Global research status and trends of somatic symptom disorder: A bibliometric study

Abstract

BACKGROUND

With the growing scholarly and clinical fascination with somatic symptom disorder (SSD), a bibliometric analysis is lacking.

AIM

To conduct a bibliometric analysis to investigate the current status and frontiers of SSD.

METHODS

The documents related to SSD are obtained from the web of science core collection database (WoSCC), and VOSviewer 1.6.16 from January 1, 2000 to December 31, 2023, and the WoSCC’s literature analysis wire were used to conduct the bibliometric analysis.

RESULTS

A total of 567 documents related to SSD were included, and 2325 authors across 947 institutions from 57 countries/regions have contributed to SSD research, published in 277 journals. The most productive author, institution, country and journal were Löwe B, University of Hamburg, Germany, and Journal of Psychosomatic Research respectively. The first high-cited document was published in the Journal of Psychosomatic Research in 2013 by Dimsdale JE and colleagues, which explored the rationale behind the SSD diagnosis introduction in diagnostic and statistical manual of mental disorders.

CONCLUSION

In conclusion, the main research hotspots and frontiers in the field of SSD are validity and reliability of the SSD criteria, functional impairment of SSD, and the treatment for SSD. More high-quality studies are needed to assess the diagnosis and treatment of SSD.

Key Words: Somatic symptom disorder; Validity and reliability; Functional impairment; Treatment; Bibliometric analysis

Core Tip: To the best of our knowledge, this is the first comprehensive bibliometric analysis of the somatic symptom disorder (SSD). The main research hotspots and frontiers in the field of SSD are validity and reliability of the SSD criteria, functional impairment of SSD, and the treatment for SSD. More high-quality studies are needed to assess the diagnosis and treatment of SSD.

INTRODUCTION

In 2013, somatic symptom disorder (SSD) was introduced as a new diagnosis in the diagnostic and statistical manual of mental disorders (DSM-5), which based on distressing somatic symptoms and the abnormal feelings, thoughts, and behaviors for them[1]. SSD presents a complex scenario where individuals experience profound and overwhelming distress or worry about physical symptoms that might not be linked to any identifiable medical condition[2]. Such distress significantly interferes with everyday life, impacting social, work, and other functional areas. Those with SSD often exhibit an increased awareness and concern for their bodily sensations, fearing that these symptoms could signal a severe, undiagnosed disease. Even after numerous medical assessments that typically don’t reveal a concrete physical cause, the concern for their health persists. SSD diagnosis highlights the critical connection between physical symptoms and psychological factors, with sufferers frequently experiencing intense health-related anxiety, leading them to seek medical attention often[3-6]. The introduction of SSD in DSM-5 represents a notable shift from previous versions, focusing less on the absence of a medical explanation for the symptoms and more on the individuals’ abnormal reactions, thoughts, and behaviors towards their symptoms. Treatment strategies aim at enhancing life quality, symptom management, and alleviating the distress and anxiety linked to the symptoms, often through a mix of psychotherapy, especially cognitive-behavioral therapy (CBT), and medication for managing anxiety and depression where applicable[7-9]. The objective is to foster healthier thought and reaction patterns to their symptoms, diminishing their impact on the individuals' lives.

With the growing scholarly and clinical fascination with SSD, a bibliometric analysis for the field of SSD is lacking. The bibliometric studies can compile research trends and spotlight new focal areas specifically for SSD research. Bibliometric analyses are crucial for mapping the development and broadening of literature, pinpointing key researchers, affiliations, and countries spearheading this research, and showcasing pivotal studies and innovative research directions[10,11]. They also help in uncovering yet-to-be-explored territories within the domain. Thus, we conducting a bibliometric analysis for offering the insights into the evolution of SSD research, highlighting its scientific achievements, and providing the reference for future research.

MATERIALS AND METHODS

Data collection and search methodology

The primary source for our bibliometric study was the web of science core collection (WoSCC), which is extensive and credible compilation of academic papers. The search was conducted using specific keywords: “Somatic symptom disorder”, “somatic symptom and related disorders”, and “somatic symptom disorders”. Given that the initial discourse on the SSD emerged in 2013, the timeframe for the search was set from January 1, 2013 to December 31, 2023. This search encompassed all publication types related to SSD without imposing any language restrictions.

Bibliometric analysis and data visualization techniques

After gathering the pertinent literature, we delved into various bibliometric indicators through the WoSCC online analysis platform. This investigation covered metrics such as the yearly distribution of publications, identification of the top 10 most prolific countries/regions, institutions, authors, and journals, as well as the top 20 most-cited papers on the subject of “somatic symptom disorder”. For a comprehensive analysis, the dataset-including information on publication years, authors, countries, regions, institutions, journals, keywords, and citations-was downloaded in TXT format, selecting the “Full Record and Cited References” option. We employed VOSviewer software (version 1.6.16) for the visualization of data sets, creating maps of co-authorship networks for keyword co-occurrence network, countries/regions, institutions, authors, journal and reference citation patterns. The visualizations generated were then prepared for presentation, enriching the findings from our bibliometric review.

RESULTS

Global publication insights

The bibliometric analysis unveiled a total of 567 documents related to “somatic symptom disorder” after a careful screening process, as depicted in Figure 1. Among these, there were 489 entries (86.2%) and 78 reviews (13.8%). The primary field of publication was psychiatry, claiming 311 documents and accounting for 66.6% of the total, with clinical psychology following at 83 publications (17.8%). The temporal trend observed from 2013 to 2023 in Figure 2 indicates a significant increase in scholarly output on SSD.

Figure 1  Flowchart of the inclusion and exclusion criteria.

Figure 2  The yearly quantity and literature type of publications on somatic symptom disorder.

Contributions by countries/regions, institutions, authors, and journals

A total of 2325 authors across 947 institutions from 57 countries/regions have contributed to SSD research, published across 277 journals. Löwe B stands out with a notable impact in the field, leading with 38 publications and 825 citations, demonstrating his significant influence on SSD research. Witthöft M and Toussaint A also being notable for their substantial contributions of 23 and 18 publications, respectively. University of Hamburg is at the forefront among institutions with 60 publications, closely followed by the Johannes Gutenberg University of Mainz, and Technical University of Munich with 37 publications, and the University of Bologna with 33 publications. The Germany leads in terms of publications with 185 papers, which have attracted a noteworthy 2433 citations and achieved an H-index of 26, showcasing the significant volume and impact of its research contributions. United States and Netherlands also stand out with 102 and 50 publications, respectively. The Journal of Psychosomatic Research, Frontiers in Psychiatry and Psychosomatic Medicine are the most productive in the field, with 57, 29 and 25 publications, respectively. The most influential authors, institutions, countries/regions and journals within the SSD research community are detailed in Table 1 and Table 2, while network visualization maps illustrating relationships among institutions, countries/regions, authors, and journals are provided in Figure 3 and Figure 4A.

Figure 3 The visualization knowledge maps of co-authorship. A: The co-authorship map of authors that indicates the authors who cooperate in the field of somatic symptom disorder; B: The co-authorship map of organizations; C: The co-authorship map of countries.

Figure 4 The visualization knowledge. A: Maps of journals; B: References; C: Keyword co-occurrence analysis.

Table 1 Ranking of the most productive 10 authors, institutions and countries.

	Ranking	Items	Counts	% of 568	Citations	H-index
Authors	1	Löwe B	38	6.69	825	15
	2	Witthöft M	23	4.049	290	8
	3	Toussaint A	18	3.169	502	11
	4	Fritzsche K	16	2.817	205	7
	5	Huang WL	16	2.817	176	8
	6	Henningsen P	15	2.641	590	9
	7	Leonhart R	15	2.641	203	7
	8	Van Der Feltz-cornelis CM	15	2.641	163	9
	9	Rief W	14	2.465	492	8
	10	Sattel H	13	2.289	145	7
Affiliations	1	University of Hamburg	60	10.563	941	16
	2	Johannes Gutenberg University of Mainz	37	6.514	487	11
	3	Technical University of Munich	33	5.81	900	14
	4	University of Freiburg	26	4.577	294	10
	5	Harvard University	23	4.049	402	8
	6	Ruprecht Karls University Heidelberg	23	4.049	279	9
	7	Philipps University Marburg	21	3.697	576	12
	8	University of London	20	3.521	368	12
	9	National Taiwan University	16	2.817	176	8
	10	University of Munich	16	2.817	195	7
Countries	1	Germany	185	32.57	2433	26
	2	United States	102	17.958	1456	23
	3	Netherlands	50	8.803	657	14
	4	England	49	8.627	935	16
	5	Italy	46	8.099	609	14
	6	China	43	7.57	523	10
	7	Canada	34	5.986	557	13
	8	Japan	26	4.577	125	6
	9	Australia	23	4.049	508	11
	10	Switzerland	21	3.697	318	10

Table 2 Ranking of the most productive 10 journals based on publications.

Ranking	Publication titles	Record count	Citations
1	Journal of Psychosomatic Research	57	865
2	Frontiers In Psychiatry	29	193
3	Psychosomatic Medicine	25	450
4	Bmc Psychiatry	18	107
5	General Hospital Psychiatry	11	174
6	Frontiers In Psychology	8	55
7	Psychological Medicine	6	158
8	Psychosomatics	6	76
9	Psychotherapeut	6	11
10	Journal of Affective Disorders	5	153

Key publications

Figure 4B showcases a network visualization map detailing citation of publications. The characteristics of the top 20 most-cited articles are summarized in Table 3[12-31]. The leading article, appearing in the Journal of Psychosomatic Research in 2013 by Dimsdale et al[2], explores the rationale behind the SSD diagnosis introduction in DSM-5. This paper marks a pivotal shift in focus from symptoms lacking medical explanations to recognizing SSD based on persistent physical symptoms that profoundly affect an individual’s thoughts, emotions, and behaviors. It assesses the reliability, validity, and prevalence of SSD, pointing out directions for future research, educational endeavors, and clinical practices. The second noteworthy article, published in Psychosomatic Medicine in 2016 by Toussaint A and team, introduces the SSD-B criteria scale (SSD-12), a newly formulated self-report questionnaire for evaluating DSM-5’s psychological aspects. The study validates the scale's reliability and applicability for further exploration in both research and clinical settings. The third influential piece, authored by Burton C and published in BMC Medicine in 2020, critiques the DSM-5’s approach to SSD in the context of chronic pain. It argues that the diagnosis overly psychologizes individuals with chronic pain, leading to misdiagnosis and unnecessary stigma, suggesting that adjustment disorder offers a more precise and acceptable diagnostic alternative for those overly concerned with their pain. The fourth significant publication, featured in the Journal of the Canadian Journal of Psychiatry in 2015 by Katz J and co-authors, recommends adopting ‘functional somatic disorders’ as a collective term for conditions characterized by enduring and problematic physical symptoms. The fifth prominent publication by Tomenson B, appearing in the British Journal of Psychiatry in 2013, identifies the total somatic symptom score as a predictive tool for health status and healthcare utilization, beyond the impacts of anxiety, depression, and general medical conditions.

Table 3 Ranking of the top 20 highest cited references.

Ranking	Publications	Journal	Year	Citations	First author
1	Somatic symptom disorder: An important change in DSM	Journal of Psychosomatic Research	2013	154	Dimsdale JE
2	Development and validation of the somatic symptom disorder-B criteria scale	Psychosomatic Medicine	2016	136	Toussaint A
3	Functional somatic disorders: Discussion paper for a new common classification for research and clinical use	BMC Medicine	2020	103	Burton C
4	Chronic pain, psychopathology, and DSM-5 somatic symptom disorder	Canadian Journal of Psychiatry	2015	127	Katz J
5	Total somatic symptom score as a predictor of health outcome in somatic symptom disorders	British Journal of Psychiatry	2013	94	Tomenson B
6	Irritable bowel syndrome: Relations with functional, mental, and somatoform disorders	World Journal of Gastroenterology	2014	102	Hausteiner-Wiehle C
7	Core outcome domains for clinical trials on somatic symptom disorder, bodily distress disorder, and functional somatic syndromes: European network on somatic symptom disorders recommendations	Psychosomatic Medicine	2017	77	Rief W
8	Detecting DSM-5 somatic symptom disorder: criterion validity of the patient health questionnaire-15 and the somatic symptom scale-8 in combination with the somatic symptom disorder-B criteria scale	Psychological Medicine	2020	80	Toussaint A
9	Management of somatic symptom disorder	Dialogues In Clinical Neuroscience	2018	78	Henningsen P
10	Validation of patient health questionnaire for major depression in Chinese outpatients with multiple somatic symptoms: A multicenter cross-sectional study	Journal of Affective Disorders	2015	83	Xiong NN
11	Somatic symptom disorder	American Family Physician	2016	76	Kurlansik SL
12	Health anxiety and hypochondriasis in the light of DSM-5	Anxiety Stress and Coping	2016	75	Bailer J
13	DSM-5 illness anxiety disorder and somatic symptom disorder: Comorbidity, correlates, and overlap with DSM-IV hypochondriasis	Journal of Psychosomatic Research	2017	70	Newby JM
14	Pediatric somatic symptom disorders	Current Psychiatry Reports	2017	66	Malas N
15	Exposure-based cognitive-behavioral therapy via the Internet and as bibliotherapy for somatic symptom disorder and illness anxiety disorder: Randomized controlled trial	British Journal of Psychiatry	2016	67	Hedman E
16	The efficacy of cognitive behavioral therapy in somatoform disorders and medically unexplained physical symptoms: A meta-analysis of randomized controlled trials	Journal of Affective Disorders	2019	61	Jing L
17	Patients with unexplained physical symptoms have poorer quality of life and higher costs than other patient groups: A cross-sectional study on burden	BMC Health Services Research	2013	60	Zonneveld LNL
18	Health anxiety and illness-related fears across diverse chronic illnesses: A systematic review on conceptualization, measurement, prevalence, course, and correlates	Plos One	2020	66	Lebel S
19	Identifying the key characteristics of clinical fear of cancer recurrence: An international Delphi study	Psycho-Oncology	2020	60	Mutsaers B
20	Structural alterations in functional neurological disorder and related conditions: a software and hardware problem?	Neuroimage-Clinical	2019	58	Bègue I

Analysis of keywords

In the bibliometric network visualization, a complex interrelation of topics centered around SSD were observed, which was displayed in Figure 4C. The map is segmented into distinct color-coded clusters, each representing a thematic concentration within the research landscape. The green cluster, which anchors the network, is closely associated with ‘somatic symptom disorder’ and branches out to related terms such as ‘somatoform disorders’, ‘cognitive-behavioral therapy’, and ‘functional somatic syndromes’. This implies a strong research focus on the clinical and therapeutic aspects of somatic symptomatology and its treatment. Red clusters are tightly knit around ‘depression’, intersecting with ‘anxiety’, ‘chronic pain’, and ‘somatization’, highlighting the psychological dimensions of somatic symptoms and their comorbidity with mental health disorders. The blue cluster orbits around ‘health anxiety’ and ‘hypochondriasis’, suggesting an investigative thread into the anxiety disorders spectrum as it pertains to somatic symptomatology. Finally, the yellow cluster, though smaller and less dense, includes terms like ‘bodily distress’, which may denote a more specialized subset of research within the somatic symptom domain, possibly dealing with physical distress and its psychosocial components.

DISCUSSION

General information

To the best of our knowledge, this is the first comprehensive bibliometric analysis of the SSD. In total, 567 publications were included and analyzed. From 2013 to 2023, the number of publications related to SSD increased annually, suggesting an escalating interest and expanding research volume over the decade. This surge might be attributed to increased recognition of the disorder, improvements in diagnosis, or a greater understanding of its effects on patient life quality. The rising trend signifies not only an increase in publication frequency but possibly also a boost in citation numbers, reflecting the growing influence and recognition of SSD research. Moreover, this trend may indicate a widening scope of interdisciplinary research contributions towards a comprehensive understanding of SSD. The most productive author, institution, country and journal were Löwe with 38 publications, University of Hamburg with 60 publications, Germany with 185 publications, and Journal of Psychosomatic Research with 57 publications, respectively. A landmark study by Dimsdale et al[2], published in the Psychosomatic Research in 2013, discusses the rationale behind the SSD diagnosis introduction in DSM-5. The keyword analysis underscores the multidisciplinary nature of SSD research, bridging mental health, physical health, therapy approaches, and the societal and psychological implications of the disorder.

Hotspots and frontiers

Based on publications of SSD, important keywords related to SSD, and highly-cited publications, the research hotspots in the field of SSD were summarized as follows.

Validity and reliability of the SSD criteria: The criteria for SSD as detailed in the DSM-5 have been crucial for the progress in diagnosing and understanding SSD[32,33]. These criteria’s validity concerns how accurately they identify actual SSD cases, focusing on the presence of somatic symptoms that cause significant distress or impact daily life, rather than on the lack of a medical explanation for these symptoms. Research has largely affirmed the criteria’s validity, showing they effectively identify individuals significantly affected by their somatic symptoms. However, the criteria’s validity faces challenges due to the subjective assessment of what constitutes “excessive” thoughts, feelings, or actions related to these symptoms, which may differ greatly across individuals and cultures. Reliability pertains to how consistently SSD can be diagnosed across various clinicians and over time[34-36]. Studies have shown a reasonable level of agreement among healthcare professionals using the DSM-5 criteria to diagnose SSD, supporting the criteria’s reliability[37,38]. Yet, difficulties in reliably assessing the degree of thoughts, feelings, or behaviors and the subjective nature of determining distress or functional impairment challenge this reliability. Additionally, the criteria’s broad and somewhat ambiguous nature can result in differences in interpretation among clinicians. While introducing SSD in DSM-5 marked an advancement in acknowledging the intricate relationship between psychological and physical symptoms, ongoing research is essential to refine these criteria and improve their validity and reliability.

Functional impairment of SSD: DSM-5 defines SSD by emphasizing the occurrence of distressing physical symptoms along with significant impairment in functioning or overly intense and disproportionate thoughts, feelings, or actions concerning these symptoms[39-41]. The diagnosis of SSD is pivotal, highlighting the extent to which these symptoms and the person’s reaction to them can disrupt normal daily activities. Such disruptions can span across work, social engagements, and personal relationships, with individuals potentially facing difficulties in keeping a job, isolating themselves due to anxiety or shame related to their symptoms, or battling with routine tasks and self-care[42-46]. An obsessive preoccupation with health issues may result in repeated medical consultations, superfluous testing, and a relentless quest for assurance about one’s health status, aggravating the person’s distress and functional decline. Additionally, the psychological and emotional dimensions of SSD, including continuous concern over the severity of symptoms, a sense of powerlessness, and an acute focus on physical sensations, can hinder normal functioning. This creates a detrimental loop of deteriorating symptoms and further decline in day-to-day functioning. The profound effect on functional capabilities highlights the necessity to perceive and manage SSD not merely as a sum of physical symptoms but as an intricate condition impacting the person’s life quality and their participation in daily activities.

Treatment for SSD: Treating SSD requires a comprehensive and interdisciplinary strategy, encompassing physiotherapy, medication, psychological therapy, and a unified treatment program to tackle the disorder’s both physical and mental facets[47,48]. Psychological therapy is pivotal for the cognitive and emotional aspects of SSD, with CBT aiding in the identification and restructuring of negative thought patterns related to symptoms, and in developing strategies to handle distress[7,9,49-51]. Additionally, mindfulness-based practices can improve patients’ perception of bodily sensations in a non-critical manner, aiding in the reduction of symptom-driven anxiety and depression. In terms of medication, managing SSD focuses on symptom relief. Antidepressants like selective serotonin reuptake inhibitors and tricyclic antidepressants are often used for their benefits in easing depression and anxiety symptoms, which frequently accompany SSD[52-54]. These drugs may also lessen some physical symptoms, particularly those associated with mood disorders. Antidepressants or anticonvulsants in low doses may be employed for pain management, and benzodiazepines might be considered for short-term anxiety relief, with careful use to avoid dependency. It’s crucial that pharmacological treatment be part of a broader therapy plan, incorporating psychological and behavioral techniques, since medications alone may not fully resolve SSD’s multifaceted symptomatology. Physiotherapy can enhance patients’ physical capabilities and movement, employing specific exercises to boost strength, flexibility, endurance, and employing pain relief techniques such as thermotherapy, massage, and electrotherapy to ease discomfort[55]. These interventions not only aim to diminish the intensity of physical symptoms but also enhance patients’ ability to perform everyday tasks. The treatment for SSD should be personalized, considering the patient’s specific symptoms, medical history, and therapy response. Integrated therapy entails a collaborative effort among various healthcare professionals to formulate a tailored treatment plan, often involving joint discussions among physiotherapists, psychologists, general practitioners, and specialists to ensure care is cohesive and goals are comprehensive, aiming at enhancing the patient's life quality and functionality. Through such an integrated treatment approach, significant progress can be made in both alleviating physical symptoms and enhancing mental health in individuals with SSD.

Further research on SSD should aim to deepen the understanding of the biological, psychological, and social factors contributing to the development and persistence of the disorder. Longitudinal studies could provide insights into the progression of symptoms and identify early predictors of chronic SSD. Moreover, investigating the effectiveness of various therapeutic interventions, such as CBT, pharmacotherapy, and integrated care models, in diverse populations would be beneficial. Research should also explore the impact of SSD on individuals’ quality of life and functioning, including how comorbidities, such as anxiety and depression, may influence treatment outcomes. Additionally, incorporating neuroimaging and genetic studies could help uncover potential biomarkers and neurobiological underpinnings, ultimately paving the way for more personalized and effective treatment strategies.

There are several limitations in our study. Firstly, the publications related to SSD were exclusively retrieved from the WoSCC database, which may limit the generalizability of the findings. Secondly, the field of SSD is considered niche and emerging, so the overall volume of documents related to SSD is relatively small, potentially limiting the comprehensiveness of the investigation. In addition, although the DSM-5 has a detailed and clear descriptive diagnosis of SSD, the evaluation of SSD-related symptoms and severity still mainly relies on related psychological questionnaires or scales in clinical practice.

CONCLUSION

In conclusion, the main research hotspots and frontiers in the field of SSD are validity and reliability of the SSD criteria, functional impairment of SSD, and the treatment for SSD. More high-quality studies are needed to assess the diagnosis and treatment of SSD.