We located RCTs published in 2009 by computerized search of PubMed, focusing on the areas of general internal medicine, oncology, cardiology, infectious disease, and obstetrics and gynecology. We analyzed the same nine journals as in 2004 based on both their impact factor in 2003, a rating of the frequency with which articles are cited in a given year determined by Journal Citation Reports® retrieved from the ISI Web of Knowledge®, and by the number of RCTs published in 2004. The 2008 impact factors have increased for each of the nine journals. The journals evaluated were New England Journal of Medicine, Journal of the American Medical Association, Annals of Internal Medicine, American Journal of Medicine, Journal of Clinical Oncology, Circulation, Clinical Infectious Disease, Obstetrics and Gynecology, and the American Journal of Obstetrics and Gynecology.
A PubMed search in each journal used limits as indexed by the National Library of Medicine to select all articles described as “randomized controlled trial” that were in English, based on data from humans, and published during 2009. In cases where an article was published online and also in print, the date of publication used for selection refers to the earlier of the two dates.
For each article, we determined the source of funding and the date when study recruitment began. Letters, Brief Communications, and clinical trials begun before 1994, as well as studies with no federal support, were excluded. Studies were also excluded when an individual was not the unit of randomization or analysis, where only a subset of a trial's subjects were analyzed, where data were combined from several trials, or where no subjects resided in the United States.
For the analysis of sex-based reporting, studies published in obstetrics and gynecology journals and those that were specific to only males or females were excluded. Conditions that are not exclusive to one sex but may disproportionately affect members of one sex (e.g., autoimmune diseases) were not excluded. Studies based in treatment facilities for veterans were not excluded unless they addressed a condition found only in men (e.g., prostate cancer). We evaluated articles for the reporting of sex-specific and race/ethnicity-specific results. Obstetrics and gynecology articles were evaluated for race/ethnicity-specific results only. We also recorded whether sex and race/ethnicity were considered during the analysis of outcomes and whether the authors acknowledged the potential impact of sex, race, or ethnicity on either the results or their generalizability.
The sample distribution across sex and race/ethnicity was recorded in terms of both percent distribution and absolute numbers (because sample size drives the ability to find statistical significance). Comparisons between subsets of the articles were made using Fisher exact test. Each article was examined in its entirety, including abstract, text, and tables. In addition to the articles themselves, any published follow-up articles or comments by either the author(s) or another researcher were examined for information relating to sex, race, and ethnicity. The race/ethnicity portion of the analysis is limited to black and Hispanic subgroup reporting, as other racial/ethnic minorities were rarely and inconsistently reported.
We were also interested in whether nonfederally funded studies were more or less compliant with NIH guidelines. To select a sample of nonfederally funded studies, we assigned random numbers generated using Microsoft Excel to the 356 studies that did not acknowledge any federal funding. We then sorted the list and selected the first 25 studies for analysis. If a study was determined to be ineligible (e.g., no subjects resided in the United States, only a portion of trial subjects' data were analyzed), that study was not included, and the next study on the list was selected.