Tendency and foci of nurse practitioners:bibliometric analysis based on the CiteSpaceV?

Qi Hung,Qi-Rong Hung,Qiu-Xi Liu,Si-Ping Yu,Hong-Yn Sun,*

aSchool of Nursing,Southwest Medical University,Luzhou,Sichuan 646000,China

bDepartment of Respiratory Medicine,Affiliated Hospital of Southwest Medical University,Luzhou,Sichuan 646000,China

Abstract: Objective:Nurse practitioners (NPs) have drawn significant attention recently and played a major role in healthcare.We aim to find the evaluation of NPs through published studies and then visualize the research status and hotspots in this field.Methods:All data came from the Web of Science Core Collection,and the data were counted and entered into Excel 2016.The key documents nodes were excavated by analyzing the knowledge network map using CiteSpaceV software.In this study,these nodes of“author,country,institution,keyword,co-citation (referencecited-authorcited-journal),and grant” were harvested for analysis and comparison.Results:A total of 4912 records,which were published between 2007 and 2018 and pertained to NPs,were retrieved from the Web of Science Core Collection database (WoSCC) from a diversity of languages.The total and the annual number of publications and citations of these continually increased over time.Most publications were in 2018 (618 records).This study involved 8241 authors located in 98 countries and 4557 institutions totally.The United States (2737 records) and the University of Michigan (90 records)dominated in publication frequency.There are 902 journals and 2449 articles with funding support that have been analyzed.Most articles were from JAMA:The Journal of the American Medical Association (1386,IF=47.661),followed by the Journal of Advanced Nursing (1359,IF=2.267),and The New England Journal of Medicine (1109,IF=79.258).The reference “The Role of Nurse Practitioners in Reinventing Primary Care” was co-cited most frequently,which revealed it as the highest landmark article in NP.The top-ranked keyword was “Care,” other than “Nurse practitioner,” which has an ultra-high frequency.Some of the high-frequency keywords represent the significant direction of NPs.Conclusions:NPs are at the crux of health-care delivery and play an important role in providing high-quality nursing.Publications on NPs in WoSCC have increased notably during the recent years,and have appeared in some journals that have a high impact factor.Research frontiers and developmental trends were revealed by the analysis in this study,which can be used to forecast future research developments in NPs and taken as a reference to choose the right directions by subsequent researchers who wish to use these results.However,the grant support from administration or research institutions is still in need of improvement and the scope of research in NPs should be broadened in the future.

Keywords: bibliometric analysis ? CiteSpace ? mapping knowledge domain ? nurse practitioners ? visualization ? Web of Science core collection

1.Introduction

Nurse practitioners (NPs) are Advanced Practice Registered Nurses who have additional responsibilities for administering patient care as compared to Registered Nurses (RNs).1The concept NPs originated in the United States.2,3To date,many countries that have developed NPs-related talent training.To be a NP,one needs to go through the following 3 steps:Step 1,become a practicing RN and take a minimum of 2 years to complete the master of nursing (MSN) program,which is a necessary condition to be an NP.4Step 2,continue to maintain the NP license and earn the BSN (Bachelor in Nursing Science) degree.If you have already earned a Bachelor of Nursing,you can skip “step 2,”fortunately.Step 3,earn the advanced practice nursing licensure in practical nursing through exam and certification requirements.Individuals successfully satisfying these requirements would work as an NP in hospitals,nursing homes,and other health-care or medical facilities,after completing the steps outlined above.Nonetheless,some NPs choose to take a step back from hands-on patient care to pursue managerial or administrative positions.1,5NPs include General NP,Certified Registered Nurse Anesthetist,Gerontological NP,Psychiatric NP,and Family NP.In the United States,NPs provide high-quality care in rural,urban,and suburban communities,and in many scenarios,including clinics,hospitals,emergency rooms,urgent care sites,private physicians or NP practices,nursing homes,schools,colleges,and public health departments.NPs provide the following services:(1) diagnosing and treating acute and chronic conditions;(2) managing patients’overall care;(3) educating patients on disease prevention and positive health and lifestyle choices;and(4) prescribing medications and other treatments.The specialty areas include (1) acute care,(2) adult health,(3) family health,(4) gerontology health,(5)neonatal health,(6) oncology,(7) pediatric/child health,(8) psychiatric/mental health and (9) women’s health(American Association of Nurse Practitioners 2012-2019).The origin of the NPs role in Canada lies in the work of nurses who,decades ago,provided care in rural and remote areas.6They provide comprehensive health assessment,diagnose,treat,and manage acute and chronic diseases.

The Canadian NPs consisted of practitioners,consultants/collaborators,leaders,and researchers,and they may also work collaboratively with interprofessional teams,other health-care providers,and community members.7Canadian Nurse Association6,8has mentioned that they have developed the RN Prescribing Framework which has been compiled based on the NP’s experience of practicing and other countries implementing RN prescribing are supported by country,provinces,and regions.8In Australia,after finishing their program,RNs will become NPs.9,10In accordance with Australian Nursing and Midwifery Council Policy,NPs should obey the following standards:NP (1)assesses using diagnostic capability,(2) plans care and engages others (3) prescribes and implements therapeutic interventions,and (4) evaluates outcomes and improves practice.9According to an Israeli study,as NPs do have a positive impact on the overall health of patients,there is a strong willingness to integrate nurses into healthcare.11However,NPs have an emerging role in development in China,even though there are some achievements about NPs in Taiwan and Hong Kong,few hospitals in the mainland have started to try NPs.The concept,courses setup,education,role function,registration,and certification of NPs are not been exactly defined.12,13To summarize,NPs of various countries around the world are as professional as they are in developing health-care delivery.Therefore,there is an increasing number of literature reports in this field,and so more and more relevant literature need to be continuously searched and read by relevant researchers.The purpose of the study is to comb the current situation and trends of NPs and analyze the relevant literature in the Web of Science Core Collection (WoSCC) database using CiteSpaceV software.

2.Data and methodology

2.1.Data collection

The data of this bibliometric study came from the WoSCC database,which includes Science Citation Index Expanded,Social Sciences Citation Index,and Arts and Humanities Citation Index.

To explore the trends in NPs,we retrieved NPsrelated studies published from 1986 to 2018 (as literature cannot be fully covered until 2019) in the WoSCC database.The index topics included “Nurse Practitioners,” “Nursing,” “Nurses,” “Practical,” and “Private Duty.” And the retrieval strategy is as follows:TS=(“Practical” and “Nurses”) OR (“Practical” and “Nursing Care”) OR “Nursing,Private Duty” OR “Nursing,Practical,” OR “Nurse Practitioners.” All studies were retrieved and downloaded on June 20,2019.Simultaneously,the“fully documented and cited references” of literature were exported in the “other file formats” using the format of “plain text”.The types of documents downloaded are “review” and “articles” and no language-related restrictions were applied to the search.All the searched records were exported to CiteSpaceV software for further analysis,and then all results were organized using Excel 2016.

2.2.Method of analysis

Not only the bibliometric analysis but also the visualization of literature is used widely to analyze the relevant research data in many research fields,such as psychometric,nanotechnology,aviation engineering,economic geography,ecological security and science,strategic management,and technology policy analysis.14However,the bibliometric analysis about nurses,especially the NPs,still produced only sparse results.In order to explore more about the development tendency and hotspots in this field,the CiteSpaceV software has been used in the visualization related to NPs.CiteSpaceV is a software used in literature metrology.Using it,we can identify the literature and information visualization in many knowledge domains.It was developed by the team of Chaomei Chen of Drexel University,US,using Java program.15The CiteSpaceV is inspired by Thomas Kuhn’s structure of scientific revolutions that centers on the change of research focus over time,sometimes incrementally or rapidly.Recently,CiteSpaceV has also been used in medicine sometimes.However,the nursing-related articles are relatively few.There were only 546 published papers16-18that were related to clinical nursing,nursing education,palliative care,and midwifery.

Based on what has been analyzed above,we made a bibliometric analysis of the literature on NPs using CiteSpaceV.Many visual items were used in our study,for example,(1) the analysis of citation and co-citation can help us to detect hot-topics in the field which we focus on;(2) although this metric—which can be found in every project—is burst,it is a normal one;however,it is very important to do a burst detection algorithm to identify emergent research-front concepts,reference and authors,and so on;19(3) centrality is an important index of visual analysis,which can be used to measure and highlight the potential pivotal points in some research fields;20(4) in addition,through the analysis of author,country,and institutions,we can detect the one that is the pivotal-point,and that will be provided as the reference for us to get cooperation.The results of our study are as follows.

3.Results

3.1.Brief description of the publication and citation tendency

The initial search identified 4912 entries,including 4547 articles (92.57%) and 365 reviews (7.43%).Furthermore,it contains 15 languages,such as English(4802,97.76%),German (30,0.61%),and Portuguese(16,0.33%);and English has the highest entries.Out of the 4912 studies,the first article on NPs was published in Belgium by De Becker21in 2007 in a series of books,which are entitledContributions to Nephrology,and the title of the paper is “Starting Up a Continuous Renal Replacement Therapy Program on ICU.”The latest one is a cohort study that was published in the US by the authors Jackson GL.22The topic of this paper was “Intermediate Diabetes Outcomes in Patients Managed by Physicians,Nurse Practitioners,or Physician Assistants:A Cohort Study” in the journalAnnals of Internal Medicine.We know that the number of studies in this field has increased rapidly from 2007 to 2018,especially in the recent 3 years (1698,34.57%).The citation frequency of the papers shows the degree of influence.As we can see,the citation counts of NPs have been increasing fast,this being the case especially in 2018 (9083) (Figure 1).Overall,the publication tendency of papers is steadily increasing,and the citation count of these papers is increasing rapidly.

Figure 1. The tendency of publication records and citations related to Nurse Practitioners (2007-2018).

3.2.Author analysis

In this section,we analyzed the publication and citation frequency of authors and list the top 10,as shown in Table 1.As we can see,the high-productive author is Gardner G (24,0.49%) in this research field according to the number of papers.In addition,the strength of the burst of Gardner G (burst 5.26,2015-2018)ranked second among the top 10 authors (Table 1).This indicated or showed that Gardner G was the one who was involved in this research field in recent years and made a contribution to it.Both the citation frequency (464) and the citation frequency per paper(19.33) of Gardner G were more than others.However,based on the result we can get,the centrality of all authors was 0.It was apparent that no core authors group was formed.

Table 1. Publication and citation frequency of the top 10 productive authors.

3.3.Co-institute and co-country analysis

If,in an article,2 or more authors are from the same institute or country,it is referred to as cooperation.In this section,we will analyze the institutes and countries of the authors of these studies.Judging cooperation based on the co-occurrence frequency of institutions and countries,we found the top 10 institutions and countries.First,we must remember that the size of the circle indicates the number of papers published by institutions and countries.The thickness of links represents the linking strength between institutions or between countries.As we can see,the University of Michigan (90,1.83%) is the most productive one among the 4557 institutions and the University of California,San Francisco (88,1.79%) comes second (Table 2).From the centrality of institutions,we can see that Columbia University was higher than others.It was suggested that Columbia University obtained the key position in this field.The result based on countries was as follows:the US (2737,55.72%) is a high-productive country among these 98 countries.It shows that the US and UK (398,8.10%) (Table 3) did well and become more active in this research field.According to the knowledge map of institution and country (Figures 2 and 3),we can see that the links are too thin to show that the linking strength still needs to be reinforced in the future.And the institution named Radboud University Nijmegen was in a highly farther position from the others.It was shown that it lacks relations with others.

Figure 2. Knowledge map of institution related to Nurse Practitioners (2007-2018).

Figure 3. Knowledge map of country related to Nurse Practitioners(2007-2018).

3.4.Co-cited journal and funding analysis

The analysis of journals can help us to find the effectiveness and provide a reference for us to choose the target journals.Results show thatJAMA,a journal of the American Medical Association (IF=47.661) is the most effective one which has counts of citation numbering around 1386,and theJournal of Advanced Nursingfollowed.Half-life of co-cited journals shows the duration of influence.In the top 10 co-cited journals of NPs,the following 3 journals own the highest half-life:Journal of Clinical Nursing(half-life=8),International Journalof Neural Systems(half-life=8),andHealth Affairs(half-life=8) (Table 4).The top 10 co-cited journals,arranged according to the strength of burst,shows that the journalPloS onehas the strongest burst (burst=41.35) (Table 5).Funding support can reflect the firm support of countries for some research fields.From Table 6,it can be seen that some funding institutionssuch as “Agency for Healthcare Research and Quality”(39,0.79%),“National Institute for Health Research”(22,0.45%),and “National Institutes of Health” (17,0.35%) had supported many papers dealing with NPs compared to other grants.We not only pay attention to the frequency of funding support but also care about the half-life.Half-life brought out the significance of time-duration of grant support,which can be taken as a reference to researchers to obtain the necessary funding support to ensure that their project work proceeded well.Among the top 10 funding institutions the“National Institutes of Health” (half-life=9),“National Institute on Aging” (half-life=9),and “Canadian Institutes of Health Research” (half-life=9) provided continuous support in this field.In addition,their support frequency is also very good.

Table 2. Publication and citation frequency of the top 10 productive institutions.

Table 3. Publication and citation frequency of the top 10 productive countries and regions.

Table 4. The top 10 co-cited journals of NPs according to the citation frequency.

Table 5. The top 10 co-cited journals of NPs according to the strength of burst.

Table 6. The top 10 funding institutions according to the frequency.

3.5.Co-cited references and keywords analysis

The analysis of the co-cited references,especially the citation burst,can show a significant increase in the fields in which researchers are interested.This study listed the highest citation count references and their strength of burst from 2007 to 2018 and formed a knowledge map (Table 7,Figure 4).The paper “The Role of Nurse Practitioners in Reinventing Primary Care”23owns the highest citation counts with 72,and was written by Naylor MD,2010.It was published in the journalHealth Affairs(Table 7).In this paper,the author has summarized enough evidence to demonstrate that the NPs contributed to improving primary care and reduced more costly health resources.And the researcher recommended that nurses’ practice should be standardized and the performance results should be publicly reported.The objective of this study is to maximize the highquality care provided by NPs.There is no centrality in the result of co-cited reference analysis,which revealed that they may not have formed the most key document in this research field and that higher-quality studies should be done in the future of NPs.As we can see,the article which has the most strength burst of co-cited reference is “Systematic Review of Whether Nurse Practitioners Working in Primary Care Can Provide Equivalent Care to Doctors” (burst 21.6,2007-2009)24in the top 10 cocited references (Table 7),which is a systematic review that detected whether NPs can provide care equivalent to doctors at the first point of contact in a primary care setting.Also,the researcher holds that although the patients are satisfied with the service of NPs as they are with doctors’ at the point of first contact,further research is needed to confirm that NPs’ care is safe in terms of detecting rare and important health problems.

Keywords can provide an insight into the main research topics in this research field clearly.25From Table 8 and Figure 5,we can see the top 10 keywords according to the occurrence frequency,which is not difficult to detect,are “nurse practitioner” (982),“care”(562),and “nurse” (555),which have the most occurrences.In addition to these,“primary care,” “education,”and “management” are more active in this field of study,and are capable of functioning as the hot-point at present or had done so previously.

Figure 4. Knowledge map of co-cite reference in nurse practitioners.

Figure 5. Knowledge map of keywords related to Nurse Practitioners.(2007-2018).

Figure 6. Keywords with the strongest citation burst.(2007-2018).

Figure 7. The knowledge transfer of nurse practitioners according to the Overlay Maps results.

Table 7. The top 10 co-cited references in NPs according to the citation frequency.

Table 8. The top 10 keywords according to the occurring frequency.

We also analyze the burst strength of the keywords(Figure 6).The strongest burst may be a herald of the new direction in the progress of NPs.As the result shows,the “risk factor” (2010-2014) is the one that owned the highest burst strength,which is the new research point in this field,aimed at facilitating development progress.Furthermore,from “disease” to “diagnosis” is the new direction in this field,because their beginning time is late compared with others.Hence,this result can provide a reference to others who are interested in NPs.

3.6.JCR-overlay analysis

From the overlay maps results,we can mainly analyze the knowledge transfer in this field.26As we can see,it is possible to discern a contrasting picture between the citing base map on the left and the cited base map on the right (Figure 7).As the result shows,there are 2 principal wire bundles,the one from “Medicine,Medical,Clinical” to “Health,Nursing,Medicine”,and the other one from “Psychology,Education,Health” to “Health,Nursing,Medicine.” We can draw a conclusion that the studies on the NPs have taken into account the clinical and nursing aspects,to be their references.Hence,if we continue to do research about NPs,we can pay attention in this direction.

4.Discussion

The development tendency of publications shows that the count of papers is growing every year,from 2007 to 2018 and the average of published papers is 409.33(8.33%).The highest publication count reaches 618(12.58%) in 2018.This suggests that many countries pay attention to the NP in recent years.For instance,Canadian Nurses Association has made relevant rules on NP resources,profiles,exam education,and so on.8American Association of Nurse Practitioners includes clinical resources,practice management,professional development,and practice-related research.12However,there is no such association for NP at present in China.More research should be done in the future to address this issue.

The authors analysis showed that not a core group of authors formed.This may be attributable to the fact that the beginning time in this field is too late.However,there were also many productive authors,like Gardner G,Gardner A,and Hooker RS.

From the perspective of journal analysis,we can see the most productive journal isThe Journal for Nurse Practitioners:JNP(311,6.33%),and its IF is 0.487.Among the top 10 productive journals,the one with the highest IF is theInternational Journal of Nursing Studies(IF=3.656).This indicated that most articles published in journals are at the lower or middle level,although some papers have been published inBMJ,JAMA,Lancet,etc.That may be owing to the lack of nursing journals and the IF of some nursing journals being lower than the others (Science 2019).27Moreover,the concept of NP has been developed only recently,since about 12 years.So,it is a new point compared with other research fields,which needs to be exploited to achieve richer results.

From the results of the co-cited journal,we may make some conclusions as follows:Among the top10 co-cited journals,50% of the journals own the higher IF,which is over 10,such asJAMA:The Journal of The American Medical Association,The New England Journal of Medicine,British Medical Journal,Lancet,andAnnals of Internal Medicine.This became a reference to some related researchers who refer to documents having high quality to get a new point to continue their study.Overall,making great progress in this field is critically essential.

From the results of citation frequency,we can get some effective information.There are some references related to “Primary Care,” which accounted for 50%.The “Primary Care” became mainly a direction and hot point in the research about NPs.In addition,there are few researches which are related to clinical nursing about NP and its further development.Not only “nurse practitioner,” “care,” and “nurse” but also “primary care,”“education,” and “management” have gradually become the principal points at this stage.

From the analysis of country and institution,we can see that the most productive ones were in Europe and north America.This is because nursing care originates from there and their nursing system is more complete than that of others.From the knowledge map of country analysis,the existence of a link between countries can be inferred but the strength of the link is lower.Enhancing the cooperation between countries about NPs is important in the future.Also,it is important to select the development model according to the nation’s conditions,since such a selection would be appropriate for the development of senior NPs.From the visual map of institutions,there are some subjects about NP’s studies,such as “emergency care,”“chronic kidney disease,” “novel approach,” and so on.Especially,the University of Michigan and the University of California,San Francisco have become the vital research centers and others are assembled around them to develop themselves.These 2 centers put forth a good example for others to make progress in the future.

Finally,we analyze the grant of these studies.The “Agency for Healthcare Research and Quality”(39,0.79%),“National Institute for Health Research”(22,0.45%),and “National Institutes of Health” (17,0.35%) own the highest proportion of funding support.In addition,the “National Institutes of Health”is an institution which not only has the highest proportion of funding support but also has long-duration support.That grant is more crucial to a study which affects the continuation of a study and the publication of research findings.Therefore,funding support from governments should last for a long duration if they choose a study that contributes to the development of society and academy.This will promote the development of NP.

5.Conclusions

Since it was too late when the study on NP began(2007),there were no core group of authors formed according to the centrality.In our study,we found that there are some highly productive authors,but they just do some researches themselves or cooperate with their own teammates,and so no team that works internationally has been developed.Furthermore,since the hot topic of research in this field is somewhat narrow,it is necessary to ascertain more points by which we can do multifaceted researches using the available big data and experience.In the future,we can carry out more studies on NPs and do more research to discover some new points.

Limitation

Because the capacity of CiteSpaceV software for data is limited (10,000),there are some data do with the minimum spanning tree and pruning sliced networks.So,the data were simplified,and only then could they authentically reflect the level of development to some extent.

Ethical approval

This study was approved by the ethics committee of Affiliated Hospital of Southwest Medical University (IRB approval number:KY2020005).

Conflicts of interest

All contributing authors declare no conflicts of interest.