Reporting data dredging in a study During a statistical analysis of a study, I found an interesting relationship between two variables that was not part of the original hypothesis. It is, however, clinically interesting and I want to report it in the study.

I've never seen a medical study in which authors admitted to data dredging although I do know it's prevalent. I'm confident enough in my study and methods that I'm willing to admit to it.

What would be the best way to do so in a manuscript? Would I include all the information of the dredged variable such as p-values and confidence intervals, but put a note that this hypothesis is based on the data?
Yes. I would have a separate section of your paper entitled something like "Further exploratory analysis", report what you did and what you found, and note that until a study has been design to specifically test your hypothesis, it remains a hypothesis, but suggest that it might be an attractive target for further study.