|Year : 2013 | Volume
| Issue : 3 | Page : 176-183
Status of current research evidence on diabetic neuropathy from a 40-year quantitative trend analysis of published articles in PubMed: A descriptive study
Senthil P Kumar1, Adhikari Prabha2, PS Jeganathan3, ZK Misri4, Vaishali Sisodia5
1 Department of Physiotherapy, Maharishi Markandeshwar Institute of Physiotherapy and Rehabilitation, Maharishi Markandeshwar University, Mullana, Ambala, Haryana, India
2 Department of Medicine, Kasturba Medical College, (Manipal University), Mangalore, Karnataka, India
3 Department of Physiology, Kasturba Medical College, (Manipal University), Mangalore, Karnataka, India
4 Department of Neurology, Kasturba Medical College, (Manipal University), Mangalore, Karnataka, India
5 Department of Physiotherapy, Srinivas College of Physiotherapy and Research Centre, Pandeshwar, India
|Date of Web Publication||14-Feb-2014|
Senthil P Kumar
Department of Physiotherapy, Maharishi Markandeshwar Institute of Physiotherapy and Rehabilitation, Maharishi Markandeshwar University, Mullana, Haryana
Source of Support: None, Conflict of Interest: None
Background: Neuropathy is the most common complication of diabetes mellitus and diabetes is the highly prevalent non-communicable life-style disorder until the date. Diabetic neuropathy (DN) presents a clinical challenge, with chronic disabling pain, neurological dysfunction, and impaired quality of life. Objective: The objective of this study was to explore the evidence base for DN descriptively and report the current state of published articles indexed in PubMed. Materials and Methods: Descriptive exploratory study through a literature search was carried out to identify 9 time-points in the timeline from 1970-2010, with 5-year intervals in order to identify the scientific trend for the evidence-base in DN. The number of obtained citations were classified and analyzed under the names of search filters of PubMed namely - text availability, publication date, species, article type, language, gender, journal categories, age, and subject areas. The numbers for categories and subcategories of search filters were considered for comparison and analysis. Descriptive analysis using the frequencies on Microsoft Excel 2010 worksheet was carried out. Results: Although overall number of articles was less, there was an exponential increase in number of articles in DN over the 40 years. After comparison for various categories and sub-categories, there was a greater prevalence of "abstract available" articles, human studies, reviews, English language, MEDLINE journals, Middle-age population and cancer, with nearly equal gender representation. Conclusion: This study explored the existing research articles indexed in PubMed utilizing a quantitative approach reflected the status of current practice-based evidence. Future analyzes on DN should address diabetes-specific and age-specific influences on evidence.
Keywords: Diabetic neuropathy evidence, diabetic neuropathy research, evidence-based diabetes care, health informatics
|How to cite this article:|
Kumar SP, Prabha A, Jeganathan P S, Misri Z K, Sisodia V. Status of current research evidence on diabetic neuropathy from a 40-year quantitative trend analysis of published articles in PubMed: A descriptive study. Saudi J Health Sci 2013;2:176-83
|How to cite this URL:|
Kumar SP, Prabha A, Jeganathan P S, Misri Z K, Sisodia V. Status of current research evidence on diabetic neuropathy from a 40-year quantitative trend analysis of published articles in PubMed: A descriptive study. Saudi J Health Sci [serial online] 2013 [cited 2023 Mar 22];2:176-83. Available from: https://www.saudijhealthsci.org/text.asp?2013/2/3/176/127056
| Introduction|| |
Neuropathy is one of the most common complication in people with diabetes mellitus  and diabetes is the leading non-communicable life-style-associated disorder in both the developed and developing countries around the world.  Neuropathic pain (NP) in people with diabetic neuropathy (DN) is characterized by the bilateral tingling and numbness in the "glove and stocking" distribution of peripheral nerves, more commonly in the lower limb, with sensory and/or motor deficits, sleep disturbances, psychosocial interference, and reduced quality of life. 
Whilst DN can affect somatic and/or autonomic nervous system,  and small-fiber and/or large-fiber neurons,  in both or either the central or peripheral nervous system,  diabetic peripheral neuropathy (DPN) is the most common clinical presentation of DN.  The painful state in DPN is clinically denoted as diabetic peripheral neuropathic pain (DPNP)  and the disorder is terminologically recognized as painful DPN. 
The evaluation of patients with DN include a comprehensive approach that includes assessment of clinical examination findings  of NP, neurodynamics, quality of life  using the standardized validated clinical assessment scales  and neurodynamic examination.  The management of DN consisted of medical/pharmacological,  surgical,  physiotherapeutic,  neurodynamic, , and alternative interventions. ,
Evidence-based practice (EBP) or evidence-informed practice (EIP) denotes the thoughtful self-reflective reasoning-based application of information from recent scientific evidence toward effective individualized patient evaluation and management along a comprehensive multidisciplinary biopsychosocial model. ,, Evidence base for EBP and EIP is substantially provided by the most widely accessed and commonly searched database like PubMed,  which is a service provided by national library of medicine with more than 22 million records available on biomedical literature.
There is a need to evaluate the evidence provided by evidence-oriented databases in order to explore the status of practice-based research  on DN. The objective of this study was to explore the evidence base for DN articles in PubMed through its advanced search methods and search filters, and descriptively report the current state of evidence.
| Materials and Methods|| |
Descriptive exploratory study
Two reviewers performed an independent blinded search of PubMed using the specific search strategy and they independently extracted and synthesized the data from the selected studies using a structured check-list. At all stages of the review process (initial search, scrutiny of citations by title, scrutiny of citations by abstracts and relevance to study objective), all disagreements were solved by mutual consensus between both the authors before proceeding to the subsequent stages of the review. This search methodology was a replication of a previous study by Kumar and Sisodia. 
A combination of using advanced search methods and search filters in PubMed was used as per descriptions in previous studies. ,,, A thorough literature search using keywords "(diabetes [Title/Abstract] or diabetic [Title/Abstract]) and (neuropathy [Title/Abstract] or neuropathic [Title/Abstract])" was carried out to identify 9 time-points in the timeline from 1970-2010 as a 40-year period, with 5-year intervals in order to identify the scientific trend. The search was performed in the month of November 2012, and retrieved numbers of citations were then used as data for extraction and synthesis.
Data extraction and synthesis
The number of obtained citations were classified and analyzed under the names of search filters of PubMed namely - text availability, publication date, species, article type, language, gender, subject area, journal category, and age. The numbers for categories and subcategories of search filters were considered for comparison and analysis.
All data were entered in Microsoft Excel 2010 worksheet and computed descriptively using their respective frequencies-numbers and percentiles. All comparisons were performed visually in order to obtain an overall appearance and trend.
Results: Main findings
Total number of DN-related articles in the specific time period (1970-2010) was 11,378.
There were a greater number of "abstract available" articles followed by "full text available" articles and "free full text available" articles [Figure 1]. The trend of growth in number of articles followed a similar pattern [Figure 2].
|Figure 1: Relative prevalence of sub-categories for text availability among diabetic neuropathy-related articles|
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|Figure 2: Comparison of 40-year trend between the two subcategories of text availability among diabetic neuropathy-related articles|
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Number of articles
The number of articles increased over the years, with an exponential increase observed from 1995 onwards [Figure 3].
|Figure 3: Trend for number of articles on diabetic neuropathy indexed in PubMed per year based upon publication year|
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The number of articles and the trend of increase were more in human studies than on other animals' studies [Figure 4] and [Figure 5].
|Figure 4: Relative prevalence of sub-categories for species among diabetic neuropathy-related articles|
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|Figure 5: Comparison of 40-year trend between the two subcategories of species among diabetic neuropathy-related articles|
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Types of articles
The number of articles and the trend of increase were the greatest in the following order: Review articles, systematic reviews and comparative studies [Figure 6].
|Figure 6: Relative prevalence of sub-categories for article types among diabetic neuropathy-related articles|
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The number of articles and the trend of increase was more for studies on English language than on other languages [Figure 7] and [Figure 8].
|Figure 7: Relative prevalence of sub-categories for language among diabetic neuropathy-related articles|
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|Figure 8: Comparison of 40-year trend for English language diabetic neuropathy-related articles|
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Number of articles focusing on male gender was marginally higher than that on female gender [Figure 9]. The number of articles on either gender increased steadily over the years, with no much difference between each other [Figure 10].
|Figure 9: Relative prevalence of sub-categories for gender among diabetic neuropathy-related articles|
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|Figure 10: Comparison of 40-year trend for diabetic neuropathy-related articles based upon gender|
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The greatest number of articles was present under categories of cancer, veterinary sciences, and toxicology [Figure 11].
|Figure 11: Relative prevalence of sub-categories for subject areas among diabetic neuropathy-related articles|
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The greatest number of articles and the greatest increase in number of articles over the years were present under MEDLINE, core clinical journals and dental and nursing journals [Figure 12] and [Figure 13].
|Figure 12: Relative prevalence of sub-categories for journal categories among diabetic neuropathy-related articles|
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|Figure 13: 40-year trend for number of diabetic neuropathy-related articles published in MEDLINE journals and core clinical journals|
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| Age of Study Population|| |
The greatest number of articles and the greatest increase in number of articles over the years were present for Middle age, adult, and aged [Figure 14] and [Figure 15].
|Figure 14: Relative prevalence of sub-categories for age among diabetic neuropathy-related articles|
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|Figure 15: Comparison of 40-year trend for diabetic neuropathy-related articles based upon age|
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| Discussion|| |
This study aimed at exploring the evidence base of PubMed among DN-related articles in the nature and characteristics of published articles, which are indexed from 1970-2010. The total number of articles on DN was 11,378, which were far lesser in proportion (0.0006%) to total number of 17,445,795 articles in PubMed reported previously by Kumar and Sisodia  The search strategy used in both studies was a search filter-based quantitative analysis performed using a descriptive approach. The difference between the two papers is that the former is on PubMed in general, and this study was on DN in particular. The first study provided a baseline data, upon which we could interpret the available number of studies on DN. Although the overall number of articles on DN was relatively low, there is a rapid increase in recent years with greater number of articles demonstrating practice-based research. These trend findings were similar to the overall trend for evidence on diabetes in PubMed reported earlier. 
The study findings are of immense importance to all biomedical scientists working on diabetes and neuropathy, and clinicians and researchers in search of evidence would be prepared to expect information related to DN from PubMed. However, this does not detail on the quality of evidence per se, and future analyses should explore levels of evidence, and other related attributes, which contribute to critical appraisal of obtained evidence. 
Searching PubMed was one of the acceptable limitations of this study albeit the inclusion of some journals, which are not indexed in MEDLINE, to have their abstracts indexed through Pubmed central's open-access archiving policy.  This study evaluated the existence of evidence and not its impact, which could be analyzed by high-impact journals and their contribution to evidence of DN. Scientific reliability is the reproducibility of search strategy, and methodology, which although is not validated for the present study, the one used was a well-known method as described in the database.
Application of evidence into practice relied on a continuum of knowledge generation to knowledge translation,  and based upon an inference that not all evidence is practice-related or practice-based. Strategies for effective implementation of evidence into practice depend upon the knowledge, attitudes, beliefs, and perceived barriers to EBP/EIP and many individual and institutional stakeholders and policy makers play a major role in it. 
Other databases such as Scopus,  Web of science,  Google scholar,  EMBASE,  CINAHL,  and Cochrane library  also provide research evidence on diabetes and neuropathy, and hence future studies could be performed on other such databases. With growing access to evidence-based statements and consumer summaries,  the increased number of "abstract available" articles for diabetes in PubMed enables quicker knowledge transfer compared to links to "full text available" articles, which provide information upon payment. 
Various indexation-related factors such as publishing policies of journals, editorial skills, and indexing categorization by technical staff influence the actual existence of evidence and also the amount of evidence retrieved through search.  Frequent and periodical analysis of evidence in PubMed is necessary after implementing a change as a process of outcome evaluation. 
Interestingly, the study findings reflected current evidence for practice, in that the greatest number of articles available reflected the actual scientific information on diabetes and neuropathy. For example, number of "DN" articles under middle-age were more so as the prevalence in middle-age. 
Relatively equal representation of gender in existed evidence with a shift toward male gender reflected increased prevalence of DN among men,  and more human studies demonstrated a "bench-to-bedside" effect with a translation from experimental (animal) models to clinical presentation of DPNP. 
MEDLINE journals had the greatest number of "diabetes" articles since there are many MEDLINE-indexed diabetes journals, which are published as monthly issues.  This study evaluated evidence for DN and future studies on analysis of diabetes journals would be of immense value to delineate the role of diabetes journals.
The leading subject category for DN articles was cancer, which may be due to the comorbid occurrence of diabetes with cancer in relation to their etiological association to neuropathy through vitamin-D.  Both disorders are known for their genetic and life-style-associated incidence in recent years, and both have a global magnitude of public health burden.  Similarly, more studies under veterinary sciences and toxicology denote increased number of experimental studies and drug-related adverse event studies respectively.
The study however had few limitations in being descriptive and not analytical; lack of content analysis, lack of quality analysis,  and possibility of influence of indexation errors on retrieved results  and subsequent study findings, which were not categorized into practice-based, practice-related or practice articles. Future analyzes of evidence should focus on diabetes, neurology, and anesthesiology journals utilizing "advanced search" features of PubMed  to determine their contribution of diabetes evidence base for DN.
The total number of articles on DN was 11,378, which were far lesser in proportion (0.0006%) to total number of 17,445,795 articles in PubMed reported previously by Kumar and Sisodia  This study found that the evidence-analysis utilizing a quantitative approach reflected the status of current practice-based evidence in DN. Future analyzes on DN should address journal-specific, population-specific, and age-specific influences on quantity and quality of research evidence.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13], [Figure 14], [Figure 15]