Abstract
OBJECTIVE: To determine the extent to which resource use for patients hospitalized with acute myocardial infarction varies with clinical status, and to see if an observed difference in resource use between two states can be explained by clinically detailed risk adjustment.
DESIGN: Retrospective review of the clinical characteristics and resource use of 342 patients hospitalized in two states with acute myocardial infarction.
DATA SOURCES: Merged data from three sources: a large, existing research database used in developing the Medicare Mortality Predictor Score, clinical data abstracted from medical charts specifically for this study, and Medicare Parts A and B claims records.
PATIENTS: A probability sample of Medicare patients hospitalized in 1986 with a diagnosis of acute myocardial infarction and residing in either Wisconsin or Washington state; patients dying within 30 days are oversampled.
MEASUREMENTS AND MAIN RESULTS: Although patients were clinically similar in the two states, there were systematic differences in resource use. Patients in Wisconsin spent more than one extra day in the intensive care unit (ICU) (2.8 vs 1.7) as well as more than one extra non-ICU day in the hospital (8.0 vs 6.3) than patients in Washington. Patients in Wisconsin were also more likelyto receive an echocardiogram (35.6% vs 15.8%), nuclear ventriculogram (12.8% vs 4.1%), exercise tolerance test (21.5% vs 3.4%), and Hotter monitoring (5.4% vs 0%). (All p<.01.) Differences in utilization were greater for patients at lower risk of dying. The average cost of care was 20.8% higher in Wisconsin (p=.01); risk adjustment for clinical and other factors reduced this difference to 11.8%, but did not eliminate it (p=.04).
CONCLUSIONS: Patients with acute myocardial infarction vary in resource use as a function of clinical factors present at admission and occurring during the hospital stay; comparisons that do not take account of these factors may not discriminate well between providers who care for sicker patients and those who are inefficient. The greater use of resources for patients in Wisconsin is at least partially explained by differences in clinical characteristics that are not presently captured in administrative data.
Similar content being viewed by others
References
Wennberg JE, Gittelsohn A. Small area variations in health care delivery. Science. 1973;182:1102–8.
Wennberg JE. Future directions for small area variations. Med Care. 1993;31:YS75–80.
Goldberg KC, Hartz AJ, Jacobsen SJ. Krakauer H, Rimm AA. Racial and community factors influencing coronary artery bypass graft surgery rates for all 1986 medicare patients. JAMA. 1992;267:1473–7.
Peterson ED. Wright SM, Daley JD, Thibault GE. Racial variation in cardiac procedure use and survival following acute myocardial infarction in the Department of Veterans Affairs. JAMA. 1994;271:1175–80.
Shaw LJ, Miller DD, Romeis JC, et al. Gender differences in the non-invasive evaluation and management of patients with suspected coronary artery disease. Ann Intern Med. 1994;120:559–66.
Udvarhelyi IS, Gatsonis C, Epstein AM, Pashos C, Newhouse JP, McNeil BJ. Acute myocardial infarction in the Medicare population. JAMA. 1992;268:2530–6.
Every NR, Larson EB, Litwin PE, et al. The association between on-site cardiac catheterization facilities and the use of coronary angiography after acute myocardial infarction. N Engl J Med. 1993;329:546–51.
Jencks SF, Daley J, Draper D, et al. Interpreting hospital mortality data. JAMA. 1988;260:3611–6.
Daley J, Jencks S, Draper D, et al. Predicting hospital-associated mortality for Medicare patients. JAMA. 1988;260:3617–24.
Alpert JS, Braunwald E. Acute myocardial infarction: pathological, pathophysiological, and clinical manifestations. In: Braunwald E, ed. Heart Disease: A Textbook of Cardiovascular Medicine. Philadelphia, Pa: WB Saunders Co; 1984;1262.
Knaus WA, Draper EA, Wagner DP, Zimmerman JE. APACHE II: a severity of disease classification system. Crit Care Med. 1985;13:818–29.
Cleary PD, Greenfield S, Mulley AG, et al. Variations in length of stay and outcomes for six medical and surgical conditions in Massachusetts and California. JAMA. 1991;266:73–9.
Chen E, Naylor D. Variation in hospital length of stay for acute myocardial infarction in Ontario, Canada. Med Care. 1994;32:420–35.
Welch WP, Miller ME, Welch HG, Fisher ES, Wennberg JE. Geographic variation in expenditures for physicians’ services in the United States. N Engl J Med. 1993;328:621–7.
Welch HG, Miller ME, Welch WP. Physician profiling: an analysis of inpatient practice patterns in Florida and Oregon. N Engl J Med. 1994;330:607–12.
McPherson K, Wennberg JE, Hovind OB, Clifford P. Small-area variations in the use of common surgical procedures: an international comparison of New England, England, and Norway. N Engl J Med. 1982;307:1310–4.
Wennberg JE. Unwanted variations in the rules of practice. JAMA. 1991;265:1306–7.
Keller RB, Soule DN, Wennberg JE, Hanley DF. Dealing with geographic variations in the use of hospitals. J Bone Joint Surg. 1990;72:1286–93.
Wennberg JE. Population illness rates do not explain population hospitalization rates: a comment on Mark Blumberg’s thesis that morbidity adjusters are needed to interpret small area variations. Med Care. 1987;25:354–9.
Bucher HC. Social supports and prognosis following first myocardial infarction. J Gen Intern Med. 1994;9:409–17.
Author information
Authors and Affiliations
Additional information
This work was supported by the Health Care Financing Administration, Office of Research, under cooperative agreement 99-C-99169/5-03.
Rights and permissions
About this article
Cite this article
Du, W., Ash, A.S., Berlowitz, D.R. et al. Variations in the management of acute myocardial infarction. J Gen Intern Med 11, 334–341 (1996). https://doi.org/10.1007/BF02600043
Issue Date:
DOI: https://doi.org/10.1007/BF02600043