Quantification of Authors' Contributions and Eligibility for Authorship: A Randomized Trial

Objective: To quantify authors' contributions in manuscripts sent to the Croatian Medical Journal and their eligibility for authorship criteria defined by the International Committee of Medical Journal Editors (ICMJE) by 1) substantial contributions to conception and design, or acquisition of data, or analysis and interpretation of data ; 2) drafting the article or revising it critically for important intellectual content ; and 3) final approval of the version to be published. Design: All 532 authors who submitted 121 manuscripts to the Croatian Medical Journal from January 18 to May 23, 2005, were randomly allocated into two groups and asked to rate their contributions from 0 (none) to 4 (full). A total of 240 were assigned to the rating-questionnaire group (57 manuscripts) and 292 were assigned to the yes/no-questionnaire group (64 manuscripts) for 11 contribution categories. They were not instructed on ICMJE authorship criteria. Results: The number of manuscripts with authors not fulfilling ICMJE criteria was significantly higher in yes/no-questionnaire grup than in the rating-questionnaire group (82.8% vs 28.1% ; χ s ; 1=36.87, P< .001). The number of undeserved authors was significantly higher in yes/no-questionnaire grup than in the rating-questionnaire group (64.7% vs 13.8% ; χ s ; 1=140.77, P< .001). The rating-questionnaire group also reported more contribution categories. Conclusions: The lower prevalence of undeserved authorship in the rating-questionnaire group indicates that quantification of authors' contributions may be a more accurate method of contribution disclosure.