My mother had been taking coumadin for 5 months to treat a dvt and Pulminary Embolism (massive one) and her doctor decided to switch her to xeralto due to fluctuating INR on coumadin. She was started on 15 mg twice per day for 2 weeks then was to transition to 20mg once per day. Due to an unrelated issue, we had to get her to doctor quickly and she saw a different doctor. He flipped out and said she should never have been on 15 mg twice per day and switched her to 15mg once per day and said she would never go to 20 mg dose. Stay on 15mg. Says he knows that is the correct dose because he is the doctor and she is 82 years old and that is why. I see nothing about 15mg dose once per day for DVT and PE in elderly. Coumadin I could tell if it was working due to INR - with Xeralto I can not tell. What is the correct dose?? He is the kind of doctor who appears to write off the elderly - especially those with dementia so I am worried.