Doctors are reporting an exciting win for gene testing and personalized medicine. Checking patients' DNA before starting them on the blood thinner warfarin helps get the dose right and avoid complications.

About 2 million Americans start on warfarin each year to prevent blood clots after surgery or for other medical conditions. The right dose can vary widely. Gene tests can guide how much someone needs.

A study found that people given gene testing had a 30 percent lower risk of being hospitalized in their first six months on the drug compared to other patients whose dose was set by trial and error.

Results were reported Tuesday at an American College of Cardiology meeting in Atlanta.