WOONSOCKET, R.I. — More than half of patients under age 45 who are prescribed medication for high cholesterol are not taking it as directed, according to a study by CVS Caremark Corp.

The company said Thursday research data show that 58% of adults ages 18 to 34 are not taking their cholesterol-lowering medications as prescribed.

The study examined data for more than 74,000 adult patients from the CVS Caremark Health Management Claims Database who incurred claims for a cholesterol-lowering medication between January 1 and December 31, 2008. Among the results, the study found that only 42% of patients ages 18 to 34 and just 50% of patients ages 35 to 44 were optimally adherent to their high-cholesterol medication.

Adherence was gauged by the medication possession ratio (MPR), a standard statistic used to measure medication adherence via pharmacy claims, CVS Caremark said. Patients with an MPR greater than or equal to 80% were deemed optimally adherent to therapy.

"This data illustrates that younger adults with high cholesterol are not taking their medication as prescribed, putting them at increased risk for developing heart disease, worsening their long-term clinical outcomes and ultimately increasing the cost of their care," Troy Brennan, executive vice president and chief medical officer at CVS Caremark, said in a statement.

"CVS Caremark engages plan participants with chronic diseases, such as high cholesterol, by addressing barriers to evidence-based care," Brennan stated. "We engage patients in their care early in the process by providing disease and therapy education and help them improve medication adherence through proactive intervention and outreach."

The company said one way it helps promote patient adherence to cholesterol-lowering and other medications is through its Adherence to Care initiative. The mail- and retail-based program provides timely interventions that include face-to-face, first-fill counseling; IVR and Web refill reminders, renewals and pickup prompts; and personalized letters to patients who have stopped filling a maintenance prescription as well as to their health care providers.

According to CVS Caremark, the program has been shown to help boost adherence to high-cholesterol therapies, with participants under age 45 experiencing an MPR increase of more than 9%.

The company noted that September is National Cholesterol Education Month and that, according to the National Institutes of Health’s National Heart, Lung and Blood Institute, high cholesterol affects more than 65 million Americans.