WOONSOCKET, R.I. — Many patients with chronic conditions aren’t filling their prescriptions, according to a new study by CVS Caremark Corp. and Horizon Blue Cross Blue Shield of New Jersey.

CVS Caremark said Thursday that the study, published this week in the American Journal of Pharmacy Benefits, found that over 20% of patients who were prescribed asthma controllers and more than 34% of patients who were prescribed medications for high cholesterol didn’t fill their initial prescriptions.

"Most previous studies on primary nonadherence have depended upon patient self-reporting or focused on hospital populations that could be tracked more closely," Joshua Liberman, vice president of strategic research at CVS Caremark and the study’s primary author, said in a statement. "With the increasing use of e-prescribing, we can now get a more accurate picture of how many members fail to fill that first prescription and insights into factors associated with that failure."

The review by CVS Caremark looked at e-prescriptions written by 507 doctors in the Horizon Blue Cross Blue Shield of New Jersey network between January and October 2006. The intent of the study was to determine the extent and cause of primary nonadherence for people prescribed medications for high cholesterol and asthma. CVS Caremark noted that the study reviewed only e-prescriptions written for the two chronic illnesses, which it said gives a clearer indication of those not filling their initial prescription because electronic orders reach drug stores immediately and claims data show which prescriptions are picked up or not.

"By analyzing e-prescribing data, we now have a very clear picture of how many patients are not filling their prescriptions," observed Richard Popiel, vice president and chief medical officer for health insurer Horizon Blue Cross Blue Shield of New Jersey, serves over 3.6 million members. "The study shows that there needs to be more education and intervention to ensure patients understand the importance of adhering to prescribed medical protocols."

According to CVS Caremark, the study indicates that nonadherence is more prevalent than previously thought and highlights the need for more education and intervention programs to increase the likelihood of patients adhering to medication regimens prescribed by their doctors.

Medication adherence has been a key area of study for CVS Caremark, which has launched a multiyear effort to better understand why some people stop taking their prescriptions.

Last week, the company announced the results of a survey of specialty pharmacy patients, which found that nearly 70% believe their pharmacy team played a key role in encouraging them to take their medications as prescribed. And earlier this month, a CVS Caremark-commissioned study by Minds at Work revealed various psychological factors influencing medication adherence.

Other efforts include a three-year collaboration with researchers from Harvard and Brigham and Women’s Hospital to study pharmacy claims data to better understand patient behavior around medication adherence and the launch of a Behavior Change Research Partnership led by experts from Carnegie Mellon University, Dartmouth University’s Tuck School of Business and the University of Pennsylvania Medical School and The Wharton School of Business. The CVS Caremark and Harvard collaboration is also looking at adherence through the lens of e-prescribing, among other topics.