|
|
||||||||||
|
J Am Coll Cardiol, 1998; 32:885-889 © 1998 by the American College of Cardiology Foundation |

a The Lancaster Heart Foundation, Lancaster, Pennsylvania, USA
* The Pennsylvania Health Care Cost Containment Council, Harrisburg, Pennsylvania, USA
Messiah College, Grantham, Pennsylvania, USA
Manuscript received December 19, 1997; revised manuscript received June 3, 1998, accepted June 12, 1998.
Address for correspondence: Dr. Paul N. Casale, The Lancaster Heart Foundation, 217 Harrisburg Avenue, Lancaster, Pennsylvania 17603
lanheart{at}redrose.net
| Abstract |
|---|
|
|
|---|
Background. There has been increasing pressure to limit access to specialists as a method to reduce the cost of health care. There is little known about the effect on outcome of this shift in the care of acutely ill patients.
Methods. We analyzed the data from 30,715 direct hospital admissions for the treatment of acute myocardial infarction in Pennsylvania in 1993. A risk-adjusted in-hospital mortality model was developed in which 12 of 20 clinical variables were significant independent predictors of in-hospital mortality. To determine whether there were factors other than patient risk that significantly influenced in-hospital mortality, multiple logistic regression analysis was performed on physician, hospital and payer variables.
Results. After adjustment for patient characteristics, a multiple logistic regression analysis identified treatment by a cardiologist (odds ratio = 0.83 [confidence interval {CI} = 0.74 to 0.94] p < 0.003) and physicians treating a high volume of acute myocardial infarction patients (odds ratio = 0.89 [CI = 0.80 to 0.99] p < 0.03) as independent predictors of lower in-hospital mortality. Treatment by a cardiologist as compared to primary care physicians was also associated with a significantly lower length of stay for both medically treated patients (p < 0.01) and those undergoing revascularization (p < 0.01).
Conclusions. Treatment by a cardiologist is associated with approximately a 17% reduction in hospital mortality in acute myocardial infarction patients. In addition, patients of physicians treating a high volume of patients have approximately an 11% reduction in mortality. This has important implications for the optimal treatment of acute myocardial infarction in the current transformation of the health care delivery system.
| ||||||||||
Previous studies have reported that cardiologists are more likely to be aware of and to use life-saving therapies for the treatment of unstable angina and AMI (6,7). A recent study by Jollis et al. (8) suggested that outcome of AMI is better in Medicare patients who are admitted to a hospital by a cardiologist than in those admitted by a primary care physician. The authors suggested that this may be in part due to the greater use by cardiologists of therapies associated with increased survival.
To determine the impact of specialty vs. primary care on in-hospital mortality in patients aged 30 to 99 years who present with an AMI, we analyzed the data from the recently published Pennsylvania Health Care Cost Containment Council report on AMI (9,10).
| Methods |
|---|
|
|
|---|
There were 510 patients excluded from the analysis, which included those under the age of 30 or over the age of 99, patients who left against medical advice, patients of clinical complexity (metastatic cancer, major trauma, anoxic encephalopathy or concurrent heart transplantation), patients involved in hospital transfers, patients of physicians who treated more than 100 patients in which it appeared that the entire groups cases were assigned to a single physician, patients treated by a specialty other than cardiology or primary care and patients treated at a hospital that closed since 1993 or at a hospital that treated less than 30 AMI patients in 1993.
Data collection. All acute care hospitals in Pennsylvania are required to abstract previously established key clinical data from all patient admissions. These data are then entered into the Atlas System (formerly known as MedisGroups) (11) from which the Atlas admission severity score is calculated. Other clinical variables are abstracted from the charts by trained hospital personnel and translated to ICD-9-CM codes.
The assignment of attending physicians was the decision of the hospital and its physicians (10). Depending on individual hospital policy, some hospitals assigned the physician who admitted the patient, others used the physician who discharged the patient and some used the physician who spent the most time with the patient. The assignment of specialty was self-reported by the individual attending physician. This physician was given the opportunity to review and verify the data submitted for analysis as well as the opportunity to change the identification of the attending physician for a given patient when appropriate.
Statistical analysis. A risk-adjusted model of in-hospital mortality was developed for the patients admitted directly to a hospital by testing 20 clinical and demographic variables, including the Atlas admission severity score which itself is a collection of 23 clinical variables. These variables include age, history of angina, history of congestive heart failure, history of stroke, elevated blood urea nitrogen, number of diseased coronary arteries, evidence of congestive heart failure by chest x-ray, elevated creatine phosphokinase, low ejection fraction, low Glasgow Coma Scale, high glucose, left ventricular hypertrophy, mechanical ventilation, AMI, myocardial infarction of indeterminate age, high pH, low pH, low partial pressure of oxygen, history of percutaneous transluminal coronary angioplasty (PTCA), increased respirations, low systolic blood pressure, high serum glutamic-oxaloacetic transaminase and high white blood cell. Multiple logistic regression analysis identified 12 additional clinical variables as significant independent predictors of in-hospital mortality: higher Atlas admission severity score, older age, presence of cardiac dysrhythmia, cardiogenic shock, cardiomyopathy, conduction disorder, diabetes, dialysis, female gender, anterior infarct site, prior coronary bypass surgery and renal failure. These were included in the model to measure risk-adjusted mortality.
Clinical variables that had not been found to be predictors of in-hospital mortality were hypertension with or without complication, heart failure, age squared, malignant neoplasm and admission type or source. The results of this model were published in 1996 by the Pennsylvania Health Care Cost Containment Council (9). The receiver operating characteristic curve area for the model was 88.1%.
To determine whether factors other than patient risk significantly influenced in-hospital mortality, physician-, hospital- and primary payer-related characteristics were entered into the model after controlling for the significant clinical variables using the same multiple logistic regression technique. The physician characteristics included physician specialty (cardiologist vs. primary care provider [internist or family practice physician]) and number of AMI patients treated by a physician. The median number of AMI patients treated by a physician was 12 and a high-volume physician was defined as one who treated more than 12 AMI patients. The number of physicians in a practice group treating AMI patients, type of practice (solo, group with 1 or group with more than 1 physician treating AMI patients) and the number of hospitals in which the physician treated AMI patients were also included in the analysis.
Hospital characteristics included whether a hospital had advanced cardiac capabilities including PTCA and coronary bypass surgery. Other factors included the teaching status of a hospital, the number of infarct patients treated at a hospital and whether a hospital was located in a rural or in an urban area. The percent of the physicians at a hospital that treat AMI patients who are cardiologists was also analyzed. The type of insurance for each patient was provided by the hospital based on the primary payer billed for the hospitalization. These data were not verified by the individual payers. These included Medicare, Medicaid, traditional indemnity separated into Blue Cross and commercial, health maintenance organization (HMO) also separated into Blue Cross and commercial and a miscellaneous group encompassing self pay, workers compensation and government insurance other than Medicare or Medicaid.
Chi-square and Students t tests were used to test differences in baseline characteristics between patients treated by cardiologists and primary care physicians. Length of stay data are presented as comparison of geometric mean length of stay between cardiologists and primary care providers.
| Results |
|---|
|
|
|---|
|
|
|
Physician volume. The median number of infarct patients treated by a physician in this study population was 12 and a high-volume physician was defined as one who treated more than 12 patients. By multivariate analysis, after accounting for patient characteristics and treatment by a cardiologist, physician treatment of a high-volume of AMI patients was an independent predictor of lower in-hospital mortality (odds ratio = 0.89 [CI 0.80 to 0.99], p < 0.03).
Hospital and payer characteristics. Of the hospital and payer variables tested after accounting for patient characteristics and physician volume and specialty, the location of the hospital was identified as an independent predictor of in-hospital mortality (p < 0.006). In-hospital mortality was higher for hospitals in a 100% urban, 75% to 99% urban or 100% rural location. Insurance type was also an independent predictor of in-hospital mortality (p < 0.04), with higher mortality seen in Medicaid, Medicare, commercial HMO and the miscellaneous payer groups. The identification of an independent predictor for a categorical variable means that statistical differences exist among some of the levels with respect to in-hospital mortality; it does not imply all levels of the factor are statistically different from each other.
Length of stay. The geometric mean length of stay according to specialty is outlined in Table 4. When the patients are grouped as to whether revascularization was performed, patients treated by cardiologists had significantly shorter length of stay for both patients undergoing PTCA or coronary artery bypass graft surgery (CABG) as well as those treated medically.
|
| Discussion |
|---|
|
|
|---|
A previous study conducted in four states (Alabama, Connecticut, Iowa and Wisconsin) found that cardiologists achieve better outcomes in caring for Medicare patients with AMI (8). The present study extends these findings to patients of all ages who presented with a myocardial infarction in a large state (Pennsylvania) with a mixture of urban and rural populations. Jollis et al. (8) suggested that the explanation for the better outcome by cardiologists may be related to their additional training and experience with patients who have coronary disease. They found that cardiologists were more likely to use medications which have been shown to improve survival following an AMI. Also, cardiologists utilized coronary angiography and revascularization procedures more frequently and identified more patients with severe coronary disease who were most likely to have improved survival with revascularization. Selby et al. (12) recently reported more favorable outcomes in AMI patients treated at hospitals with higher rates of angiography.
Volume of AMI patients treated by a physician. The present study identified physician volume as an independent predictor of lower in-hospital mortality. Previous studies of CABG (1315) and PTCA (16) have identified the important relationship of physician volume to outcome. This appeared to be a logical finding in the performance of these highly technical procedures. The present study extends that observation to the treatment of myocardial infarction in which a high volume is associated with better outcome. Physicians who treat more AMI patients are more likely to be knowledgeable about current therapies and may identify complications and intervene at an earlier time.
The data suggest that primary care physicians can achieve better outcomes by caring for a higher volume of AMI patients. It is important to note that approximately 85% of cardiologists were high-volume physicians as compared to 31% of primary care physicians. Therefore, in most cases, there is an additional survival benefit for a patient treated by a cardiologist, since the specialist is very likely to be a physician who cares for a high volume of AMI patients.
Location of hospital as a risk factor. Hospital location in a 100% urban area was associated with worse outcome. In Pennsylvania, Philadelphia County is the only one considered to be 100% urban and this county has a large indigent population which may impact their overall care process. Despite the predominance of teaching and university hospitals in the 100% urban and dominantly urban areas, patient outcome was worse. While the worse outcome of myocardial infarction in 100% urban hospitals may reflect the well-known association between lower socioeconomic status and higher rates of cardiovascular events and death, it also raises questions in regards to the process of care received by patients in a system where residents and fellows are often the initial caregivers. This may in some cases cause delay in proceeding with early life-saving reperfusion therapies. The higher mortality seen in rural hospitals may reflect the lack of on-site availability of procedures for the management of complications including PTCA and coronary bypass surgery.
Payer type and outcome. The results suggest that patients covered by certain types of insurance have higher mortality independent of clinical severity. One would expect the Medicare and Medicaid groups to have an increased severity of illness, and it is possible that the models did not completely account for these differences.
There may be other unmeasured characteristics contributing to differences in mortality, such as patients who are more health conscious and hence pursuing a variety of better life-style and medical care habits that are clustered in particular insurance products. There may be unmeasured differences in doctors or hospitals participating in the various insurance options that might have affected outcomes. Since the payer data were provided by the hospital and not verified by the individual payers, this portion of the analysis needs to be viewed with caution. Further analysis is needed to better understand the relationship between different payer types and mortality, especially with the changing role of payers in health care delivery.
Differences in length of stay. The length of stay was significantly lower for patients treated by cardiologists regardless of whether medical therapy or a revascularization procedure was performed. Since cardiologists are more likely to be aware of effective therapies in the treatment of AMI patients, this may lead to more rapid initiation of therapy and stabilization of the patient, thus allowing for earlier discharge from the hospital.
Statistical model. There were significant differences in baseline clinical characteristics for patients treated by cardiologists as compared to primary care physicians including age, gender and presence of diabetes mellitus. With increased age often being associated with comorbid conditions, it is important to emphasize that these conditions, along with age, were heavily weighted as risk adjustment factors in the statistical model. While the worse outcome of primary care treated AMI patients is similar in the previous report of Medicare patients by Jollis et al. (8) and in the present report of patients from 30 to 99 years of age in Pennsylvania, it will be important to assess the consistency of this result in other populations.
Conclusions. Based on data for all initial hospitalizations for myocardial infarction in the Commonwealth of Pennsylvania in 1993, patients with AMI treated by a cardiologist had lower mortality as compared to those treated by a primary care physician. In addition, patients of physicians who treat a high volume of AMI patients had improved survival. Hospital location and payer type also impact patient survival, and this information may be helpful in shaping future policy for payers and hospitals. Cardiologists have lower length of stay compared to primary care physicians for both medically treated patients and those undergoing revascularization. These results have important implications for optimal treatment of AMI in the current transformation of the health care delivery system.
| Acknowledgments |
|---|
| Footnotes |
|---|
| References |
|---|
|
|
|---|
This article has been cited by other articles:
![]() |
S. M. Dunlay, K. P. Alexander, C. Melloni, J. L. Kraschnewski, L. Liang, W. B. Gibler, M. T. Roe, E. M. Ohman, and E. D. Peterson Medical Records and Quality of Care in Acute Coronary Syndromes: Results From CRUSADE Arch Intern Med, August 11, 2008; 168(15): 1692 - 1698. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. L. Daugherty, P. M. Ho, J. A. Spertus, P. G. Jones, R. G. Bach, H. M. Krumholz, E. D. Peterson, J. S. Rumsfeld, and F. A. Masoudi Association of Early Follow-up After Acute Myocardial Infarction With Higher Rates of Medication Use Arch Intern Med, March 10, 2008; 168(5): 485 - 491. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. D. Ketcham, L. C. Baker, and D. MacIsaac Physician Practice Size And Variations In Treatments And Outcomes: Evidence From Medicare Patients With AMI Health Aff., January 1, 2007; 26(1): 195 - 205. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. Hartz and P. A. James A systematic review of studies comparing myocardial infarction mortality for generalists and specialists: lessons for research and health policy. J Am Board Fam Med, May 1, 2006; 19(3): 291 - 302. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. K. Lindenauer, R. Behal, C. K. Murray, W. Nsa, P. M. Houck, and D. W. Bratzler Volume, quality of care, and outcome in pneumonia. Ann Intern Med, February 21, 2006; 144(4): 262 - 269. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. F. Sonel, C. B. Good, J. Mulgund, M. T. Roe, W. B. Gibler, S. C. Smith Jr, M. G. Cohen, C. V. Pollack Jr, E. M. Ohman, E. D. Peterson, et al. Racial Variations in Treatment and Outcomes of Black and White Patients With High-Risk Non-ST-Elevation Acute Coronary Syndromes: Insights From CRUSADE (Can Rapid Risk Stratification of Unstable Angina Patients Suppress Adverse Outcomes With Early Implementation of the ACC/AHA Guidelines?) Circulation, March 15, 2005; 111(10): 1225 - 1232. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. Bansal, V. Gaddam, Y. W. Aude, J. Bissett, I. Fahdi, L. Garza, J. Joseph, B. Molavi, B. V. Pai, A. Sinha, et al. Trends in the Care of Patients With Acute Myocardial Infarction at a University-Affiliated Veterans Afffairs Medical Center Journal of Cardiovascular Pharmacology and Therapeutics, January 1, 2005; 10(1): 39 - 44. [Abstract] [PDF] |
||||
![]() |
W. B. Fye Introduction: the origins and implications of a growing shortage of cardiologists J. Am. Coll. Cardiol., July 21, 2004; 44(2): 221 - 232. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Hirshfeld Jr and W. B. Fye Summary of Task Force recommendations to address the growing shortage of cardiologists J. Am. Coll. Cardiol., July 21, 2004; 44(2): 272 - 275. [Full Text] [PDF] |
||||
![]() |
P. M. Ho, F. A. Masoudi, E. D. Peterson, G. K. Grunwald, A. E. Sales, K. E. Hammermeister, and J. S. Rumsfeld Cardiology management improves secondary prevention measures among patients with coronary artery disease J. Am. Coll. Cardiol., May 5, 2004; 43(9): 1517 - 1523. [Abstract] [Full Text] [PDF] |
||||
![]() |
W. B. Fye Cardiology's Workforce Shortage: Implications for Patient Care and Research Circulation, February 24, 2004; 109(7): 813 - 816. [Full Text] [PDF] |
||||
![]() |
I. A. SCOTT, K. HEATH, C. HARPER, and A. CLOUGH An Australian comparison of specialist care of acute myocardial infarction Int. J. Qual. Health Care, March 1, 2003; 15(2): 155 - 161. [Abstract] [Full Text] [PDF] |
||||
![]() |
P Block, H Weber, P Kearney, and on behalf of the Cardiology Section of the UEMS Manpower in cardiology II in western and central Europe (1999-2000) Eur. Heart J., February 2, 2003; 24(4): 299 - 310. [Full Text] [PDF] |
||||
![]() |
M. Ansari, M. Alexander, A. Tutar, D. Bello, and B. M. Massie Cardiology participation improves outcomes in patients with new-onset heart failure in the outpatient setting J. Am. Coll. Cardiol., January 1, 2003; 41(1): 62 - 68. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Z. Ayanian, M. B. Landrum, E. Guadagnoli, and P. Gaccione Specialty of Ambulatory Care Physicians and Mortality among Elderly Patients after Myocardial Infarction N. Engl. J. Med., November 21, 2002; 347(21): 1678 - 1686. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. H. Mehta, D. A. Criger, C. B. Granger, K. K. Pieper, R. M. Califf, E. J. Topol, and E. R. Bates Patient outcomes after fibrinolytic therapy for acute myocardial infarction at hospitals with and without coronary revascularization capability J. Am. Coll. Cardiol., September 18, 2002; 40(6): 1034 - 1040. [Abstract] [Full Text] [PDF] |
||||
![]() |
E. A. Halm, C. Lee, and M. R. Chassin Is Volume Related to Outcome in Health Care? A Systematic Review and Methodologic Critique of the Literature Ann Intern Med, September 17, 2002; 137(6): 511 - 520. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. H. Mehta, C. K. Montoye, M. Gallogly, P. Baker, A. Blount, J. Faul, C. Roychoudhury, S. Borzak, S. Fox, M. Franklin, et al. Improving Quality of Care for Acute Myocardial Infarction: The Guidelines Applied in Practice (GAP) Initiative JAMA, March 13, 2002; 287(10): 1269 - 1276. [Abstract] [Full Text] [PDF] |
||||
![]() |
Y. Elad, W. J. French, D. M. Shavelle, L. S. Parsons, M. J. Sada, N. R. Every, and Participants in the National Registry of Myocardia Primary angioplasty and selection bias inpatients presenting late (>12 h) after onset of chest pain and ST elevation myocardial infarction J. Am. Coll. Cardiol., March 6, 2002; 39(5): 826 - 833. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. J. McNeil Hidden Barriers to Improvement in the Quality of Care N. Engl. J. Med., November 29, 2001; 345(22): 1612 - 1620. [Full Text] [PDF] |
||||
![]() |
R. H. Mehta, S. S. Rathore, M. J. Radford, Y. Wang, Y. Wang, and H. M. Krumholz Acute myocardial infarction in the elderly: differences by age J. Am. Coll. Cardiol., September 1, 2001; 38(3): 736 - 741. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. Bellotti, L.P. Badano, N. Acquarone, R. Griffo, G. Lo Pinto, A.P. Maggioni, C. Mattiauda, G. Menardo, and P. Mombelloni Specialty-related differences in the epidemiology, clinical profile, management and outcome of patients hospitalized for heart failure. The OSCUR study Eur. Heart J., April 1, 2001; 22(7): 596 - 604. [Abstract] [PDF] |
||||
![]() |
A. D. Auerbach, M. B. Hamel, R. M. Califf, R. B. Davis, N. S. Wenger, N. Desbiens, L. Goldman, H. Vidaillet, A. F. Connors, J. Lynn, et al. Patient characteristics associated with care by a cardiologist among adults hospitalized with severe congestive heart failure J. Am. Coll. Cardiol., December 1, 2000; 36(7): 2119 - 2125. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. D. Vu, R. F Heller, L. L-Y Lim, C. D'Este, and R. L O'Connell Mortality after acute myocardial infarction is lower in metropolitan regions than in non-metropolitan regions J. Epidemiol. Community Health, August 1, 2000; 54(8): 590 - 595. [Abstract] [Full Text] |
||||
![]() |
R. A. Dudley, K. L. Johansen, R. Brand, D. J. Rennie, and A. Milstein Selective Referral to High-Volume Hospitals: Estimating Potentially Avoidable Deaths JAMA, March 1, 2000; 283(9): 1159 - 1166. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. D. Auerbach, M. B. Hamel, R. B. Davis, A. F. Connors Jr., C. Regueiro, N. Desbiens, L. Goldman, R. M. Califf, N. V. Dawson, N. Wenger, et al. Resource Use and Survival of Patients Hospitalized with Congestive Heart Failure: Differences in Care by Specialty of the Attending Physician Ann Intern Med, February 1, 2000; 132(3): 191 - 200. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. R. Thiemann, J. Coresh, W. J. Oetgen, and N. R. Powe The Association between Hospital Volume and Survival after Acute Myocardial Infarction in Elderly Patients N. Engl. J. Med., May 27, 1999; 340(21): 1640 - 1648. [Abstract] [Full Text] [PDF] |
||||
![]() |
Cardiologist-Treated Patients Have Lower MI Mortality Journal Watch Cardiology, October 16, 1998; 1998(1016): 7 - 7. [Full Text] |
||||
![]() |
Do Cardiologists Achieve Better Outcomes in MI? Journal Watch (General), October 16, 1998; 1998(1016): 5 - 5. [Full Text] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | SUBSCRIPTIONS | CURRENT ISSUE | PAST ISSUES | CARDIOSOURCE | SEARCH | HELP | FEEDBACK |