Elsevier

American Heart Journal

Volume 158, Issue 4, October 2009, Pages 592-598.e1
American Heart Journal

Clinical Investigation
Interventional Cardiology
Patterns of use of thienopyridine therapy after percutaneous coronary interventions with drug-eluting stents and bare-metal stents

https://doi.org/10.1016/j.ahj.2009.06.030Get rights and content

Background

Twelve months of uninterrupted thienopyridine therapy after drug-eluting stents (DES) implantation was recently recommended, but limited data are available regarding long-term use in clinical practice. The objective of the study was to determine the adherence to thienopyridine therapy after stent implantation, factors associated with suboptimal adherence, and association of suboptimal adherence with mortality.

Methods

We evaluated 5,263 older patients (>65 years) who received DES and 6,081 older patients who received bare-metal stents (BMS) from December 1, 2003, to March 31, 2006, in Ontario, Canada, who were eligible to receive 12 months of thienopyridine at minimal cost.

Results

Primary nonadherence was observed among 6.9% in the DES group and 7.1% in the BMS group that did not fill a single prescription of thienopyridine within 1 year of stent implantation. Premature discontinuation occurred in a progressive manner, with 28% in the DES group and 34% in the BMS group discontinuing therapy by 6 months. Low-income patients eligible for a waiver of deductible and dispensing fee were almost 70% more likely to fill their first prescription. For DES patients, primary nonadherence (hazard ratio [HR] 2.68, 95% CI 1.77-4.07), 12-months proportional days covered <80% (HR 2.39, 95% CI 1.67-3.43), and prematurely discontinuing therapy within 6 months (HR 2.64, 95% 1.60-4.35) were associated with an increased risk of death.

Conclusions

We found suboptimal patterns of adherence to thienopyridine therapy after DES implantation that was strongly associated with an increased mortality risk. Eliminating any costs for thienopyridine therapy may be an effective strategy to increase medication adherence.

Section snippets

Data sources

The Cardiac Care Network of Ontario (CCNO) collects a prospective clinical registry of all patients undergoing cardiac invasive procedures in Ontario.15, 16 Clinical nurse coordinators at each cardiac center gather information on demographics, clinical characteristics, and relevant comorbid conditions. Details on PCI procedures were added in 2003.15, 16

The Ontario Drug Benefit prescription claims database was used to determine thienopyridine use (clopidogrel and ticlopidine) after PCI

Baseline characteristics

After exclusion criteria were applied, our cohort included 5,263 patients who received DES and 6,081 patients who received BMS. Among patients who received DES, the mean age was 73 years, 61.7% were male, and 35.6% had an acute myocardial infarction within the past month (Table I). Annual deductible and dispensing fees were waived for 19.4% of patients who had a low personal or household income (Table I).

Many demographic and clinical characteristics were observed at similar proportions among

Discussion

The availability of a population-based PCI cohort with complete prescription medication data afforded an opportunity to gain new insights into the pattern of use of thienopyridine after PCI. Despite strong recommendation from practice guidelines to take thienopyridine therapy in an uninterrupted fashion for 12 months, we found that 6.9% of patients never filled a single prescription after hospital discharge, 1 in 5 patients had suboptimal adherence, and >1 in 4 patients discontinued

Disclosures

Funding/Support: Dr Ko is supported by a Clinician-Scientist award from the Heart and Stroke Foundation of Ontario (HSFO) and a New Investigator award by CIHR. Dr Austin is supported by a Career Investigator Award by the HSFO. Dr Tu is supported by a Canada Research Chair in Health Services Research and a Career Investigator Award from the HSFO. The Institute for Clinical Evaluative Sciences is funded by an annual grant from the Ontario MOHLTC. The CCNO is funded by the MOHLTC.

Acknowledgements

We acknowledge that the data used in this publication are from the CCNO and its member hospitals. The CCNO serves as an advisory body to the Ministry of Health and Long-Term Care (MOHLTC) and is dedicated to improving the quality, efficiency, access, and equity of adult cardiovascular services in Ontario, Canada. We would like to acknowledge the support from the Ontario Health Technology Advisory Committee and the Medical Advisory Secretariat, and funding from the MOHLTC to the Programs for

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