In 2007, a reported 4.2 million Americans purchased 27.9 million anticoagulant prescriptions, totaling $905.2 million, according to a survey published by the Agency for Healthcare Research and Quality (AHRQ).

The report found about 10 percent of Americans 75 and older and 6 percent of Americans between the ages of 65 and 74 used one or more blood thinners in 2007. In contrast, less than 1 percent of people younger than 65 used a blood thinner.

Of those who took anticoagulants, 74 percent had cardiac conditions, 40.3 percent underwent surgery, 30.2 percent were diagnosed with cancer and 27.6 percent had diabetes.

One-quarter of patients prescribed the drugs showed signs of dysrhythmia and a range of 4 to 6 percent of patients prescribed anticoagulants had hypertension or high cholesterol.

The survey found that per adult the average annual expenditure of anticoagulant drug purchases was $213.16, with an average annual out-of-pocket cost of $91.37.

Of the total prescriptions, 19.3 percent were generics with an average expenditure and mean out-of-pocket cost per per perscription of $18.17 and $7.30, respectively. Of the total prescriptions, 8.5 million were brand-name drugs with an average expenditure and mean out-of-pocket cost per perscription of $64.96 and $28.95, respectively.

AHRQ, part of the U.S. Department of Health and Human Services, accumulated these data from the Medical Expenditure Panel Survey.