Primary Endpoint
The main pre-specified outcome a clinical trial is designed to measure.
A primary endpoint is the main outcome a clinical trial is designed, powered, and pre-specified to measure, the result that determines whether the trial counts as a success. It's set before the trial starts, not chosen afterward based on what looked good in the data. A trial can show a notable result on a secondary endpoint, but that result carries far less regulatory and statistical weight than the primary one.
This distinction matters directly for what a promotional claim is allowed to say. A claim built on a primary endpoint the trial actually met is on solid ground. A claim built on a secondary or post-hoc finding needs much more careful framing, often a qualifier, because the trial wasn't designed to prove that result. It's exactly the kind of distinction claim-to-reference checking exists to catch before an asset ever reaches MLR.