anastrozole aromatase inhibitors blood clots breast cancer cancer risk cash based practice concierge medicine conjugated equine estrogens CVD deep venous thrombosis direct primary care DPC DVT e2 estradiol estrogen in men gynecomastia healthcare burnout medical business model medical practice model medroxyprogesterone melatonin natural hormones nurse practitioner oral estradiol oral estrogen PCSK-9 Inhibitors PE physician burnout polypharmacy practice transition premarin prevent heart disease pulmonary embolism reverse diabetes sickness medicine sleep synthetic hormones testosterone in men thyroid thyroid optimization transdermal estrogen wellness medicine whi women's health initiative