Bibliometrics of NIHR HTA monographs and their related journal articles

OBJECTIVES: A bibliometric analysis of the UK National Institute for Health Research (NIHR) Health Technology Assessment (HTA) monographs and their related journal articles by: (1) exploring the differences in citations to the HTA monographs in Google Scholar (GS), Scopus and Web of Science (WoS), and (2) comparing Scopus citations to the monographs with their related journal articles. SETTING: A study of 111 HTA monographs published in 2010 and 2011, and their external journal articles. MAIN OUTCOME MEASURES: Citations to the monographs in GS, Scopus and WoS, and to their external journal articles in Scopus. RESULTS: The number of citations varied among the three databases, with GS having the highest and WoS the lowest; however, the citation-based rankings among the databases were highly correlated. Overall, 56% of monographs had a related publication, with the highest proportion for primary research (76%) and lowest for evidence syntheses (43%). There was a large variation in how the monographs were cited, compared to journal articles, resulting in more frequent problems, with unlinked citations in Scopus and WoS. When comparing differences in the number of citations between monograph publications with their related journal articles from the same project, we found that monographs received more citations than their journal articles for evidence syntheses and methodology projects; by contrast, journal articles related to primary research monographs were more highly cited than their monograph. CONCLUSIONS: The numbers of citations to the HTA monographs differed considerably between the databases, but were highly correlated. When a HTA monograph had a journal article from the same study, there were more citations to the journal article for primary research, but more to the monographs for evidence syntheses. Citations to the related journal articles were more reliably recorded than citations to the HTA monographs.