American Heart Journal
Volume 146, Issue 2 , Pages 207-209, August 2003

Is geography destiny? Illuminating the survival advantage of elderly patients in New England after acute myocardial infarction

  • John Z. Ayanian, MD, MPP

      Affiliations

    • Division of General Medicine, Department of Medicine, Brigham and Women’s Hospital and Department of Health Care Policy, Harvard Medical School, Boston, Mass, USA
    • Corresponding Author InformationReprint requests: John Z. Ayanian, MD, MPP, Department of Health Care Policy, Harvard Medical School, 180 Longwood Ave, Boston, MA 02115, USA.

Article Outline

 

Regional differences in the use of health care services are pervasive in the United States. In the Medicare program, geographic variations are clearly evident despite standardized basic benefits for elderly Americans.1, 2, 3 With the development of evidence-based clinical guidelines over the past decade, interest has grown in assessing regional differences in the treatment and outcomes of important conditions such as acute myocardial infarction.4, 5, 6

Distinctive regional patterns of care have been demonstrated, for example, in US patients enrolled in the Global Utilization of Stretokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO)-1 trial.4 In this cohort of relatively young patients who were all eligible for thrombolytic therapy, patients in New England were more likely to receive β-blockers, nitrates, and angiotensin-converting enzyme (ACE) inhibitors than patients in other regions. In contrast, coronary angiography was used much less often and more selectively for patients with recurrent ischemia in New England than in other regions. In these patients with reasonably good prognoses, the 30-day mortality rate was relatively low (approximately 7%) and did not differ significantly across regions.

In this issue of the American Heart Journal, Krumholz and colleagues assess the treatment and risk-standardized 30-day mortality rate of 167,000 elderly patients who were Medicare beneficiaries and were hospitalized for acute myocardial infarction during 1994 through 1996 in the 9 US Census regions.7 Extending prior analyses of this population,8, 9 their study found much greater use of β-blockers in New England than in other regions, both for “ideal” candidates (72% vs 42% to 60%) with no contraindications and “non-ideal” candidates (42% vs 24% to 33%) with potential contraindications to the use of β-blockers, such as congestive heart failure or pulmonary disease. Ideal candidates for aspirin use were slightly more likely to receive it in New England, but the 10% of patients who were ideal candidates for acute reperfusion therapy were slightly less likely to receive this treatment in New England than in other regions.

The most striking new finding of this study is the significantly lower risk-standardized 30-day mortality rate in New England relative to other regions (15.3% vs 17.9% to 21.7%) among elderly patients who were hospitalized for myocardial infarction. The mortality rate was especially low in 5 of the 6 states in this region, ranging from 13.5% to 15.8%. Even the highest state mortality rate in New England (17.7% in Maine) was lower than the average mortality rate in each of the other 8 US regions. The Mid-Atlantic region adjacent to New England had the second lowest risk-standardized mortality rate (17.9%) of the 9 regions studied and the second highest rates of β-blocker use for ideal (60%) and non-ideal candidates (33%). Adjusting for numerous characteristics of regions, hospitals, and patients, including the use of β-blockers and aspirin, patients in New England remained significantly less likely to die within 30 days than patients in each of the 8 other regions.

These substantial regional differences in mortality raise important policy questions about the underlying reasons for divergent outcomes. Is the quality of cardiac care inherently better in New England than in the West South Central region (Arkansas, Louisiana, Oklahoma, Texas), for example, which has the highest risk-standardized mortality rate of 21.7%? Do other factors that are unrelated to quality of care contribute to regional differences in mortality? Would regional outcomes be enhanced by concentrated efforts to increase the use of β-blockers or to improve other aspects of care?10

Krumholz et al controlled for numerous clinical variables that were strongly associated with mortality after myocardial infarction. Most of these variables differed only slightly by region and were thus unlikely to explain regional differences in mortality rate. They adjusted for regional characteristics, including the median household income of patients’ communities and the distance from patients’ homes to their hospitals, that may influence patient outcomes regardless of the care they received.11, 12 The investigators also controlled for 2 hospital characteristics associated with better quality of care: the number of patients treated at each hospital13 and admission to a teaching hospital.14 These hospital characteristics may have contributed to New England’s lower mortality rate, because New England ranked third and second on these 2 measures, respectively, among the 9 regions.

Two specific processes of care, the use of aspirin and of β-blockers, were included as potential mediators in the adjusted analyses of 30-day mortality rates. Although regional differences in aspirin use were probably too small to explain corresponding differences in mortality, Krumholz and colleagues estimated that the substantially greater use of β-blockers in New England may have explained as much as one quarter of the overall reduction in 30-day mortality rate as compared with other regions. This estimate is plausible on the basis of randomized15 and observational9 studies of the early use of β-blockers for patients with myocardial infarction. Nonetheless, controlling for all of these factors reduced the unadjusted odds ratio for mortality in each region compared with New England by only 10% to 25%, leaving 75% to 90% of the regional mortality rate difference unexplained.

What other factors may have contributed to the lower 30-day mortality rate of patients in New England? Some of these regional differences could be related to residual confounding by clinical or demographic factors that were unmeasured or variably ascertained. Despite relatively similar rates of impaired ventricular function, heart failure was recorded more commonly in New England than in other regions, which may have influenced risk-standardized mortality rates. Even with perfect adjustment for clinical risk factors, however, the regional survival advantage of patients treated in New England would likely persist.

Further insights would arise from determining how quality of care differs between New England and other regions before, during, and after hospitalization. Such assessments could help to improve the outcomes of Medicare beneficiaries in all regions. The use of effective cardiovascular drugs before admission could be readily assessed from hospital records or pharmacy databases. Patients who are taking β-blockers before admission may have lower adjusted mortality rate when hospitalized for this condition,16 and the use of β-blockers in the ambulatory care of hypertension or angina is probably more common in New England than other regions, as it is after acute myocardial infarction. The use of aspirin, ACE inhibitors, or cholesterol-lowering drugs before admission for myocardial infarction may also have beneficial effects on the subsequent mortality rate, but regional differences in the use of these therapies are less clear.17, 18

Evaluations of hospital care should focus on regional comparisons of the appropriateness of coronary angiography and revascularization procedures19, 20 and their associated complication rates. In the study by Krumholz et al, the New England and Mid-Atlantic regions had markedly lower rates of revascularization procedures than other regions (7% and 10% vs 15% to 25%). Regional rates of these procedures were highly correlated with their availability at hospitals in each region, and both variables were inversely correlated with 30-day mortality rates at the regional level. Although the short-term risks of revascularization procedures may mask some corresponding longer-term benefits, it is doubtful that regional differences in short-term mortality rates would be reversed with longer periods of observation.5 Patients in the New England and Mid-Atlantic regions, therefore, may be exposed less frequently to the risks of coronary revascularization procedures when the potential benefits are limited. Furthermore, greater proportions of revascularization procedures in these Northeastern regions may be performed in high-volume hospitals, thereby reducing complication rates and contributing to better outcomes.21, 22

Finally, although the quality of care after hospital discharge may not be a major determinant of regional differences in 30-day mortality rates, this domain is important to consider when evaluating longer-term outcomes. Because patients remain at substantial risk of recurrent myocardial infarction, congestive heart failure, and premature death, the types of physicians, drugs, and procedures they use after discharge may yield clinically important differences in survival.17, 23 Understanding regional differences in ambulatory care could foster better strategies for optimizing the outcomes of patients who survive a myocardial infarction, with the recognition that this acute event provides a critical but narrow opportunity to improve the care of patients with chronic cardiovascular disease.

Back to Article Outline

References 

  1. Chassin MR, Brook RH, Park RE, et al.  Variations in the use of medical and surgical services by the Medicare population. N Engl J Med. 1986;314:285–290
  2. Welch WP, Miller ME, Welch HG, et al.  Geographic variation in expenditures for physicians’ services in the United States. N Engl J Med. 1993;328:621–627
  3. In:  Wennberg JE,  Cooper MM editor. The Dartmouth atlas of health care 1999 (the quality of medical care in the United States: a report on the Medicare program). Dartmouth: American Hospital Publishing; 1999;
  4. Pilote L, Califf RM, Sapp S, et al.  Regional variation across the United States in the management of acute myocardial infarction. N Engl J Med. 1995;333:565–572
  5. Guadagnoli E, Hauptman PJ, Ayanian JZ, et al.  Variation in the use of cardiac procedures after acute myocardial infarction. N Engl J Med. 1995;333:573–578
  6. O’Connor GT, Quinton HB, Traven ND, et al.  Geographic variation in the treatment of acute myocardial infarction. The Cooperative Cardiovascular Project. JAMA. 1999;281:627–633
  7. Krumholz HM, Chen J, Rathore SS, et al. Regional variation in the treatment and outcomes of myocardial infarction: investigating New England’s advantage. Am Heart J 2003;146:242–9
  8. Krumholz HM, Radford MJ, Chen J, et al.  National use and effectiveness of β-blockers for the treatment of elderly patients after acute myocardial infarction. National Cooperative Cardiovascular Project. JAMA. 1998;280:623–629
  9. Krumholz HM, Radford MJ, Wang Y, et al.  Early β-blocker therapy for acute myocardial infarction in elderly patients. Ann Intern Med. 1999;131:648–654
  10. Soumerai SB, McLaughlin TJ, Gurwitz JH, et al.  Effect of local medical opinion leaders on quality of care for acute myocardial infarction (a randomized controlled trial). JAMA. 1998;279:1358–1363
  11. Alter DA, Naylor CD, Austin P, et al.  Effects of socioeconomic status on access to invasive cardiac procedures and on mortality after acute myocardial infarction. N Engl J Med. 1999;341:1359–1367
  12. Piette JD, Moos RH. The influence of distance on ambulatory care use, death, and readmission following a myocardial infarction. Health Serv Res. 1996;31:573–591
  13. Thiemann DR, Coresh J, Oetgen WJ, et al.  The association between hospital volume and survival after acute myocardial infarction in elderly patients. N Engl J Med. 1999;340:1640–1648
  14. Allison JJ, Kiefe CI, Weissman NW, et al.  Relationship of hospital teaching status with quality of care and mortality for Medicare patients with acute MI. JAMA. 2000;284:1256–1262
  15. First International Study of Infarct Survival Collaborative Group. Randomised trial of intravenous atenolol among 16,027 cases of suspected acute myocardial infarction (ISIS-1). Lancet. 1986;2:57–66
  16. Nidorf SM, Parsons RW, Thompson PL, et al.  Reduced risk of death at 28 days in patients taking a β blocker before admission to hospital with myocardial infarction. BMJ. 1990;300:71–74
  17. Seddon ME, Ayanian JZ, Landrum MB, et al.  Quality of ambulatory care after myocardial infarction among Medicare patients by type of insurance and region. Am J Med. 2001;111:24–32
  18. Ayanian JZ, Landrum MB, McNeil BJ. Use of cholesterol-lowering therapy by elderly adults after myocardial infarction. Arch Intern Med. 2002;162:1013–1019
  19. Guadagnoli E, Landrum MB, Normand S-L, et al.  Impact of underuse, overuse, and discretionary use on geographic variation in the use of coronary angiography following myocardial infarction. Med Care. 2001;39:446–458
  20. Garg PP, Landrum MB, Normand SL, et al.  Understanding individual and small area variation in the underuse of coronary angiography following acute myocardial infarction. Med Care. 2002;40:614–626
  21. Jollis JG, Peterson ED, DeLong ER, et al.  The relation between the volume of coronary angioplasty procedures at hospitals treating Medicare beneficiaries and short-term mortality. N Engl J Med. 1994;331:1625–1629
  22. Grumbach K, Anderson GM, Luft HS, et al.  Regionalization of cardiac surgery in the United States and Canada (geographic access, choice, and outcomes). JAMA. 1995;274:1282–1288
  23. Ayanian JZ, Landrum MB, Guadagnoli E, et al.  Specialty of ambulatory care physicians and mortality among elderly patients after myocardial infarction. New Eng J Med. 2002;347:1678–1686

PII: S0002-8703(03)00238-2

doi:10.1016/S0002-8703(03)00238-2

American Heart Journal
Volume 146, Issue 2 , Pages 207-209, August 2003

Article Tools