Publication trends in noninvasive cardiovascular imaging: 1991-2011: a retrospective observational study.

The last twenty years have seen an explosive growth in cardiovascular disease research. The purpose of our study was to evaluate the characteristics of published research in the field of non-invasive cardiovascular imaging research from 1991-2011. Our aims were to determine: (1) the origin of the studies (international or from the U.S.) (2) differences in funding sources for U.S. publications and (3) if there has been an evolving trend pertaining to the mode of imaging. We evaluated characteristics of original research articles from Circulation, Circulation cardiovascular imaging, Journal of the American College of Cardiology (JACC), Journal of the American College of Cardiology cardiovascular imaging, Journal of the American Medical Association and the New England Journal of Medicine for the years 1991-91, 2001-02 and 2010-11. To establish trends for contributions for U.S. based studies and proportions of U.S. based studies receiving NIH funding in the study period, data was compared using a chi-square test. A two sided p value of less than or equal to 0.05 was used as the threshold for significance. Differences in modes of imaging under study were made by comparing average number of publications between the data sets in the study period using a t-test analysis. A total of 5431 studies were reviewed; 594 studies were selected as per the standardized abstraction criteria. U.S. based publications outnumbered international publications; its' share declined from 77% in 1991-92 to 57% in 2010-2011 (p<0.0001). Funding for U.S. publications by the National Institutes of Health (NIH) remained static (1991-92: 40%; 2001-02: 49%; 2010-11: 42%). A decline was seen in the investigation of echocardiography (47%, p=0.44); cardiac computed tomography and cardiac magnetic resonance imaging studies grew 6.5 times (p=0.002) and 7-fold (p=0.01) respectively. Nuclear cardiology imaging fell by more than 50% (p=0.02). The last twenty years have seen a globalization of research in non-invasive cardiovascular imaging with a shift in focus towards investigation of cardiac magnetic resonance imaging. The decline in U.S. based publications coupled with a stasis in NIH funding may call for increased federal support for non-invasive imaging research.