The Transparent Reporting of Evaluations with Nonrandomized Designs (TREND) guidelines were first published in 2004, in response to the perceived value and effect of the Consolidated Standards of Reporting Trials (CONSORT) guidelines that had been introduced a decade earlier.¹ The initial development of these guidelines was spearheaded by the US Centers for Disease Control and Prevention HIV/AIDS Prevention Research Synthesis team. The initial interest was specifically in standardization of the reporting of behavioral interventions in HIV/AIDS (eg, interventions to improve adherence to antiretroviral therapy or to increase frequency of partner testing), but the group broadened its interest to include all evaluations of interventions using nonrandomized designs. The guideline authors, comprising researchers, policy makers, and journal editors, developed a reporting framework that was based on the CONSORT guidelines but adapted for evaluation of interventions other than randomized trials.