@georgetakei I appreciate the sentiment behind this but we must be careful not to misrepresent data for our own ends.
Knowing nothing of either I can only imagine circumstances such as mood going in, attitude towards the surgery (attitude in general?), hopes/expectations (met or dashed), age of patient, success rates, expected outcome, complications, pain (ongoing? chronic?), quality of life both before and after surgery, when patient is surveyed, etc could all affect/skew one's level of regret.