Original article
Validating recommendations for coronary angiography following acute myocardial infarction in the elderly: A matched analysis using propensity scores

https://doi.org/10.1016/S0895-4356(00)00321-8Get rights and content

Abstract

We determined whether adherence to recommendations for coronary angiography more than 12 h after symptom onset but prior to hospital discharge after acute myocardial infarction (AMI) resulted in better survival. Using propensity scores, we created a matched retrospective sample of 19,568 Medicare patients hospitalized with AMI during 1994–1995 in the United States. Twenty-nine percent, 36%, and 34% of patients were judged necessary, appropriate, or uncertain, respectively, for angiography while 60% of those judged necessary received the procedure during the hospitalization. The 3-year survival benefit was largest for patients rated necessary [mean survival difference (95% CI): 17.6% (15.1, 20.1)] and smallest for those rated uncertain [8.8% (6.8, 10.7)]. Angiography recommendations appear to select patients who are likely to benefit from the procedure and the consequent interventions. Because of the magnitude of the benefit and of the number of patients involved, steps should be taken to replicate these findings.

Introduction

The widespread and increasing use of guidelines and protocols has led researchers to investigate two questions: first, the extent to which current practices are consistent with these guidelines; and second, the extent to which adherence to guidelines leads to better outcomes for patients. Because of the importance of cardiovascular disease in terms of morbidity, mortality, and cost, many investigations have focused on this clinical condition. For example, several researchers have examined coronary angiography and revascularization procedures and demonstrated wide variability in use 1, 2, 3, 4, 5, 6 and some instances of inappropriate use 7, 8, 9, 10, 11. The correlation between adherence to treatment recommendations and outcomes has been studied less often, although one study of HMO enrollees in California [12] suggested improved survival among patients undergoing angiography who were rated necessary for the procedure.

In this study we assessed the link between adherence to recommendations for coronary angiography and survival using observational data from seven US states. Because guidelines increasingly incorporate a continuum of recommendations (e.g., the procedure is necessary, is appropriate but not necessary, is of uncertain benefit, or is inappropriate), we undertook to validate the accuracy of the explicit scale of appropriateness embedded in these guidelines. If there is no clear relationship with outcomes and the appropriateness scale, these scales should be discarded.

To achieve our goals, we studied a large national sample of Medicare beneficiaries treated after an acute myocardial infarction (AMI). We evaluated the appropriateness of coronary angiography more than 12 h after symptom onset but prior to hospital discharge and determined the extent to which use of the procedure in accordance with appropriateness ratings correlated with survival at 3 years from admission. We focused on coronary angiography because of wide variations in its use. Because our study is based on observational data, we adjusted for confounding by creating a matched sample using propensity scores.

Section snippets

Study population

We obtained our sample through the Cooperative Cardiovascular Project (CCP) [13] undertaken by the Health Care Financing Administration (HCFA). The sample included 64,140 fee-for-service Medicare beneficiaries aged 65–89 years who were discharged with a diagnosis of AMI from hospitals located in California, Florida, Massachusetts, New York, Ohio, Pennsylvania, and Texas during the period January 1, 1994 through June 30, 1995. These states were selected because they were known to differ in

Characteristics of the study population

The study cohort consisted of 37,788 patients, the majority of whom were white, slightly less than half were female, and 46% of whom underwent angiography during the initial episode of hospital care (Table 1). Twenty-nine percent, 36%, and 34% of patients were rated as necessary, appropriate but not necessary, or uncertain for angiography, respectively, in the matched cohort. Unadjusted survival at 3 years was 64% in the full cohort and 68% in the matched cohort.

The distribution of patients

Discussion

This study provides data on two important questions related to the management of patients after an AMI. First, we observed a relationship between coronary angiography and improved survival for those patients undergoing catheterization more than 12 h after symptom onset. Second, the strength of this relationship correlated with the continuum of recommendations for this procedure in the expected directions. These results are important because the patient population was a large and generalizable

Acknowledgements

The authors are indebted to Joseph P. Newhouse, Ph.D. for valuable comments; Laurie Silva, Ph.D. for project coordination; and Margaret Volya, M.Sc. and Christina Fu, Ph.D.; for expert programming assistance—all in the Harvard Medical School, Boston, MA; and two anonymous reviewers for their helpful comments. Supported by Grant RO1-HS08071 from the Agency for Health Care Policy and Research, Rockville, MD.

References (35)

  • S.J. Bernstein et al.

    The appropriateness of use of coronary angiography in New York State

    J Am Med Assoc

    (1993)
  • G.M. Anderson et al.

    Case selection and appropriateness of coronary angiography and coronary artery bypass graft surgery in British Columbia and Ontario

    Can J Cardiol

    (1997)
  • A. Bengston et al.

    The appropriateness of performing coronary angiography and coronary artery revascularization in a Swedish population

    J Am Med Assoc

    (1994)
  • J.V. Selby et al.

    Variation among hospitals in coronary angiography practices and outcomes after myocardial infarction in a large health maintenance organization

    N Engl J Med

    (1996)
  • T.A. Marciniak et al.

    Improving the quality of care for Medicare patients with acute myocardial infarctionresults from the Cooperative Cardiovascular Project

    J Am Med Assoc

    (1998)
  • J. Chen et al.

    Do “America's best hospitals” perform better for acute myocardial infarction?

    N Engl J Med

    (1999)
  • D.W. Bates et al.

    Coronary angiography and angioplasty after acute myocardial infarctiona literature review

    Ann Intern Med

    (1997)
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