NEW YORK—The answer in short is: A LOT. Thanks to a January 2015 study by Harris Poll for, the "2015 State of the Connected Patient" report, which found that U.S. 18- to 34-year-olds wanted to use various digital methods throughout the health care experience.

From managing their appointments online before even walking in the office door to having the doctor use mobile devices during the exam to quickly share heath care information to health and fitness tracking via wearables, Millennials want healthcare providers that are as just as savvy as them.

Click through to see more data from the report from eMarketer.