IMPORTANCE Results from high-profile randomized controlled trials (RCTs) are routinely reported through press release months prior to peer-reviewed publication. There are potential benefits to press releases (e.g., knowledge dissemination, ensuring regulatory compliance), but also potential drawbacks (e.g., selective reporting, positive "spin").

OBJECTIVE:

To characterize the practice of press release predating the publication of a drug-related RCT in a peer-reviewed journal ("preemptive press release"), including factors associated with this practice. DESIGN, SETTING, AND

PARTICIPANTS:

We systematically reviewed all RCTs of medications published between 2015 and 2019 in the New England Journal of Medicine (NEJM), Journal of the American Medical Association (JAMA), and Lancet. Press releases were identified using a systematic search of the grey literature (e.g., press release databases, study sponsor websites). An RCT was considered to have a preemptive press release if the press release was published at least three months (90 days) prior to the date of publication in a peer-reviewed journal. MAIN OUTCOMES AND

MEASURES:

Presence of preemptive press release, defined as a press-release at least 90 days prior to the date of publication in a peer-reviewed journal. As secondary measures for dissemination, we also assessed citation count and Altmetric score.

RESULTS:

We identified 988 RCTs, of which 172 (17%) had a press release published at least 90 days before the date of peer-reviewed publication. Press releases were published a median of 246 days (interquartile range [IQR] 169-366 days) before publication in a peer-reviewed journal. In the multivariable logistic regression model, the strongest predictor of having a preemptive press release was funding by a pharmaceutical company (odds ratio 13, 95% CI 7, 25). Approximately 85% of RCTs with preemptive press releases had a positive primary outcome and, concordantly, 81% of the corresponding press releases had a positive headline. Multivariable regression models identified studies with a preemptive press release had a similar Altmetric score (median - 15, 95% CI - 33, 12) and higher median citation count (median 22 [95% CI 10 to 33] compared to studies without a preemptive press release. CONCLUSIONS AND RELEVANCE Preemptive press releases were common, most often issued for trials funded by a pharmaceutical company, and typically preceded publication in a peer-reviewed journal by approximately eight months.