapy, especially with nonspecific chronic LBP, was the most prolific author in LBP self-efficacy. A qualitative study using semi-structured interview to physiotherapists' perceptions after cognitive functional therapy training was his highest-cited paper. In this study, physiotherapists showed confidence in biopsychosocial dimensions of chronic LBP after the cognitive functional therapy training. 25 Cognitive functional therapy is a unique, comprehensive, patient-centered strategy that analyzes and regulates cognitive, psychological, and social aspects that are thought to be obstacles to healing in persistent LBP. 26,27 Previous studies have focused more on the effect of self-efficacy on the course of disease in patients with LBP, but this study extended the effect of perception to physiotherapists. Cognitive functional therapy is an expression of the progression of self-management from an evaluation tool to the application of treatment. This phenomenon was evidence of the development in multidisciplinary crossover. As the second most prolific author in this research area, Kieran O'Sullivan was also one of the co-authors of this paper.

Analysis of references
The top 10 papers with the maximum citation counts are shown in Table 3. Among these 10 papers, there are guidelines, medical devices, and systematic reviews. In terms of publication years, the earliest of them was published in 2006 (16 years ago). Taken together, it indicates that in this period, scholars valued the combination of evidence-based and practical, and relied on a higher quality of evidence. Meanwhile, the literature with high burst (red circles in Figure 9) were also these 10 articles. Timeline map (Figure 9) shows top 12 clusters. Using index terms, all clusters were labeled from the common characteristics of references. "Chronic low back pain," "posture," and "evidencebased management" were marked as the three largest clusters. The biggest cluster reflected current research interest in persistent LBP. Prior to this, studies concentrated on evidence-based therapy and postural control as themes connected to LBP self-management. As the F I G U R E 6 Top five subject categories with strongest citation bursts with LBP self-efficacy.
T A B L E 1 Top 10 journals with high co-citation counts.

Ranking
Cited journal

Analysis of terms and keywords
The keyword co-occurrence map was generated by CiteSpace with 640 nodes (Figure 10). The top keyword was low back pain, followed by disability, management, chronic low back pain, primary care, questionnaire, clinical trial, back pain, randomized controlled trial, and therapy. Therefore, the focus of current research in this area can be summarized in the following aspects: method, primary care, and back pain.
1. Method: clinical trials, especially randomized controlled trials are often used to determine the effectiveness of an intervention or to compare, which approach is more successful. Different types of disability functional rating questionnaires serve as important evaluation indicators in research. 24,26,28 F I G U R E 7 Minimum spanning tree of journal co-citation network. 2. Primary care: primary care is the first step before treatment begins. In LBP, cognitive-behavioral program enhances self-care. 29 Educational intervention program combined with exercise are also beneficial for primary care and self-management. 30,31 3. Back pain: it contains acute LBP, nonspecific LBP, upper back pain, and LBP. In the process of treatment, the value of self-efficacy and cognitive function therapy for persistent LBP is still being contested. 26,32 Pain relief through pharmacological intervention therapy is helpful in chronic LBP. 33,34 Figure 11 shows the top 16 keywords with highest burst strength through time. It indicates the term that had received more attention in each 1-year time slice, reflecting the emergent focus on the term in the field of study over a period.
In terms of the timing of the bursts about keywords, the scope of research has gradually refined over the past 20 years, from a focus on trial and primary care, through a brief period of psychological factors related to the theme of "fear avoidance," to these years' hotspot on specific populations among older adults T A B L E 2 Top 10 authors ranked by number of papers in first author, the first 10 co-cited authors ranked by co-citation number. and intervention in behavioral manifestations of cognitive. Meanwhile, older adults, cognitive-behavioral therapy, people, guideline, and reliability would be potentially forefronts in LBP self-efficacy research over the coming years. Although this study is the first to examine multiple aspects of bibliometric self-efficacy for LBP over the past 40 years, it still has limitations. First, for inclusion in the database, only WOS was used, despite it being recognized as one of the most important data sources in bibliometric analysis. Furthermore, while current research has been able to provide a comprehensive science mapping of the state in research on LBP self-efficacy, there are still functions to be discovered in CiteSpace software to have more in-depth integration. As CiteSpace is also a Java language-based software, there may be inevitable errors in the screening mechanisms and calculations due to the algorithm during the software analysis.

CONC LUSION
This is the first bibliometric analysis study about selfefficacy in LBP from 1980 to 2021. From this research, we can access the status and development of the field of LBP self-efficacy over the past 41 years. Publications on self-management and self-efficacy for LBP have been rising linearly and will continue to expand. U.S.A. held a significant dominance in this research area. It was the largest publication volume country, followed by England, Australia, and Germany. There was also close cooperation in universities and institutions between European countries and American. From the disciplinary point of view, it mainly involved neurosciences, rehabilitation, and orthopedics. General and internal medicine may continue to burst in the following years. Spine was the most recognized journal, had high co-citation counts, and provided a good communication platform for relevant research. It was noteworthy that there were numerous researchers involved, but even the authors with the highest number of publications did not publish a large quantity of articles. At the same time, lack of collaborative communication between authors might be because of the different specific research direction, for instance cognitive-behavioral therapy, knowledge interventions, and others. In terms of detailed research methods and content, clinical trials were the main way used for the most of studies. Cognitive-behavioral therapy in specific groups of people, especially in elders, might be the frontiers and trends of future research related to LBP self-efficacy.
This study provides an insight into the whole process of LBP self-efficacy over the past four decades. It gives researchers a basis for potential collaborations with other authors, other institutions, and guides the selection of publication platforms. Hot spots and trends within the field are predicted.

AU T HOR CON T R I BU T ION S
ZW planned the original idea, designed the study, and performed analysis. AM, MJ, and ZW developed the search strategies. ZW and KS drafting of the article. All authors revised the draft and approved the final version of the article.

CON F L IC T OF I N T E R E ST
The authors declare that they have no competing interests.

DATA AVA I L A BI L I T Y STAT E M E N T
The data that support the findings of this study are available from the corresponding author upon reasonable request.