About 16 percent of patients prescribed the anticoagulant clopidogrel after having a drug-coated stent inserted don't get the prescription filled immediately after being discharged from the hospital.

These patients have nearly double the risk of myocardial infarction or death compared to similar patients who fill their clopidogrel prescription the day they're discharged.

At hospital discharge, one in six patients who have a drug-coated stent inserted do not immediately fill a blood thinner prescription, increasing their risk for subsequent myocardial infarction and death, researchers report in Circulation: Cardiovascular Quality and Outcomes.

To reduce the risk of restenosis following stent placement, doctors prescribe anticoagulants, such as clopidogrel, following the procedure and when patients are discharged from the hospital, said P. Michael Ho, M.D., Ph.D., the study's lead author.

"A surprising number of patients delayed filling the prescription," said Ho, who is also staff cardiologist at the Denver Veterans Administration Medical Center and associate professor of medicine at the University of Colorado in Denver. "We expected their physicians and the healthcare system to be more vigilant in making sure they got their medications."

Ho and his fellow researchers examined records from 7,402 patients from 2004-2007 who were able to obtain prescription drugs at reduced costs through their health plans. These patients had not been prescribed clopidogrel in the three months before their stent procedure.

Researchers found that 16.3 percent of patients (1,210) waited at least a day to fill the blood-thinner prescription, and of those, 2.2 percent (165) never filled their prescription. The median delay was three days.

Over about 22 months of follow-up, patients who had any delay in filling the prescription had a 14.2 percent risk of heart attack or death - almost double the 7.9 percent risk of those who filled their prescription the day of discharge from the hospital.

"When cardiac patients are discharged from the hospital, they are prescribed a lot of medications and may not remember the importance of all of them, specifically clopidogrel," said Ho, who also is an affiliate investigator with the Institute for Health Research, Kaiser Permanente of Colorado. "In addition, the doctors in the hospital may not know who is providing their patients follow-up care and often there is a gap in the transfer of information from inpatient to outpatient settings. We need to improve this transition period from hospital to home and make sure patients understand the importance of their medications."

Patients who didn't immediately fill their prescription were older and more likely to have other health conditions that required additional prescriptions, researchers found. Those who delayed filling the first prescription also delayed getting subsequent refills of clopidogrel.

To increase the number of patients who fill their medications in a timely manner and take the medication as prescribed, Ho suggests that patients receive a follow-up call soon after discharge from a pharmacist or nurse. The caller would review the patients' medications to make sure they know when to take them and for how long.

"Each hospital should review its discharge process to understand if there are potential gaps, and if there are gaps, design interventions to improve this transition period," Ho said.

The study was funded by a grant to The HMO Research Network Center for Education and Research on Therapeutics (CERTs) from the Agency for Healthcare Research and Quality (AHRQ). The Effective Health Care Cardiovascular Consortium by DEcIDE (Developing Evidence to Inform Decisions about Effectiveness) contributed to the development of the stent database used in the study.

Co-authors are Thomas T. Tsai, M.D., M.Sc.; Thomas M. Maddox, M.D., M.Sc.; J. David Powers, M.S.; Nikki M. Carroll, M.S.; Cynthia Jackevicius, Pharm.D., M.Sc.; Alan S. Go, M.D.; Karen L. Margolis, M.D., M.P.H.; Terese A. DeFor, M.S.; John S. Rumsfeld, M.D., Ph.D.; David J. Magid, M.D., M.P.H. Author disclosures are on the manuscript.