Visualizing highly cited scientific output of Indian physiotherapists : A bibliometric study [ version 1 ; peer review : awaiting peer review ]

Physiotherapy research supports the advancement of Background: evidence-based practice and development of a highly skilled workforce. This study aims to visualize highly cited scientific output of Indian physiotherapists from 1999 to 2018. A descriptive study design was adopted to visualize highly cited Methods: scientific output of Indian physiotherapists using the Web of Science (WoS) database from 1999 to 2018. A search was carried out using the following term "((TS=(physiotherapy) OR TS=("physical rehabilitation") OR TS=("physical therapy")) AND AD=(India))Indexes=SCI-EXPANDED, SSCI, A&HCI, CPCI-S, CPCI-SSH, ESCI, CCR-EXPANDED, IC Timespan=1999-2018”. Data collected were analyzed using Incites from WoS and VOSviewer software. A total of 489 articles were published between 1999 and 2018, Results: with a peak of 103 in 2016 with 2420 citations. A decline in publication count was observed after 2016. The journal International Journal of published the highest number of articles (n=35). Manipal Physiotherapy University (n=26) was found to be the most active institution for physiotherapy research in India, as determined by producing the most articles. Indian physiotherapists published the highest number of research articles in collaboration with US authors (n=24). There is an increasing trend in the scientific output of Indian Conclusion: physiotherapists over the past two decades; however, a decline is observed after 2016. It is recommended that research collaborations across the globe are increased and scientific output should be improved, leading to a higher number of citations. Future research should explore factors influencing 1 2 3 1 4 1 1


Introduction
Scientific output of a profession is recognized by the frequency of publications, which are published in peer-reviewed journals and indexed in bibliographic databases [1][2][3] . In physiotherapy, this scientific output is utilized to enhance existing knowledge and develop guidelines for highly effective clinical practice 4 . Accordingly, the analysis of scientific output allows definition of baseline indicators in knowledge and clinical practice in physiotherapy 5,6 . Various studies investigated the scientific output of physiotherapists across the globe [6][7][8][9][10][11][12][13][14] . Among these studies, several utilized electronic searches 6,7,[9][10][11]13,14 , whereas others were limited to document reviews 8,12 . Concerning the Indian context, only two studies have been performed to reveal the research productivity of Indian physiotherapists from 2000 to 2014, which were limited to the Medline database 10,11 . Moreover, Li et al. (2018) recently stated that Clarivate Analytics's Web of Science (WoS) is the World's foremost scientific citation search and analytical platform, which can be used as both a research tool and dataset 15 . Hence, there is a need for further research that should involve the WoS database to detect high-quality research publications by Indian physiotherapists up until 2018 (this study took place in 2019). Therefore, this study intended to conduct a bibliometric study on the scientific output of Indian physiotherapists using WoS during the last two decades (from 1999 to 2018).

Methods
A descriptive study design was adopted to reveal the scientific output of Indian physiotherapists using an electronic literature search in the WoS database during the period from 1999 to 2018.

Article selection
The search was conducted on 14th October 2019. The term 'Indian physiotherapists' denotes physiotherapy professionals employed in any of academic or clinical establishments in India in the study period. The search was carried out in WoS using the following term "((TS=(physiotherapy) OR TS=("physical rehabilitation") OR TS=("physical therapy")) ANDAD=(India)) Indexes=SCI-EXPANDED, SSCI, A&HCI, CPCI-S, CPCI-SSH, ESCI, CCR-EXPANDED, IC Timespan=1999-2018". The search started from 1999 since this study aimed to retrieve data from the past two decades.

Article screening
The search methodology is described in Figure 1. Based on the inclusion criteria, 489 publications were included and proceeded for further analysis.

Data analysis
Retrieved articles were analysed using Incites in WoS and VOSviewer 1.6.11. Incites was used to gather information publication year, authorship ranking, source journal productivity, collaborating institutions, country-wise research collaboration, and citations. In addition, the information related to h-index was obtained from the Incites in WoS. The data, which is exported from the WoS database as an ISI common export (.ciw) format, were imported into VOSviewer to explore the co-occurrences of keywords used by the authors in their articles. The flowchart describing the procedures for carrying out both Incites and VOSviewer analysis is depicted in Figure 2.
Since Incites in WoS used in this study are proprietary software, the researchers could alternatively use a tab-delimited file downloaded from WoS and use it in VOSviewer.

Results
A total of 489 articles were included in the study; 381 research articles, 53 reviews, 34 proceedings, 9 meeting abstracts, 8 letters, 3 editorial material, and one correction.
Between 1999 and 2008, scientific output of Indian physiotherapists is minimal, reaching a peak of 9 in 2008. Subsequently, the publication count starts to rise gradually from 2009 to 2016, which has a peak of 103 articles. Publications decreased after 2016 and rose slightly in 2018, but not to levels seen in 2016 (Table 1 and Figure 3). Regarding citation count, there was a gradual rise over the research period, with a total of 2420 citations between 1999 and 2018, more than 100 of which have been documented since 2012. The highest average citation (citations/article) of ≥10 was observed only in 2006 (mean, 11.00) and 2014 (mean, 10.20).
A total of 264 journals had published the 489 retrieved articles. The top 20 journals in which Indian physiotherapists published over the study period are displayed in Table 2. The top 20 journals published 174 articles, 35.58% of total publications (N=489) in the research period. Out of the top 20 ranked journals, 11 were journals based in India, 26.79% of the total publications.
The International Journal of Physiotherapy published 35 articles, with six citations for these 35 articles, an average citation of 0.17. It was the most active journal found in this study and contributed to 7.16% of total publications. In contrast, the journal Haemophilia published seven articles with 68 citations     Using VOSviewer, the authors created a keyword table and graphic representation of the co-occurrence of keywords across articles. The top 20 keywords used in articles (from a total of 2477 keywords) are shown in Figure 4. An article's keyword may represent its primary material, and to some degree, the frequency of occurrence. Likewise, co-occurrence can indicate centered themes of research in a field. Among the top 20 keywords, those with a considerable rate of occurrence are "Physiotherapy" (n=72; 2.91%), "Rehabilitation" (n=48; 1.94%), "Management" (n=46; 1.86%), and "Exercise and Therapy" (n=25; 1.01%). The keyword "Randomized Controlled-Trial" had the highest average citations (16.50%) among the top 20 keywords.

Publication count
Previously, using data from Scopus, it had been observed that Italian physiotherapists published 1083 articles with 13,373 citations. The number of publications by these authors had gradually increased over the years from before 1995 (10 articles) to 2016 (143 articles). More than 50% of the total publications were produced between the years 2012 and 2016 13 [16][17][18] , and improves the quality of their scientific output 19 . Furthermore, earlier studies have also stressed the importance of international research collaboration in health care, and it is frequently regarded as an indicator of quality to develop and disseminate scientific knowledge to newly developing countries 20,21 .

Collaborating authors
Keywords by co-occurrence Lastly, this study revealed the top 20 keywords that occurred in various articles using VOSviewer software. The term "Physiotherapy" had the highest occurrence rate (2.91%). "Randomized controlled trial" was associated with the highest average citation (16.50).

Conclusion
This study observed that the scientific output of Indian physiotherapists shows an uptrend in performance since 1999, excluding 2017/18 where a drastic decline was noticed. Indian physiotherapists are mostly publishing and collaborating with Indian-based journals and institutions, respectively. Even though there are high-quality publications, there is a need to enhance both the quality and quantity of scientific papers, to increase the high number of citations and average citation. This study also recommends that Indian physiotherapists should expand their research collaboration internationally to improve their scientific output. Future studies can focus on analyzing individual and institutional factors influencing research productivity of Indian physiotherapists and develop suitable strategies to enhance their scientific production. This project contains the following underlying data: -Article level and citation data for all 489 articles retrieved.

Data availability
-Journal, author, institution and country data for all 489 articles retrieved.
Data are available under the terms of the Creative Commons Zero "No rights reserved" data waiver (CC0 1.0 Public domain dedication).