Unveiling transplantation research productivity of United States: A bibliometric analysis

Abstract

Background: The United States has witnessed significant advancements in the field of organ transplantation over the course of the last five decades, as demonstrated by a notable increase in the quantity of academic research. The presence of a highly dynamic research environment necessitates continuous evaluations to maintain the integrity and progress of the field.

Aim: To evaluate the total output and thematic emphasis of transplant research conducted in the United States.

Methods: On January 10, 2023, we conducted a bibliometric search of United States research output in transplantation journals from the Web of Science database's Science Citation Index Expanded. We excluded editorials, meeting abstracts, and other non-article types. We analyzed annual trends, authors, institutions, articles, keywords, and countries collaborating with the United States, using VOSviewer 1.6.18 to create figures and tables.

Results: The United States published 25956 papers (3078 reviews and 22878 articles) representing 37.7% of the world's scientific output. Canada emerged as the top collaborator with the United States, co-authoring 1263 articles. Leading institutions in United States transplantation research were the University of Pittsburgh (1749 articles), Mayo Clinic (1605 articles), Harvard Medical School (1549 articles), and Johns Hopkins University (1280 articles). The top three keywords with over 2000 occurrences were "recipients," "survival," and "outcomes," indicating a focus on graft and recipient outcome markers by United States researchers.

Conclusion: Our findings demonstrate the United States leadership in organ transplantation research, contributing significantly to the global scientific output in this field. However, opportunities exist for fostering expansive partnerships, particularly with developing countries. This study provides valuable insights into the transplantation research landscape in the United States, emphasizing the importance of ongoing evaluations to maintain and propel advancements in this critical medical discipline. The results may facilitate future collaborations, knowledge exchange, and the pursuit of innovative solutions in the realm of organ transplantation.

Keywords: Bibliometrics; Organ transplantation; Research output; Scientometrics; United States.

Figure 1

Flow chart of the United States transplantation research output and exclusion criteria.

Figure 2

Publication trends in the United States in the field of transplantation, as documented in transplantation journals from 1998 to 2022.

Figure 3

Network visualization showing most cited countries contributed with the United States in the field of transplantation research. A and B: The size of the circles represents the weight of citations.

Figure 4

Cluster map of the most occurring keywords and their interconnection across the years. A: Each circle represents a keyword, and the size of the circles represents the frequency of occurrence. Larger circles indicate that the keyword appears more frequently. Keywords included in the same cluster are displayed in the same color. The distance between the 2 circles shows the degree of the relationship; B: Overlay map of keyword occurrence over time for papers published on the field of transplantation from the United States. The red color represents the key words that have been discussed more frequently.

Figure 5

Network visualization of the most common keyword after restricting the search to organs transplanted name. Larger circles indicate that the keyword appears more frequently. Keywords included in the same cluster are displayed in the same color. The distance between the 2 circles shows the degree of the relationship.