We shouldn’t use date of birth because the current guidance to create Observation Period from EHR data says use the first event from the data. And unless you have pediatric data, the dob is before the EHRs were used. Using the date of the last visit record might be most accurate since race/ethnicity is usually recorded at every visit and updated accordingly. But we should discuss race & ethnicity conventions after April Olympians. There are many considerations to debate.