Durham, NC - Long-term adherence to secondary-prevention therapies for coronary artery disease remains poor, a new study has shown [1]. Reporting their findings online January 9, 2006 in Circulation, Dr L Kristin Newby (Duke Clinical Research Institute, Durham, NC) and colleagues say considerable attention must be focused on understanding and improving long-term compliance to achieve better clinical outcomes.

Dr L Kristin Newby (Source: Duke University Medical Center)

Nearly half the CAD patients in the seven-year study admitted they don't consistently take beta blockers, lipid-lowering therapy, and other medications, the researchers found.

"We've focused very well on in-hospital use of therapies, but this is a very controlled environment," Newby told heartwire. "When they become outpatients, it's a much more variable environment, and this highlights where our next major focus needs to be." Only a few prior studies have evaluated long-term use of therapies, she adds.

In an accompanying editorial [2], Dr Sidney C Smith Jr (Center for Cardiovascular Science and Medicine, University of North Carolina, Chapel Hill) says the report by Newby et al "is of particular interest because it provides information on the use of medical therapies over time and examines consistency of use long term and its relationship to mortality."

The researchers used the Duke Databank for Cardiovascular Disease to analyze medication adherence among 31 750 patients who had undergone a cardiac procedure at Duke, had at least one coronary artery more than 50% blocked, or had coronary artery bypass surgery. All patients reported their use of aspirin, beta blockers, and lipid-lowering drugs in annual surveys between 1995 and 2002.
    

Patients had to have at least two consecutive surveys returned during the study. Consistent use was defined as reporting use of medications on at least two successive occasions and continuing to report use through the end of the study period. ACE-inhibitor use was also recorded for patients with and without heart failure. The researchers found the use of all drugs and combinations increased year to year.

Among patients who had not experienced heart failure, 39% reported using ACE inhibitors in 2002; however, consistent use was only 20%. Among patients who had experienced heart failure, ACE inhibitor use was 51% in 2002 and consistent use was 39%.

Consistent use of any of the therapies was associated with higher survival rates (compared with never users). Specifically, those who were consistent in their use of aspirin saw a 42% reduction in risk of death, while beta-blocker use led to a 37% reduction and lipid-lowering therapy a 48% reduction. Patients who took aspirin plus beta blockers had a 39% reduction while those taking all three had a 33% reduction in mortality. Heart-failure patients consistently taking ACE inhibitors had a 25% reduction in mortality, but no association was found among patients who used ACE inhibitors but had not experienced heart failure.

Newby et al say their findings in more than 30 000 patients across multiple categories of evidence-based medications and a seven-year period of observation extend those of previous studies.

"Despite marked increases in the yearly prevalence of use in our study population from 1995 to 2003, consistent use lagged substantially behind, suggesting that in addition to the importance of prescribing, additional factors are important in determining long-term adherence," they write.

The researchers also found that, paradoxically, consistent use of evidence-based medicines was lower among groups with the highest risk of poor outcomes, who would therefore benefit most from sustained therapy. Older patients, those with heart failure, smokers, and diabetics were least likely to consistently take medication.

"These findings suggest that it may be possible to design educational and compliance intervention programs targeted to groups of patients at high risk for both underuse of medications in secondary prevention and adverse clinical outcomes."

They also observed that for each agent studied, the strongest factor associated with consistent use was baseline use of other evidence-based medicines. "This most likely reflects characteristics involved in both physician prescription of evidence-based medicines in general and patient compliance with a program of therapy."

Newby told heartwirethat to tackle this problem "will require a multipronged approach. Long-term adherence programs need to involve the patient, their families, pharmacies, outpatient clinicians and nurses, and other mid-level healthcare providers."

She believes cardiologists are interested in compliance in their patients, "but once we finish a procedure and discharge, it does become difficult to have an impact. We need better communication with primary-care providers," she concludes.