We retrieved 746 articles, of which 623 were research articles (eg, clinical trials, case reports, meta-analyses) and 123 were commentaries, letters, and other communications that did not present original research. There were 2985 authors and 135 journals. The number of articles per author ranged from 1 to 25.
Of the 441 research articles (excluding case reports), 316 (71.7%) did not include a statement identifying the source of support for the study (including declarations of no support). These statements were more likely to appear in journals that endorsed the ICMJE guidelines (34% vs 21%; χ2
0.002) and in journals with higher impact factors (median impact factor, 3.55 vs 3.06; p
0.04). A total of 125 organizations were listed as sources of support. The top 5 sources (ie, Johnson & Johnson, Boston Scientific, CardioVascular Research Foundation [South Korea]; Ministry of Health and Welfare [South Korea]; and Guidant) accounted for 28% of the articles in which a source of support was declared.
Eight of the 623 research articles (1.3%) contained statements describing the contributions made by each author.
shows the percentages of articles in which a disclosure statement was present for all, some, or none of the authors. Overall, 116 articles (15.5%) contained a disclosure statement for all authors, and 620 articles (83.1%) did not contain a disclosure statement for any author. Articles in journals that endorsed the ICMJE guidelines were more likely than other articles to have disclosure statements for all authors (25.3% vs 7.4%). Articles in which all authors had disclosure statements were more likely to appear in journals with higher impact factors (median impact factor, 11.63 vs 3.06; p<0.001).
Articles with disclosure statements for all, some, or no authors.*
Prevalence and Nature of Disclosures
A total of 168 authors (5.6%) had a disclosure statement in at least 1 article. The combination of authors and articles resulted in 4664 author instances (ie, opportunities for disclosure). Of these author instances, 220 (4.7%) had a disclosure, 577 (12.4%) had a declaration of no interests, and 3867 (82.9%) had no disclosure statement (). Author instances in research articles were slightly less likely to have a disclosure statement than author instances in other articles. Excluding case reports did not change the percentages by more than 1 percentage point (data not shown).
The maximum number of financial interests disclosed for a single author in a single article was 4. The disclosed relationships referred to 78 organizations. The 5 most frequent organizations (ie, Johnson & Johnson, Boston Scientific, Medtronic, Sanofi-Aventis, and Bristol-Myers Squibb) accounted for 59% of the relationships. In 4 cases, instead of a specific organization, the disclosure statement described relationships with multiple unnamed organizations (eg, “all drug-eluting stent companies,” “medical device companies” ). Of the 468 relationships disclosed, the most frequent relationship types included receipt of research support (25%), speaker fees (17%), and consultancies (15%).
Consistency of Disclosures
Of the 2985 authors in the database, 683 (22.9%) authored more than 1 article and 307 (10.3%) authored 3 or more articles. For 454 of the authors with multiple articles (66.5%), each author's articles always agreed in terms of whether the articles disclosed a financial relationship, declared no relationships, or had no disclosure statement. For 86 of the authors with multiple articles (12.6%), there was no agreement among articles.
shows the results of comparing the presence or absence of disclosure statements across articles for the same author. The large percentage of comparisons that resulted in agreement (4256/5573 [76.4%]) was due almost entirely to cases in which the absence of a disclosure statement was consistent across articles for the same author (4093/4256 [96.2%]). The most frequent cases of disagreement (840/1317 [63.8%]) occurred when one article contained a declaration of no financial interests and another article by the same author contained no statement. There were 26 cases in which one article disclosed an author's financial interests and another article declared that the same author had nothing to disclose. As shown in the last column and last row of , these 26 cases involved 16 authors. Authors with industry affiliations represented a small proportion (<12%) of any type of agreement or disagreement.
As also shown in , comparisons between two articles in different journals were more likely to result in inconsistencies of disclosure than were comparisons between two articles in the same journal (30.1% vs 3.5%; χ2
<0.001). In other words, almost all of the inconsistencies (1270/1317 [96.4%]) were between articles by the same author in different journals. Comparisons between research articles and other articles were more likely to result in disagreement than were comparisons between two research articles (29.4% vs 23.0%; χ2
Among the 75 authors who disclosed a relationship with a specific organization, there were 2 cases (2.7%) in which the organization was disclosed in every article the author wrote about coronary stents in the same year.