Pharmacy & Therapeutics - May 2008 - (Page 295) Effect of Persistence with Drug Therapy on Myocardial Re-infarction continued from page 290 DISCUSSION Our primary finding was that persistence in the use of initial AMI-preventive medication, taken after a first AMI, was a significant predictor of re-infarction risk. Our results were consistent with those from the Rasmussen study.6 Those authors, examining the relationship between drug adherence and all-cause mortality in elderly AMI survivors, found a 0.25fold and a 0.12-fold increased hazard ratio of deaths when comparing a low-adherent group with high-adherent and intermediate-adherent groups, respectively. Our study yielded a non-persistence rate of 57.7% among patients who were prescribed AMI-preventive medications within one month after the initial diagnosis. This rate was higher than the findings from a study in The Netherlands, which suggested a one-year discontinuation rate of 32%.14 However, considering our study population (mostly African-Americans, relatively young, and of lower social economic status), the difference was not surprising. Patients who had a concurrent diagnosis of heart disease, hyperlipidemia, or renal disease were at higher risk of having another MI event. Those results were consistent with those of other studies.6,15 For example, in a prospective cohort study of 374 patients 33 to 88 years of age (mean age, 62 years) with a history of MI, Wong et al. found that those with elevated cholesterol levels had an increased risk for re-infarction, death from coronary disease, and death overall.16 The positive relationship between renal disease and a risk of re-infarction has been well documented; even milder degrees of renal impairment increase the composite endpoint of death from re-infarction and other cardiovascular causes.15 REFERENCES 1. Antman EM, Anbe DT, Armstrong PW, et al. ACC/AHA guidelines for the management of patients with ST-elevation myo cardial infarction—executive summary: A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 1999 Guidelines for the Management of Patients With Acute Myocardial Infarction). Circulation 2004;110:588–636. 2. American Heart Association. Heart disease and stroke statistics, 2004 update. Dallas, Tex. 3. van de Werf F, Ardissino D, Betriu A, et al. Management of acute myocardial infarction in patients presenting with ST-segment elevation: The Task Force of the Management of Acute Myocardial Infarction of the European Society of Cardiology. Eur Heart J 2003;(24):28–66. 4. Braunwald E, Antman EM, Beasley JW, et al. ACC/AHA guidelines for the management of patients with unstable angina and non-ST-segment elevation myocardial infarction: A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on the Management of Patients With Unstable Angina). J Am Coll Cardiol 2000;36:970–1062. 5. McCormick D, Gurwitz JH, Lessard D, et al. Use of aspirin, betablockers, and lipid-lowering medications before recurrent acute myocardial infarction: Missed opportunities for prevention? Arch Intern Med 1999;159(6):561–567. 6. Rasmussen JN, Chong A, Alter DA. Relationship between adherence to evidence-based pharmacotherapy and long-term mortality after acute myocardial infarction. JAMA 2007;297:177–186. 7. Khot UN, Khot MB, Bajzer CT, et al. Prevalence of conventional risk factors in patients with coronary heart disease. JAMA 2003; 290:898–904. 8. Pearson TA, Laurora I, Chu H, et al. The lipid treatment assessment project (L-TAP): A multicenter survey to evaluate the percentages of dyslipidemic patients receiving lipid-lowering therapy and achieving low-density lipoprotein cholesterol goals. Arch Intern Med 2000;160:459–467. 9. Stamler J, Stamler R, Neaton JD, et al. Low risk-factor profile and long-term cardiovascular and noncardiovascular mortality and life expectancy: Findings for five large cohorts of young adult and middle-aged men and women. JAMA 1999;282:2012–2018. 10. Kaiser Commission on Medicaid and the Uninsured. Medicaid Prescription Drug Spending and Use. Washington, DC: Henry J. Kaiser Foundations; 2004. 11. Shaya FT, El Khoury AC, Mullins CD, et al. Drug therapy persistence and stroke recurrence. Am J Manag Care 2006;12:313–319. 12. Brener SJ, Ellis SG, Sapp SK, et al. Predictors of death and reinfarction at 30 days after primary angioplasty: The GUSTO IIb and RAPPORT Trials. Am Heart J 2000;139(3):476–481. 13. De Luca G, Ernst N, van’t Hof AWJ, et al. Predictors and clinical implications of early reinfarction after primary angioplasty for ST-segment elevation myocardial infarction. Am Heart J 2006;151: 1256–1259. 14. van der Elst ME, Bouvy ML, de Blaev CJ, et al. Preventive drug use in patients with a history of nonfatal myocardial infarction during 12-year follow-up in The Netherlands: A retrospective analysis. Clin Ther 2005;27(11):1806–1814. 15. Anavekar NS, McMurray JJV, Velazquez EJ, et al. Relation between renal dysfunction and cardiovascular outcomes after myocardial infarction. N Engl J Med 2004;351:1285–1295. 16. Wong ND, Wilson PWF, Kannel WB. Serum cholesterol as a prognostic factor after myocardial infarction: The Framingham study. Ann Intern Med 1991;115:687–693. I STUDY LIMITATIONS As a result of the demographic characteristics of the Medicaid population and Medicaid administrative claims data (primarily for billing purposes), our study had several limitations. First, although our database included a large study population, we were unable to control for some clinical indicators (e.g., electrocardiographic and biochemical indexes), because these were not recorded in the Medicaid data. Nevertherless, the evidence-based results should be valuable in policymaking and in interventions designed for vulnerable populations. Another major limitation relates to the study’s generalizability. Our results might not be analogous to those of the average population in the U.S. because our patients were predominantly female, younger, and African-American. Although we used three months as a washout period to maximize our chance of selecting incident AMI patients, some subjects might have had an AMI more than three months before their first diagnosis was recorded in our database. Finally, our data might not have captured all patient care information, such as lifestyle factors and the use of over-thecounter drugs. CONCLUSION The persistent use of initial AMI-preventive medication significantly reduced the risk of MI recurrence. Heart disease, renal disease, and hyperlipidemia increased the likelihood of a re-infarction. Vol. 33 No. 5 • May 2008 • P&T® 295
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