The more publication, the higher impact factor: citation analysis of top nine gastroenterology and hepatology journals.

Background: The impact factor (IF), as the most important criterion for journal's quality measurement, is affected by the self-citation and number of publications in each journal.

Objectives: To find out the relationship between the number of publications and self-citations in a journal, and their correlations with IF.

Materials And Methods: Self-citations and impact factors of nine top gastroenterology and hepatology journals were assessed during the seven recent years (2005-2011) through Journal Citation Reports (JCR, ISI Thomson Reuters).

Results: Although impact factors of all journals increased during the study, five out of nine journals increased the number of publications from 2005 to 2011. There was an increase in self-citation only in the journal of HEPATOLOGY (499 in 2005 vs. 707 in 2011). Impact factors of journals (6.5 ± 3.5) were positively correlated with total number of publications (248.6 ± 91.7) (R: 0.688, P < 0.001). Besides, the self-citation rate (238.73 ± 195.317) was highly correlated with total number of publications in each journal (248.6 ± 91.7) (R: 0.861, P < 0.001). On the other hand, impact factor without self-citation (6.08 ± 3.3) had a correlation (R: 0.672, P < 0.001) with the number of published items (248.6 ± 91.7).

Conclusions: The number of articles and self-citation have definite effects on IF of a journal and because IF is the most prominent criterion for journal's quality measurement, it would be a good idea to consider factors affecting on IF such as self-citation.