I think you’re spot-on for the issues of percentage change (PCHG) and I haven’t found a valid reason for using it as a primary endpoint.
It might be helpful by demonstrating with your trial data or other publicly available data to show why PCHG won’t work as mentioned in below post:
- ie, check model performance (adjusted R-squared values) for an ANCOVA model using the following endpoints 1) PCHG, 2) a natural log transformed endpoint, 3) raw data. You might find that approaches 2 and 3 would give reasonable R-squared values and approach 1 would be close to 0.