bims-evares Biomed News
on Evaluation of research
Issue of 2019‒03‒03
fifteen papers selected by
Thomas Krichel
Open Library Society


  1. PLoS One. 2019 ;14(2): e0211460
      The UK is one of the largest funders of health research in the world, but little is known about how health funding is spent. Our study explores whether major UK public and charitable health research funders support the research of UK-based scientists producing the most highly-cited research. To address this question, we searched for UK-based authors of peer-reviewed papers that were published between January 2006 and February 2018 and received over 1000 citations in Scopus. We explored whether these authors have held a grant from the National Institute for Health Research (NIHR), the Medical Research Council (MRC) and the Wellcome Trust and compared the results with UK-based researchers who serve currently on the boards of these bodies. From the 1,370 papers relevant to medical, biomedical, life and health sciences with more than 1000 citations in the period examined, we identified 223 individuals from a UK institution at the time of publication who were either first/last or single authors. Of those, 164 are still in UK academic institutions, while 59 are not currently in UK academia (have left the country, are retired, or work in other sectors). Of the 164 individuals, only 59 (36%; 95% CI: 29-43%) currently hold an active grant from one of the three funders. Only 79 (48%; 95% CI: 41-56%) have held an active grant from any of the three funders between 2006-2017. Conversely, 457 of the 664 board members of MRC, Wellcome Trust, and NIHR (69%; 95% CI: 65-72%) have held an active grant in the same period by any of these funders. Only 7 out of 655 board members (1.1%) were first, last or single authors of an extremely highly-cited paper. There are many reasons why the majority of the most influential UK authors do not hold a grant from the country's major public and charitable funding bodies. Nevertheless, the results are worrisome and subscribe to similar patterns shown in the US. We discuss possible implications and suggest ways forward.
    DOI:  https://doi.org/10.1371/journal.pone.0211460
  2. Int J Radiat Biol. 2019 Feb 26. 1-48
      The International Journal of Radiation Biology (IJRB) celebrates its sixtieth birthday this year. Ahead of this very special issue, we wanted to produce strong representations of the journal's publication history in order to celebrate the current status of the journal and to look forward to its future. This was accomplished using "reference maps". Reference data was used from 1959 onward from the highest-cited paper in IJRB, for each respective year, to create a figure displaying when those articles were cited in IJRB since their publication. This was done to show the relative impact of historical IJRB papers to future research. Common themes of research were also examined by decade. Additionally, to show the historical impact of the journal outside of its immediate area of research and its practical applications, information on IJRB articles cited by the International Commission on Radiological Protection (ICRP) was collected. It was in 1959 when IJRB published the first issue, and when the International Commission on Radiological Protection (ICRP) also issued Publication 1. Among all Publications (1-139), 43 publications have thus far cited 320 IJRB papers and each of which have been cited 1-7 times. Most notably, Publications 90, 99, 118 and 131 cited more than 40 IJRB papers. Further research was done into references for IJRB's contemporary journal: Radiation Research. The most highly-cited IJRB articles for each year together since its inception were cited 16,760 times since they were published and cited 1385 times in Radiation Research. Together, these three datasets and their representations show the diversity of historical IJRB publications, the impact of historical IJRB articles in both future research in the journal and outside of it, and articles which new prospective authors contributing to IJRB might find useful in their own research.
    Keywords:  International Commission on Radiological Protection (ICRP); International Journal of Radiation Biology (IJRB); Publication history; Reference map; citations
    DOI:  https://doi.org/10.1080/09553002.2019.1587195
  3. J Transl Med. 2019 Feb 28. 17(1): 67
      BACKGROUND: Gastrointestinal microbiome has drawn an increasing amount of attention over the past decades. There is emerging evidence that the gut flora plays a major role in the pathogenesis of certain diseases. We aimed to analyze the evolution of gastrointestinal microbiome research and evaluate publications qualitatively and quantitatively.METHODS: We obtained a record of 2891 manuscripts published between 1998 and 2018 from the Web of Science Core Collection (WoSCC) of Thomson Reuters; this record was obtained on June 23, 2018. The WoSCC is the most frequently used source of scientific information. We used the term "Gastrointestinal Microbiomes" and all of its hyponyms to retrieve the record, and restricted the subjects to gastroenterology and hepatology. We then derived a clustered network from 70,169 references that were cited by the 2891 manuscripts, and identified 676 top co-cited articles. Next, we used the bibliometric method, CiteSpace V, and VOSviewer 1.6.8 to identify top authors, journals, institutions, countries, keywords, co-cited articles, and trends.
    RESULTS: We identified that the number of publications on gastrointestinal microbiome is increasing over time. 112 journals published articles on gastrointestinal microbiome. The United States of America was the leading country for publications, and the leading institution was the University of North Carolina. Co-cited reference analysis revealed the top landmark articles in the field. Gut microbiota, inflammatory bowel disease (IBD), probiotics, irritable bowel disease, and obesity are some of the high frequency keywords in co-occurrence cluster analysis and co-cited reference cluster analysis; indicating gut microbiota and related digestive diseases remain the hotspots in gut microbiome research. Burst detection analysis of top keywords showed that bile acid, obesity, and Akkermansia muciniphila were the new research foci.
    CONCLUSIONS: This study revealed that our understanding of the link between gastrointestinal microbiome and associated diseases has evolved dramatically over time. The emerging new therapeutic targets in gut microbiota would be the foci of future research.
    Keywords:  Co-citation analysis; Dysbiosis; Gastrointestinal microbiome; Research foci
    DOI:  https://doi.org/10.1186/s12967-019-1810-x
  4. Pediatr Neurosurg. 2019 Feb 20. 1-13
      BACKGROUND/AIMS: We sought to describe pediatric "big data" publications since 2000, their statistical output, and clinical implications.METHODS: We searched 4 major North American neurosurgical journals for articles utilizing non-neurosurgery-specific databases for clinical pediatric neurosurgery research. Articles were analyzed for descriptive and statistical information. We analyzed effect sizes (ESs), confidence intervals (CIs), and p values for clinical relevance. A bibliometric analysis was performed using several key citation metrics.
    RESULTS: We identified 74 articles, which constituted 1.7% of all pediatric articles (n = 4,436) published, with an exponential increase after 2013 (53/74, 72%). The Healthcare Cost and Utilization Project (HCUP) databases were most frequently utilized (n = 33); hydrocephalus (n = 19) was the most common study topic. The statistical output (n = 49 studies with 464 ESs, 456 CIs, and 389 p values) demonstrated that the majority of the ESs (253/464, 55%) were categorized as small; half or more of the CI spread (CIS) values and p values were high (274/456, 60%) and very strong (195/389, 50%), respectively. Associations with a combination of medium-to-large ESs (i.e., magnitude of difference), medium-to-high CISs (i.e., precision), and strong-to-very strong p values comprised only 20% (75/381) of the reported ESs. The total number of citations for the 74 articles was 1,115 (range per article, 0-129), with the median number of citations per article being 8.5. Four studies had > 50 citations, and 2 of them had > 100 citations. The calculated h-index was 16, h-core citations were 718, the e-index was 21.5, and the Google i10-index was 34.
    CONCLUSIONS: There has been a dramatic increase in the use of "big data" in the pediatric neurosurgical literature. Reported associations that may, as a group, be of greatest interest to practitioners represented only 20% of the total output from these publications. Citations were weighted towards a few highly cited publications.
    Keywords:  Administrative databases; Big data; Outcomes; Pediatric neurosurgery
    DOI:  https://doi.org/10.1159/000495790
  5. Int J Gynecol Cancer. 2017 May;27(4): 813-818
      OBJECTIVE: The objective of this study was to demonstrate that the construction of the Gynecologic Cancer InterGroup (GCIG) has increased collaboration and accrual to high-quality phase 3 trials at a global level.MATERIALS AND METHODS: The GCIG is a collaboration of 29 international cooperative clinical trial groups committed to conduct of high-quality phase 3 trials among women with gynecologic cancer. A complete bibliography of the reported phase 3 trials has been developed and is available on the GCIG Web site http://www.gciggroup.com. A "GCIG trial" is a trial in which any 2 or more GCIG member groups are formally involved. We reviewed the output of the GCIG from 1997 to 2015 with respect to member participation and quality of publication (impact factor and citation index). The publications are considered in 3 cohorts, 1997 to 2002, 2003 to 2008, and 2009 to 2014, for the purposes of comparison and progress. A social network map has been developed for these publications to identify how the GCIG has increased capacity for clinical trials globally.
    RESULTS: Using a global map, the number of member groups in the GCIG has increased in each of the 3 periods. The total annual number of publications and citations within the 1997 to 2015 period has increased significantly. The average number of citations per publication is demonstrated in each of the 3 periods. The steady increase in the number of citations is used as a proxy for the impact of the publications. The impact factor of the journal and the number of citations are reported for the 10 most highly cited publications. Finally, using a social networking methodology, networking has visibly and numerically increased in each of the 3 periods.
    CONCLUSIONS: Evidence supports that the construction of the GCIG has increased collaboration and accrual to high-quality phase 3 trials at a global level among women with gynecologic cancer.
    Keywords:  Gynecologic cancer; International clinical trials; Networks
    DOI:  https://doi.org/10.1097/IGC.0000000000000934
  6. World J Mens Health. 2019 Feb 20.
      PURPOSE: Male infertility is emerging as a major, escalating global health problem that imposes the need to investigate research trends in male infertility. The purpose of this study is to analyze male infertility research trends in the past 20 years using the bibliometric database from Scopus.MATERIALS AND METHODS: In order to perform an in-depth bibliometric analysis, we propose a 'Funnel Model', which includes several layers representing different sub-areas of male infertility research. Adopting this Funnel Model, using Scopus, we retrieved relevant bibliometric data (articles per year, authors, affiliations, journals, and countries) for various areas of male infertility research and performed descriptive statistics.
    RESULTS: The bibliometric analysis showed an exponential increase in male infertility research in the last 20 years. USA dominated in research output, with Agarwal, A. as the most prolific researcher. Testicular cancer, obesity and metabolic syndrome, and azoospermia were found to dominate male infertility research, whereas erectile dysfunction and unexplained male infertility had lesser attention. Interestingly, prognostic/diagnostic and mechanistic studies have significantly increased in parallel over the last 20 years. Furthermore, our bibliometric analysis revealed fewer publications in proteomics, transcriptomics and metabolomics when compared to genomics. Also, an increasing trend in publication was seen in assisted reproductive technology (ART) research.
    CONCLUSIONS: An integrated and steep escalation in the field of omics and ART research appears to be a prerequisite for further development of future diagnostic and therapeutic strategies for male infertility.
    Keywords:  Bibliometric analysis; Diagnosis; Infertility, male; Prognosis; Publications
    DOI:  https://doi.org/10.5534/wjmh.180114
  7. Ther Adv Psychopharmacol. 2019 ;9 2045125318820207
      Objective: A bibliometric study was undertaken of peer-reviewed publications on atypical antipsychotic drugs (AADs) from the United Kingdom and the findings are presented herein.Methods: We selected the documents from the Scopus database. We applied several production and dispersion bibliometric indicators, including Price's law on the growth of the scientific literature, and Bradford's law. We also calculated a so-called 'participation index' across different countries. The bibliometric data were thereafter correlated with social and health data from the UK, including total per capita expenditure on health and gross domestic expenditure.
    Results: A total of 4156 original manuscripts were published within the timeframe 1967-2015. Our results are in accord with Price's law, with scientific output demonstrating exponential growth (r = 0.9227, as against an r = 0.8766 after adjustment). The drugs most widely evaluated were clozapine (465 documents), olanzapine (263) and risperidone (248). Stratification into Bradford zones produced a nucleus represented by the Journal of Psychopharmacology (168 articles) and British Journal of Psychiatry (159 articles). A total of 1250 different journals were evaluated.
    Conclusions: Publications on AADs in the UK have shown exponential growth across the studied period, which is in line with the progressively burgeoning novel AAD releases. No evidence of a saturation point was observed.
    Keywords:  United Kingdom; atypical antipsychotic drugs; bibliometrics; schizophrenia
    DOI:  https://doi.org/10.1177/2045125318820207
  8. J Vet Med Educ. 2019 Feb 26. 1-9
      Despite increasing representation of women in veterinary medicine, gender differences persist in pay and attainment of senior and leadership positions. In academia, scholarly publication is a measure of productivity and is emphasized in the promotion process. This study aimed to analyze gender differences in the authorship of veterinary research articles to understand factors that could influence women's advancement and standing in academic medicine. We hypothesized that the proportion of women authors would increase between 1995 and 2015 and be similar to employment rates of women in academia, and that gender differences would exist in authorship by species, veterinary specialty area, and role (junior versus senior author). We examined 2,086 articles published in eight prominent veterinary journals in 1995 and 2015, determined the gender of first authors, corresponding authors, and senior authors, and collected article information including study design, species, and veterinary specialty area. The proportions of women first and corresponding authors increased significantly between 1995 and 2015, and in both years studied, women authored a larger percentage of articles than the reported percentage of women working in academia. In 2015, women were first authors of 60.0% (95% CI 56.9-63.0) of articles but accounted for only 38.3% of senior authors (95% CI 33.4-43.3). Female first authors were concentrated in articles pertaining to small animal, equine, and internal medicine disciplines and under-represented among articles pertaining to livestock or surgical specialties. The gender gap in the authorship of veterinary clinical research articles has improved dramatically over the past 20 years, although gender disparities persist.
    Keywords:  academic affairs; advising; authorship; diversity; leadership
    DOI:  https://doi.org/10.3138/jvme.1017-141r
  9. Can J Anaesth. 2019 Feb 25.
      PURPOSE: Females remain under-represented in academic anesthesiology. Our objectives were to investigate gender differences over time in the first and last authors of published articles as well as corresponding citation rates in the Canadian Journal of Anesthesia (CJA).METHODS: We conducted a cross-sectional, retrospective analysis of first and last authors' gender from editorials and original articles published in the CJA in a sample of one calendar year of each decade between 1954 to 2017. We analyzed the relationships between author gender, year of publication, article type, and number of citations.
    RESULTS: Out of 639 articles identified, 542 (85%) were original investigations and 97 (15%) were editorials. Where gender could be confidently identified, the majority (461/571, 81%) of first authors were male. Although there was an increase in the proportion of female first authors over time, this increase was outpaced by the overall increase in female anesthesiologists in Canada. Original articles received more citations and were more likely to have a female first author than editorial articles were. An original article with a female first author resulted in 0.34 (95% confidence interval, 0.28 to 0.39; P < 0.001) more citations per article than a male first author when adjusting for year of publication.
    CONCLUSIONS: Our study shows that, despite a slow increase over time, female authors are under-represented relative to male authors in the CJA and relative to the changing demographics of anesthesiologists in Canada. The reasons for this disparity are multifactorial and further research is needed to identify effective solutions.
    DOI:  https://doi.org/10.1007/s12630-019-01328-5
  10. J Endod. 2019 Mar;pii: S0099-2399(18)30797-0. [Epub ahead of print]45(3): 272-280
      INTRODUCTION: Scientometric analyses outline the research output in a field and, therefore, help researchers and funding agencies to focus more on underinvestigated areas and make more efficient decisions related to public health. The aim of this study was METHODS: Electronic searches were done in MEDLINE and Scopus databases using specified search criteria. All articles related to the field of regenerative endodontics until December 2017 were included. The total number of publication/year and the yearly growth rate of publications were calculated. The following data were extracted and analyzed: authors, country of origin, journal, number of citations, study design, and level of evidence (LOE). The visualization maps for authorship/coauthorship, citations, and country of origin of articles were prepared and analyzed.RESULTS: A total of 694 articles were included. The average yearly growth for publications was 40.4% between 2007 and 2017. The highest number of articles were ex vivo/in vitro (n = 342, 49.27%). The distribution of articles based on LOE was as follows: LOE 1, 8.34%; LOE 2, 6.00%; LOE 3, 0.66%; LOE 4, 11.67%; and LOE 5, 73.33%. Collectively, 1820 authors contributed to the publications included in this study: 1001 authors within 40 collaborating clusters and 819 authors within 149 noncollaborating clusters. The United Sates was the lead country regarding the number of publications, citations, and international collaborations. The Journal of Endodontics published the highest number of articles.
    CONCLUSIONS: The total number of publications in the field of regenerative endodontics shows exponential growth in the past decade. However, the proportion of articles with LOE 1 is low. The research groups around the globe are encouraged to focus their collaborative efforts on higher-quality and clinically oriented research.
    Keywords:  Bibliometric analysis; pulp regeneration; regenerative endodontics; scientometric analysis
    DOI:  https://doi.org/10.1016/j.joen.2018.11.010
  11. Global Health. 2019 Feb 27. 15(1): 17
      BACKGROUND: Scientific cooperation is one of the effective methods to access current knowledge and technologies and also to use successful experiences of researchers in developed countries by academicians living in developing countries. This study aimed to determine the level of international contribution in compilation of scientific articles in Iranian journals published in the field of environmental health engineering.METHODS: This descriptive and retrospective study was conducted within a 10-year period (2008-2017), in which all articles published in five specialized Iranian journals of environmental health engineering were reviewed using a researcher-made checklist. The information collected in the checklist included: the year of publication, number of issues and articles, information about the status of authors' participation in terms of number of authors, sex, institutional affiliation, country, continents, and research centers. Descriptive and inferential statistics such as index of dispersion, measures of central tendency, and Chi-square and t tests were used to statistically analyze the data. Besides, VOSviewer software was used to visualize the data.
    RESULTS: The review of 1276 articles published in 102 issues of the five journals of environmental health engineering in Iran showed that 184 articles were written with the participation of researchers from other countries. Most articles with the participation of international authors during the last decade were published in 2014. Chi-square test indicated a significant difference in the publication of these articles within 2014-2015 than other years (P = 0.001). Among the five journals, the best participation of international researchers was observed in J Environ Health Sci Engineer (168 articles, 91.3%). Considering the number of joint articles with Iran, the top continents were Asia, Europe, and Africa each with 117, 52, and 32 articles, respectively. India, Turkey, and Malaysia had the highest level of cooperation with Iranian researchers with 53, 16, and 14 articles, respectively. 637 authors contributed in 184 articles, of whom 469 (73.6%) were male and 121 (18.9%) were female. T test was used to compare the mean number of male and female authors in the articles with or without the participation of international researchers, which showed no significant difference.
    CONCLUSION: International contribution of researchers in compilation of specialized environmental health articles was good. Given the low level of cooperation between researchers from developed European and American countries and their Iranian counterparts, it seems necessary to adopt different methods to attract more collaboration from researchers working in developed countries considering their significant role in health-related areas.
    Keywords:  Articles; Citation analysis; Environmental health; Journals; Research; Scientific participation; Scientometrics
    DOI:  https://doi.org/10.1186/s12992-019-0460-3
  12. J Long Term Eff Med Implants. 2018 ;28(3): 247-257
      Anterior cruciate ligament (ACL) injuries continue to be a major focus in sports medicine research. With so many changes to our understanding of ACL anatomy and with rapid advances in reconstruction techniques and rehabilitation protocols within the past 20 years, it is important to identify the landmark research that has laid the foundation for current ACL treatments. Using the Web of Science citation index, a search was carried out for the 30 most cited articles on ACL injury published in the last 20 years. The generated list was sorted from highest to lowest citation number. Clinical studies were subcategorized as therapeutic, prognostic, diagnostic, or economic/decision analysis and assigned a level of evidence. Basic science articles were designated anatomic, animal, biomechanical, or clinical. The number of citations per year (citation density) was calculated. The search yielded 6,345 articles. The total number of citations among the top 30 ranged from 188 to 611. Citation density ranged from 10.1 to 66.2. Nineteen articles were clinical, 8 were basic science, and 3 were video analyses. Clinical articles were most commonly therapeutic (18 of 19; 95%). Basic science articles were most commonly biomechanical (7 of 8; 88%). The most common level of evidence was Level II (10 of 19; 53%). More than half of the articles in the top 30 (16 of 30; 53%) were published in The American Journal of Sports Medicine. Many of these articles have played a large role in shaping current clinical practice regarding ACL injuries. We hope that by compiling this list we can draw attention to the continued need for studies of the highest level of evidence.
    DOI:  https://doi.org/10.1615/JLongTermEffMedImplants.2018029379
  13. Front Pharmacol. 2019 ;10 108
      Background: In recent decades, research on drug therapy for ventilator-associated pneumonia (VAP) remains one of the major hot-spots in the field of critical care medicine, but relevant data are not satisfactory. Our aim was to assess the status and trends of the most cited articles on drug therapy for VAP through bibliometric approaches. Methods: The Institute for Scientific Information (ISI) Web of Science core collection database was searched for the VAP-related articles. The time period for retrieval was from the beginning of the database to September 30, 2018. The top 100 most cited articles were selected to obtain their information on the authors, title, publication, number of citations, author's affiliations, country, etc. These general information and bibliometric data were collected for analysis. VOSviewer software was used to generate a term co-occurrence graph that visualized a reference pattern for different terms in the 100 articles. Results: The number of citations for the 100 selected articles ranged from 142 to 3,218. These articles were published in 31 different journals. The top three journals in terms of the number of our selected articles they published were "Critical Care Medicine" (17 articles), "American Journal of Respiratory and Critical Care Medicine" (11 articles) and "Clinical Infectious Diseases" (10 articles). The most frequently nominated author was Marin H. Kollef from the University of Washington, and of the top 100 articles, 16 listed his name. These top 100 articles were published after the year of 2000. The most common type of article in the top 100 was an original article (53%). The United States and France were the countries that contributed the most articles to the top 100. Gram-negative bacilli, pseudomonas aeruginosa, antibiotics, risk factors and other terms appeared more frequently, suggesting that attentions on this issue currently focused on the rational application and management of antibiotics. Conclusion: This study analyzed the 100 most cited articles on drug-treated VAP, and provided insights into the historical developments and characteristics of the most cited articles in the field of VAP.
    Keywords:  VOSviewer; antibiotics; bibliometrics; drug therapy; ventilator-associated pneumonia
    DOI:  https://doi.org/10.3389/fphar.2019.00108
  14. PeerJ. 2019 ;7 e6411
      Background: Fecal microbiota transplantation (FMT) is an emerging therapy against Clostridium difficile infection (CDI) and inflammatory bowel disease (IBD). Although the therapy has gained prominence, there has been no bibliometric analysis of FMT.Methods: Studies published from 2004 to 2017 were extracted from the Science Citation Index Expanded. Bibliometric analysis was used to evaluate the number or cooperation network of publications, countries, citations, references, journals, authors, institutions and keywords.
    Results: A total of 796 items were included, showing an increasing trend annually. Publications mainly came from 10 countries, led by the US (n = 363). In the top 100 articles ranked by the number of citations (range 47-1,158), American Journal of Gastroenterology (2017 IF = 10.231) took the top spot. The co-citation network had 7 co-citation clusters headed by 'recurrent Clostridium difficile infection'. The top 7 keywords with the strongest citation bursts had three parts, 'microbiota', ' diarrhea ', and 'case series'. All keywords were divided into four domains, 'disease', 'nosogenesis', 'trial', and 'therapy'.
    Conclusions: This study shows the research performance of FMT from 2004 to 2017 and helps investigators master the trend of FMT, which is also an ongoing hotspot of research.
    Keywords:  Bibliometric analysis; Citations; Clostridium difficile infection; Fecal microbiota transplantation; Inflammatory bowel disease
    DOI:  https://doi.org/10.7717/peerj.6411
  15. Medicine (Baltimore). 2019 Feb;98(8): e14523
      BACKGROUND: Rheumatoid arthritis (RA) is a worldwide health issue; although the prospects for most patients are favorable, many still do not respond to the current therapies. Numerous articles related to RA have been published in the past 3 decades; an analysis of the most cited articles in this field was undertaken to identify important articles regarding RA related to pathogenesis, diagnosis, and treatment.METHODS: We searched the Web of Science and collected the general information of the top 100 cited articles. The citation number, publication year, authorship, impact factor (IF) of the journal in the publication year, country origins, article types, and funding source were evaluated.
    RESULTS: The total citations of the top 100 articles varied from 11,922 to 556 and were published between 1985 and 2014. These articles were published in 24 journals, led by Arthritis and Rheumatism (n = 33), followed by the New England Journal of Medicine (n = 15). Most of the articles (n = 80) were produced by ≥5 authors. They were from 34 countries, and the United Stated contributed to most of the articles (n = 58), followed by the United Kingdom (n = 42). The article types were divided into clinical study (n = 55), review (n = 17), meta-analysis (n = 4), clinical guideline (n = 10), and basic science (n = 14). Eighty-seven percent of the articles were supported either by public organizations or medical companies.
    CONCLUSION: This study provided insights into the development of publications and their citations of RA in the past 3 decades. Clinical studies or clinical guidelines published in high-impact journals were more likely to be cited in the field of RA. The latest publications may not be included in the top 100 cited articles, as the more recent studies have not had sufficient time to accumulate the number of citations.
    DOI:  https://doi.org/10.1097/MD.0000000000014523