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Relating quality of care to clinical outcomes in heart failure: In search of the missing link
Journal of Cardiac Failure Vol. 7 No. 4 2001
Editorial Comment
Relating Quality of Care to Clinical Outcomes in Heart Failure: In Search of the Missing Link MARVIN A. KONSTAM, MD Boston, Massachusetts
As heart failure becomes an increasingly important public health problem in the aging population, all avenues continue to be sought toward improving clinical outcomes among patients with this condition. From the perspective of clinical care, this process most appropriately begins with the demonstration of a significant treatment effect within a randomized clinical trial. Drawing upon such information, uniform guidance must be provided to the practitioner, defining a consensus view of optimal quality of care. Such guidance, in the form of clinical practice guidelines, has reached beyond the realm of randomized clinical trial evidence, drawing from multiple sources of information, often with weak or absent documentation of linkage between the clinical process being advocated and the outcome being sought. Polanczyk et al (1) in this issue of the Journal of Cardiac Failure provide some of this linkage by examining correlation between indices of quality of care for patients hospitalized with heart failure and the important clinical outcome of hospital readmission. Krumholz et al (2) recently reviewed quality measures in heart failure. They reported characteristics of guideline recommendations that are most appropriately translated into measures to judge the quality of care delivery, including 1) strong process-outcome linkage, 2) wide applicability to a well-defined patient population, and 3) amenability to measurement based on existing or readily adapted documentation standards. At present, few recommendations meet these rigorous requirements. The Centers for Medicare and Medicaid Services (previously the Health Care Finance Administration) in an effort to
improve quality of care in heart failure have adapted 2 measures that come close to meeting these standards: measurement of left ventricular function and prescription of angiotensin-converting enzyme (ACE) inhibitors. In contrast, Polanczyk et al explored an instrument based on a wide variety of quality measures for inhospital management, including criteria for 1) admission work-up, 2) evaluation and treatment during hospitalization, and 3) readiness for discharge. They correlated scores on the various components of this instrument with the likelihood of rehospitalization for heart failure during 3 months of follow-up in 200 patients discharged alive after index hospitalization for heart failure. Using a multivariate model that included both clinical characteristics and quality criteria, the investigators observed that a low score for evaluation and treatment independently predicted readmission. Patients meeting ⱕ50% of the evaluation and treatment criteria were 2.5 times more likely to be readmitted for heart failure than the remaining population. The frequency of 1) performing any diagnostic evaluation, 2) performing echocardiography in patients with an unknown ejection fraction, and 3) treatment with an ACE inhibitor differed significantly between patient groups with and without readmission. Although the precise mechanism for linkage between the diagnostic evaluation, including echocardiography, and readmission is uncertain, these findings bring us a step closer to documenting that improvement in clinical practice, based on established quality standards, yields improved clinical outcomes in patients with heart failure. Readmission after a hospitalization for heart failure is common, estimated as 44% at 6 months within the Medicare population (3). Reduction in heart failure hospitalizations is an appropriate goal for treatment modalities and quality improvement strategies because hospitalization impacts adversely on both sides of the cost-effectiveness equation. On the cost side, hospitalization is the principal component of the high cost of care for patients with heart failure, representing 70% to 75%
From the Division of Cardiology, Department of Medicine, New England Medical Center and Tufts University School of Medicine, Boston, MA. Reprint requests: Marvin A. Konstam, MD, Hospital Box 108, New England Medical Center, 750 Washington St, Boston, MA 02111. Copyright © 2001 by Churchill Livingstone威 1071-9164/01/0704-0004$35.00/0 doi:10.1054/jcaf.2001.30132
299
300 Journal of Cardiac Failure Vol. 7 No. 4 December 2001 of total direct costs (4–8), a finding we have recently confirmed by analysis of Medicare claims in eastern Massachusetts. On the effectiveness side, hospitalization can be assumed to represent either a failure of treatment and/or progression of disease severity and detracts from the patient’s overall quality of life. As pharmacologic treatments continue to whittle down mortality rates in heart failure, reduction of hospitalization frequency emerges as an increasingly important therapeutic goal. ACE inhibitors (9), -blockers (10–13), and most recently the angiotensin-receptor blocker valsartan (14) have been shown to reduce heart failure hospitalizations. In the practice setting, physician adherence to prescription recommendations and patient compliance represent important goals in efforts to improve clinical outcomes, including reduction in heart failure hospitalizations. We (15) and others (16–21) have found disease management strategies, focusing on patient compliance and nurse responsiveness to clinical change, to reduce heart failure hospitalization rates. In our randomized-controlled study (15), we found significant reductions in heart failure hospitalizations and hospital days during a 3-month period of nurse-driven intervention, although withdrawal of the active intervention resulted in loss of the initial benefit. Although randomized, controlled trials provide the strongest evidence in support of the impact of a treatment or a strategy on hospitalizations, observational studies such as that of Polanczyk et al can yield key insights into the linkages between health care processes and hospitalizations rates within a population and a treatment environment that is more representative of the real world. Patient populations in most randomized heart failure trials have predominantly consisted of male patients with low left ventricular ejection fractions and mean age in the low 60s (22). In contrast, the patient population examined by Polanczyk et al was more typical (23), with 48% women, mean age of 72 years, and 30% of patients with normal left ventricular ejection fraction. Most of the information that we have on typical patient populations in “real world” practice has come from such observational investigation. Polanczyk et al confirm the role of ACE inhibitors in reducing subsequent hospitalization rates. The significance of performing diagnostic tests, including echocardiography, in preventing readmission is less certain. The observational nature of the investigation leaves open the possibility that these actions identified patients less likely to be hospitalized, rather than directly impacting on outcomes. For example, the performance of more diagnostic tests may represent a marker for patients who are viewed by their physicians to have a better prognosis. The investigators strove to exclude such possibilities by demonstrating significant independent predictive power within a multivariate analysis incorporating a battery of
clinical characteristics. Nevertheless, it remains possible that this analysis did not correct for clinical differences, which were not accounted for by the objective measures analyzed. Polanczyk et al also observed that participation of a cardiologist in the care of the patient correlated with higher quality of care scores. These findings are consistent with those of Edep et al (24) who surveyed various types of physicians and found cardiologists to be more aware of clinical trial results and to more commonly practice in accordance with guideline recommendations than less specialized physicians. Polanczyk et al were not able to identify cardiologist involvement as an independent predictor of improved outcome. However, in the case of measures with well-documented processoutcome links, larger and longer-term investigation is likely to demonstrate that physicians who use such processes achieve improved clinical outcomes in their patients. Such results should drive consideration of broader involvement of specialists in the care of patients with heart failure, and/or more aggressive educational and other quality-improving measures directed toward generalists, who primarily manage most patients with heart failure. A recent report of quality improvement efforts in various cardiovascular disorders, including heart failure, yielded the disappointing finding of numerous obstacles precluding adequate documentation and tracking of quality measures across a broad patient population (25). As studies such as that of Polanczyk et al continue to fill in the gaps of our knowledge regarding the linkage between the processes of care for patients with heart failure and key outcomes such as readmission, it will be imperative to improve our ability to track these processes. In so doing, we must continue to focus on those select care measures for which clear process-outcome linkage has been established. Beyond deriving data from randomized clinical trials and beyond establishing consensus recommendations, techniques designed to advance adherence to such well-established processes represent an important step toward improving overall outcomes for patients with heart failure.
References 1. Polanczyk CA, Newton C, Dec GW, Di Salvo TG: Quality of care and hospital readmission in congestive heart failure: an explicit review process. J Card Fail 2001;7: 289–298 2. Krumholz HM, Baker DW, Ashton CM, Dunbar SB, Friesinger GC, Havranek EP, Hlatky MA, Konstam, MA, Ordin DL, Pina I, Pitt B, Spertus JA: Evaluating quality of care for patients with heart failure. Circulation 2000;101:e122–e140
Linking Quality to Outcomes 3. Krumholz HM, Parent EM, Tu N, Vaccarino V, Wang Y, Radford MJ, Hennen J: Readmission after hospitalization for congestive heart failure among Medicare beneficiaries. Arch Intern Med 1997;157:99–104 4. American Heart Association. 2001 heart and stroke statistical update. American Heart Association, Dallas, TX 2000, p. 31 5. Andrews R, Cowley AJ: Clinical and economic factors in the treatment of congestive heart failure. Pharmacoeconomics 1995;7119–7127 6. Agency for Health Care Policy and Research. National inpatient sample. Washington DC, release 5, 1996 data, PB 99-500480, 1999 7. Konstam MA, Kimmelstiel CD: Economics of heart failure. In: Balady GJ, Pina IL, eds. Exercise and heart failure. Armonk, NY, Futura, 1997 pp. 19–28 8. Gregory D, Udelson JE, Konstam MA: Economic impact of beta blockade in heart failure. Am J Med 2000;109: 1S–6S 9. The SOLVD Investigators: Effect of enalapril on survival in patients with reduced left ventricular ejection fractions and congestive heart failure. N Engl J Med 1991;325: 293–302 10. Packer M, Bristow MR, Cohn JN, Colucci WS, Fowler MB, Gilbert EM, Shusterman NH: The effect of carvedilol on morbidity and mortality in patients with chronic heart failure. N Engl J Med 1996;334:1349–1355 11. Hjalmarson A, Goldstein S, Fagerberg B, Wedel H, Waagstein F, Kjekshus J, et al: Effects of controlledrelease metoprolol on total mortality, hospitalizations, and well-being in patients with heart failure: the Metoprolol CR/XL Randomized Intervention Trial in Congestive Heart Failure (MERIT-HF). JAMA 2000;283:1295–1302 12. CIBIS-II Investigators and Committees: The Cardiac Insufficiency Bisoprolol Study II (CIBIS-II): a randomized trial. Lancet 1999;353:9–13 13. Packer M, Coats AJS, Fowler MB, Katus HA, Krum H, Mohasci P, et al: Effect of carvedilol on survival in severe chronic heart failure. N Engl J Med 2001;344:1651–1658 14. Tognoni G, Cohn JN: A randomized trial of the angiotensin receptor valsartan in chronic heart failure. New Engl J Med (in press) 15. Kimmelstiel CD, Levine D, Perry K, Patel A, Sadaniantz A, Gorham N, Cunnie P, Duggan L, Cotter L, LaBresh K, Brill D, Rand W, Udelson J, Lorell B, Konstam MA:
16.
17.
18.
19
20.
21.
22.
23.
24.
25.
O Konstam 301
Randomized, controlled evaluation of short- and longterm benefits of heart failure disease management within a diverse provider network: the SPAN-CHF Trial (abstr). J Am Coll Cardiol 2001;37:219A Rich MW, Beckham V, Wittenberg C, Leven CL, Freedland KE, Carney RM: A multidisciplinary intervention to prevent the readmission of elderly patients with congestive heart failure. N Engl J Med 1995;333:1190–1195 West JA, Miller NH, Parker KM, Livingston NA, Steimle AE, Hamilton MA, et al: A comprehensive management system for heart failure improves clinical outcomes and reduces medical resource utilization. Am J Cardiol 1997; 79:58–63 Fonarow GC, Stevenson LW, Walden JA, Senneca D, Chandour G, Clark M, et al: Impact of a comprehensive heart failure management program on hospital readmission and functional status of patients with advanced heart failure. J Am Coll Cardiol 1997;30:725–732 Hanumanthu S, Butler J, Chomsky D, Davis S, Wilson JR: Effect of a heart-failure program on hospitalization frequency and exercise tolerance. Circulation 1997;96: 2842–2848 Stewart S, Pearson S, Horowitz JD: Effects of a homebased intervention among patients with congestive heart failure discharged from acute hospital care. Arch Intern Med 1998;158:1067–1072 Serxner S, Miyaji M, Jeffords J: Congestive heart-failure disease-management study: a patient education intervention. Congestive Heart Fail 1998;4:23–28 Konstam MA: Progress in heart failure management? Lessons from the real world. Circulation 2000;102:1076– 1078 MacIntyre K, Capewell S, Stewart S, Chalmers JW, Boyd J, Finlayson A, Redpath A, Pell JP, McMurray JJ. Evidence of improving prognosis in heart failure: trends in case fatality in 66 547 patients hospitalized between 1986 and 1995. Circulation 2000;102:1126–1131 Edep ME, Shah NB, Tateo IM, Massie BM: Differences between primary care physicians and cardiologist in management of congestive heart failure: relation to practice guidelines. J Am Coll Cardiol 1997;30:518–526 Di Salvo TG, Normand SLT, Hamptman PJ, Guadagnoli E, Palmer RH, McNeil BJ: Pitfalls in assessing the quality of care for patients with cardiovascular disease. Am J Med 2001;111:297–303
Editorial Comment
Relating Quality of Care to Clinical Outcomes in Heart Failure: In Search of the Missing Link MARVIN A. KONSTAM, MD Boston, Massachusetts
As heart failure becomes an increasingly important public health problem in the aging population, all avenues continue to be sought toward improving clinical outcomes among patients with this condition. From the perspective of clinical care, this process most appropriately begins with the demonstration of a significant treatment effect within a randomized clinical trial. Drawing upon such information, uniform guidance must be provided to the practitioner, defining a consensus view of optimal quality of care. Such guidance, in the form of clinical practice guidelines, has reached beyond the realm of randomized clinical trial evidence, drawing from multiple sources of information, often with weak or absent documentation of linkage between the clinical process being advocated and the outcome being sought. Polanczyk et al (1) in this issue of the Journal of Cardiac Failure provide some of this linkage by examining correlation between indices of quality of care for patients hospitalized with heart failure and the important clinical outcome of hospital readmission. Krumholz et al (2) recently reviewed quality measures in heart failure. They reported characteristics of guideline recommendations that are most appropriately translated into measures to judge the quality of care delivery, including 1) strong process-outcome linkage, 2) wide applicability to a well-defined patient population, and 3) amenability to measurement based on existing or readily adapted documentation standards. At present, few recommendations meet these rigorous requirements. The Centers for Medicare and Medicaid Services (previously the Health Care Finance Administration) in an effort to
improve quality of care in heart failure have adapted 2 measures that come close to meeting these standards: measurement of left ventricular function and prescription of angiotensin-converting enzyme (ACE) inhibitors. In contrast, Polanczyk et al explored an instrument based on a wide variety of quality measures for inhospital management, including criteria for 1) admission work-up, 2) evaluation and treatment during hospitalization, and 3) readiness for discharge. They correlated scores on the various components of this instrument with the likelihood of rehospitalization for heart failure during 3 months of follow-up in 200 patients discharged alive after index hospitalization for heart failure. Using a multivariate model that included both clinical characteristics and quality criteria, the investigators observed that a low score for evaluation and treatment independently predicted readmission. Patients meeting ⱕ50% of the evaluation and treatment criteria were 2.5 times more likely to be readmitted for heart failure than the remaining population. The frequency of 1) performing any diagnostic evaluation, 2) performing echocardiography in patients with an unknown ejection fraction, and 3) treatment with an ACE inhibitor differed significantly between patient groups with and without readmission. Although the precise mechanism for linkage between the diagnostic evaluation, including echocardiography, and readmission is uncertain, these findings bring us a step closer to documenting that improvement in clinical practice, based on established quality standards, yields improved clinical outcomes in patients with heart failure. Readmission after a hospitalization for heart failure is common, estimated as 44% at 6 months within the Medicare population (3). Reduction in heart failure hospitalizations is an appropriate goal for treatment modalities and quality improvement strategies because hospitalization impacts adversely on both sides of the cost-effectiveness equation. On the cost side, hospitalization is the principal component of the high cost of care for patients with heart failure, representing 70% to 75%
From the Division of Cardiology, Department of Medicine, New England Medical Center and Tufts University School of Medicine, Boston, MA. Reprint requests: Marvin A. Konstam, MD, Hospital Box 108, New England Medical Center, 750 Washington St, Boston, MA 02111. Copyright © 2001 by Churchill Livingstone威 1071-9164/01/0704-0004$35.00/0 doi:10.1054/jcaf.2001.30132
299
300 Journal of Cardiac Failure Vol. 7 No. 4 December 2001 of total direct costs (4–8), a finding we have recently confirmed by analysis of Medicare claims in eastern Massachusetts. On the effectiveness side, hospitalization can be assumed to represent either a failure of treatment and/or progression of disease severity and detracts from the patient’s overall quality of life. As pharmacologic treatments continue to whittle down mortality rates in heart failure, reduction of hospitalization frequency emerges as an increasingly important therapeutic goal. ACE inhibitors (9), -blockers (10–13), and most recently the angiotensin-receptor blocker valsartan (14) have been shown to reduce heart failure hospitalizations. In the practice setting, physician adherence to prescription recommendations and patient compliance represent important goals in efforts to improve clinical outcomes, including reduction in heart failure hospitalizations. We (15) and others (16–21) have found disease management strategies, focusing on patient compliance and nurse responsiveness to clinical change, to reduce heart failure hospitalization rates. In our randomized-controlled study (15), we found significant reductions in heart failure hospitalizations and hospital days during a 3-month period of nurse-driven intervention, although withdrawal of the active intervention resulted in loss of the initial benefit. Although randomized, controlled trials provide the strongest evidence in support of the impact of a treatment or a strategy on hospitalizations, observational studies such as that of Polanczyk et al can yield key insights into the linkages between health care processes and hospitalizations rates within a population and a treatment environment that is more representative of the real world. Patient populations in most randomized heart failure trials have predominantly consisted of male patients with low left ventricular ejection fractions and mean age in the low 60s (22). In contrast, the patient population examined by Polanczyk et al was more typical (23), with 48% women, mean age of 72 years, and 30% of patients with normal left ventricular ejection fraction. Most of the information that we have on typical patient populations in “real world” practice has come from such observational investigation. Polanczyk et al confirm the role of ACE inhibitors in reducing subsequent hospitalization rates. The significance of performing diagnostic tests, including echocardiography, in preventing readmission is less certain. The observational nature of the investigation leaves open the possibility that these actions identified patients less likely to be hospitalized, rather than directly impacting on outcomes. For example, the performance of more diagnostic tests may represent a marker for patients who are viewed by their physicians to have a better prognosis. The investigators strove to exclude such possibilities by demonstrating significant independent predictive power within a multivariate analysis incorporating a battery of
clinical characteristics. Nevertheless, it remains possible that this analysis did not correct for clinical differences, which were not accounted for by the objective measures analyzed. Polanczyk et al also observed that participation of a cardiologist in the care of the patient correlated with higher quality of care scores. These findings are consistent with those of Edep et al (24) who surveyed various types of physicians and found cardiologists to be more aware of clinical trial results and to more commonly practice in accordance with guideline recommendations than less specialized physicians. Polanczyk et al were not able to identify cardiologist involvement as an independent predictor of improved outcome. However, in the case of measures with well-documented processoutcome links, larger and longer-term investigation is likely to demonstrate that physicians who use such processes achieve improved clinical outcomes in their patients. Such results should drive consideration of broader involvement of specialists in the care of patients with heart failure, and/or more aggressive educational and other quality-improving measures directed toward generalists, who primarily manage most patients with heart failure. A recent report of quality improvement efforts in various cardiovascular disorders, including heart failure, yielded the disappointing finding of numerous obstacles precluding adequate documentation and tracking of quality measures across a broad patient population (25). As studies such as that of Polanczyk et al continue to fill in the gaps of our knowledge regarding the linkage between the processes of care for patients with heart failure and key outcomes such as readmission, it will be imperative to improve our ability to track these processes. In so doing, we must continue to focus on those select care measures for which clear process-outcome linkage has been established. Beyond deriving data from randomized clinical trials and beyond establishing consensus recommendations, techniques designed to advance adherence to such well-established processes represent an important step toward improving overall outcomes for patients with heart failure.
References 1. Polanczyk CA, Newton C, Dec GW, Di Salvo TG: Quality of care and hospital readmission in congestive heart failure: an explicit review process. J Card Fail 2001;7: 289–298 2. Krumholz HM, Baker DW, Ashton CM, Dunbar SB, Friesinger GC, Havranek EP, Hlatky MA, Konstam, MA, Ordin DL, Pina I, Pitt B, Spertus JA: Evaluating quality of care for patients with heart failure. Circulation 2000;101:e122–e140
Linking Quality to Outcomes 3. Krumholz HM, Parent EM, Tu N, Vaccarino V, Wang Y, Radford MJ, Hennen J: Readmission after hospitalization for congestive heart failure among Medicare beneficiaries. Arch Intern Med 1997;157:99–104 4. American Heart Association. 2001 heart and stroke statistical update. American Heart Association, Dallas, TX 2000, p. 31 5. Andrews R, Cowley AJ: Clinical and economic factors in the treatment of congestive heart failure. Pharmacoeconomics 1995;7119–7127 6. Agency for Health Care Policy and Research. National inpatient sample. Washington DC, release 5, 1996 data, PB 99-500480, 1999 7. Konstam MA, Kimmelstiel CD: Economics of heart failure. In: Balady GJ, Pina IL, eds. Exercise and heart failure. Armonk, NY, Futura, 1997 pp. 19–28 8. Gregory D, Udelson JE, Konstam MA: Economic impact of beta blockade in heart failure. Am J Med 2000;109: 1S–6S 9. The SOLVD Investigators: Effect of enalapril on survival in patients with reduced left ventricular ejection fractions and congestive heart failure. N Engl J Med 1991;325: 293–302 10. Packer M, Bristow MR, Cohn JN, Colucci WS, Fowler MB, Gilbert EM, Shusterman NH: The effect of carvedilol on morbidity and mortality in patients with chronic heart failure. N Engl J Med 1996;334:1349–1355 11. Hjalmarson A, Goldstein S, Fagerberg B, Wedel H, Waagstein F, Kjekshus J, et al: Effects of controlledrelease metoprolol on total mortality, hospitalizations, and well-being in patients with heart failure: the Metoprolol CR/XL Randomized Intervention Trial in Congestive Heart Failure (MERIT-HF). JAMA 2000;283:1295–1302 12. CIBIS-II Investigators and Committees: The Cardiac Insufficiency Bisoprolol Study II (CIBIS-II): a randomized trial. Lancet 1999;353:9–13 13. Packer M, Coats AJS, Fowler MB, Katus HA, Krum H, Mohasci P, et al: Effect of carvedilol on survival in severe chronic heart failure. N Engl J Med 2001;344:1651–1658 14. Tognoni G, Cohn JN: A randomized trial of the angiotensin receptor valsartan in chronic heart failure. New Engl J Med (in press) 15. Kimmelstiel CD, Levine D, Perry K, Patel A, Sadaniantz A, Gorham N, Cunnie P, Duggan L, Cotter L, LaBresh K, Brill D, Rand W, Udelson J, Lorell B, Konstam MA:
16.
17.
18.
19
20.
21.
22.
23.
24.
25.
O Konstam 301
Randomized, controlled evaluation of short- and longterm benefits of heart failure disease management within a diverse provider network: the SPAN-CHF Trial (abstr). J Am Coll Cardiol 2001;37:219A Rich MW, Beckham V, Wittenberg C, Leven CL, Freedland KE, Carney RM: A multidisciplinary intervention to prevent the readmission of elderly patients with congestive heart failure. N Engl J Med 1995;333:1190–1195 West JA, Miller NH, Parker KM, Livingston NA, Steimle AE, Hamilton MA, et al: A comprehensive management system for heart failure improves clinical outcomes and reduces medical resource utilization. Am J Cardiol 1997; 79:58–63 Fonarow GC, Stevenson LW, Walden JA, Senneca D, Chandour G, Clark M, et al: Impact of a comprehensive heart failure management program on hospital readmission and functional status of patients with advanced heart failure. J Am Coll Cardiol 1997;30:725–732 Hanumanthu S, Butler J, Chomsky D, Davis S, Wilson JR: Effect of a heart-failure program on hospitalization frequency and exercise tolerance. Circulation 1997;96: 2842–2848 Stewart S, Pearson S, Horowitz JD: Effects of a homebased intervention among patients with congestive heart failure discharged from acute hospital care. Arch Intern Med 1998;158:1067–1072 Serxner S, Miyaji M, Jeffords J: Congestive heart-failure disease-management study: a patient education intervention. Congestive Heart Fail 1998;4:23–28 Konstam MA: Progress in heart failure management? Lessons from the real world. Circulation 2000;102:1076– 1078 MacIntyre K, Capewell S, Stewart S, Chalmers JW, Boyd J, Finlayson A, Redpath A, Pell JP, McMurray JJ. Evidence of improving prognosis in heart failure: trends in case fatality in 66 547 patients hospitalized between 1986 and 1995. Circulation 2000;102:1126–1131 Edep ME, Shah NB, Tateo IM, Massie BM: Differences between primary care physicians and cardiologist in management of congestive heart failure: relation to practice guidelines. J Am Coll Cardiol 1997;30:518–526 Di Salvo TG, Normand SLT, Hamptman PJ, Guadagnoli E, Palmer RH, McNeil BJ: Pitfalls in assessing the quality of care for patients with cardiovascular disease. Am J Med 2001;111:297–303