The [assessment model](https://github.com/cbmi/varify/blob/6e57f46b6baf157111e6a8b4bb95ea35c3466e2c/varify/assessments/models.py#L55) also needs to be updated as it has a foreign key reference into Result as well. I have not checked the code but any other models with Result foreign keys will need to be updated as well.