PHP177 - Characterization of Observational Phase IV Studies Submitted to Clinicaltrials.Gov Between 2007 and 2017

Abstract

Phase IV studies are conducted after a drug or therapy has been approved and is on the market and include experimental (interventional) trials and observational (non-interventional) studies (NIS). In an observational study, investigators observe subjects and measure variables of interest without assigning treatments to the subjects. These studies are essential to explore outcomes as part of routine medical care in the real world. We aimed to characterize observational Phase IV studies completed between 2007 and 2017 in the US. We searched the ClinicalTrials.gov website on 05-Jan-18 using following search terms: observational studies, completed, Phase IV, United States, 01-Jan-2007 to 31-Dec-2017. 98 studies were identified (53% commercial, 40% academic and 7% Investigator-initiated trials). 56% are NIS, 39% are interventional trials, and 5% could not be classified. A third of studies include a comparator arm. Around 50% are drug studies, followed by 16% device, and 8% vaccine. In terms of design, 67% are cohort studies, 14% are case series and 13% are case-control studies. Approximately 70% collect longitudinal and 30% cross-sectional data. Approximately 85% collect prospective and 15% retrospective data (e.g. databases). Based on top-line study information provided, 62% of studies collect effectiveness outcomes, 36% cohort characteristics, 26% safety, 22% PROs, and 31% other outcomes (e.g. lab values). The search engine did not allow determining if studies were requested by a regulator. Most studies that were yielded by our search strategy are NIS focusing on drug/vaccine and with a prospective cohort single-group design. Approximately 40% of studies were classified as interventional phase IV trials. This could be due to an incompatibility within the ClinicalTrials.gov search algorithm as observational phase IV studies should mainly be NIS, and will be further researched.