Rationale and objectives: To determine different countries' trend of contribution to clinical radiology journals and its relationship with impact factor.
Materials and methods: All the journals, which publish articles on clinical radiology, were selected from the category of Radiology and Nuclear Medicine group of journals, and articles published in these journals between 1991 and 2000 were searched for the authors' affiliation using the Medline database. Then, share of research output of the top-ranking 20 countries was determined along with the trend over time. Also, the relationship of different countries' contribution with the impact factor of journals was examined by cross-sectional time-series linear model.
Results: Of total articles (38,359), the United States' share for the selected journals in clinical radiology was 43.2% (16,582 articles) and ranked top in the world, followed by the United Kingdom (9.9%) and Japan (8.0%). The recent increase in the share was statistically significant for Japan, France, Germany, Italy, South Korea, Turkey, Spain, Switzerland, Austria, and China. On the other hand, the United States, United Kingdom, and Canada showed a significant negative trend. Among the top-ranking 10 countries, the US contribution was significantly higher to journals with high-impact factors, whereas the opposite was true for France.
Conclusion: The United States, United Kingdom, and Canada showed a negative trend over the last decade in terms of proportion of contribution of articles to the clinical radiology journals. However, only the United States published more articles in high-impact factor journals.