Special Article
The Association between Hospital Volume and Survival after Acute Myocardial Infarction in Elderly Patients
N Engl J Med 1999; 340:1640-1648May 27, 1999
- Abstract
Background
Patients with chest pain thought to be due to acute coronary ischemia are typically taken by ambulance to the nearest hospital. The potential benefit of field triage directly to a hospital that treats a large number of patients with myocardial infarction is unknown.
Methods
We conducted a retrospective cohort study of the relation between the number of Medicare patients with myocardial infarction that each hospital in the study treated (hospital volume) and long-term survival among 98,898 Medicare patients 65 years of age or older. We used proportional-hazards methods to adjust for clinical, demographic, and health-system–related variables, including the availability of invasive procedures, the specialty of the attending physician, and the area of residence of the patient (rural, urban, or metropolitan).
Results
The patients in the quartile admitted to hospitals with the lowest volume were 17 percent more likely to die within 30 days after admission than patients in the quartile admitted to hospitals with the highest volume (hazard ratio, 1.17; 95 percent confidence interval, 1.09 to 1.26; P<0.001), which resulted in 2.3 more deaths per 100 patients. The crude mortality rate at one year was 29.8 percent among the patients admitted to the lowest-volume hospitals, as compared with 27.0 percent among those admitted to the highest-volume hospitals. There was a continuous inverse dose–response relation between hospital volume and the risk of death. In an analysis of subgroups defined according to age, history of cardiac disease, Killip class of infarction, presence or absence of contraindications to thrombolytic therapy, and time from the onset of symptoms, survival at high-volume hospitals was consistently better than at low-volume hospitals. The availability of technology for angioplasty and bypass surgery was not independently associated with overall mortality.
Conclusions
Patients with acute myocardial infarction who are admitted directly to hospitals that have more experience treating myocardial infarction, as reflected by their case volume, are more likely to survive than are patients admitted to low-volume hospitals.
Media in This Article
Figure 1
Crude Kaplan–Meier 30-Day Survival Curves, by Quartile, According to Hospital Volume of Medicare Patients with Acute Myocardial Infarction.Figure 2
Stratified Proportional-Hazards Ratios for Long-Term Mortality According to Potentially Confounding Factors Pertaining to the Health System.Article Activity
- Article
In most of the United States, patients with chest pain thought to be due to acute coronary ischemia are taken by ambulance to the nearest hospital rather than to tertiary centers that treat a large number (high volume) of patients with acute myocardial infarction. The destination is determined by proximity alone, both for efficient operation of the emergency medical transportation system and because time is deemed paramount.
The importance of experience on the part of the hospital and physician as a determinant of the patient's survival has been increasingly recognized for various specialties and procedures.1-9 To determine whether hospital volume influences mortality among patients with acute myocardial infarction, we performed a retrospective cohort study, using data from the Cooperative Cardiovascular Project (CCP), which was conducted by the Health Care Financing Administration (HCFA). This cohort was uniquely suited for the analysis of the effects of aspects of the health care delivery system: the nationwide sample comprised nearly 100 percent of elderly patients with myocardial infarction who had fee-for-service insurance coverage, and the study had extensive clinical data, blinded data abstraction, and reliable long-term follow-up.
Methods
The methods of the CCP are described fully elsewhere.10-12 For each acute care hospital in the United States, HCFA identified all Medicare fee-for-service beneficiaries with the principal-discharge-diagnosis code 410.xx (acute myocardial infarction), excluding codes 410.x2 (subsequent care), of the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM), during a continuous eight-month sampling period that fell between February 1994 and July 1995. Using photocopied medical-record charts, research abstracters entered pertinent historical, clinical, and demographic variables into an electronic data base.
Patients
By virtue of geography and the policy of the emergency medical system, most patients with acute myocardial infarction are taken to the nearest hospital. To reduce potential biases in selection and referral of patients, we limited the analysis to patients 65 years of age or older who were admitted from home with a verified infarction that was present on admission. We excluded duplicate admissions, interhospital transfers, and admissions from nursing and retirement homes. We also excluded patients whose infarctions occurred after admission, those referred from physicians' offices and free-standing clinics, and patients with coma on arrival or with preexisting dementia or terminal illness. We excluded patients from five states (Alabama, Connecticut, Iowa, Minnesota, and Wisconsin) because of intentional undersampling related to other CCP research projects. We obtained demographic data for the county of residence by linking the postal ZIP codes of the patients to governmental data bases.13-16 Data on long-term survival, obtained from the enrollment data base of the Social Security Administration, were assigned to the initial admitting hospital regardless of subsequent transfer.
Myocardial infarction was deemed present if patients had a creatine kinase MB fraction greater than 0.05 or at least two of the following three criteria: chest pain, a serum creatine kinase level at least two times the upper limit of normal, or diagnostic electrocardiographic findings. We used dummy variables to code missing values for categorical variables and for continuous variables with a rate of missing values greater than 5 percent. The results were unchanged in several alternative analyses that did not include dummy variables.
Data on Hospitals and Physicians
Our unit of analysis was an individual patient from the CCP. For each patient, we constructed a variable for the total number of CCP patients at the admitting hospital. We determined the availability of invasive procedures at each hospital according to the capability for coronary angiography or revascularization (no angiography, angiography only, or angioplasty and bypass surgery), assuming that hospitals billing for more than four procedures during the study had on-site capability. We obtained information on the other characteristics of the hospitals from the data base of the American Hospital Association.17
We determined the specialty of the physician by matching the unique physician identification numbers of CCP attending physicians to a HCFA data base of self-reported specialties. We limited the analysis of specialists to cardiologists, internists, family practitioners, and general practitioners, who were the attending physicians for 82.3 percent of the patients in the study.
Statistical Analysis
Our multivariate model, adapted from models for the assessment of 30-day mortality after myocardial infarction reported by Normand et al.18 and Lee et al.,19 included clinical, historical, and health-system–related variables. To the published models we added variables for hospital volume and availability of invasive procedures, specialty of the attending physician, presence or absence of electrocardiographic ST-segment elevation, presence or absence of contraindications to thrombolytic therapy, area of residence of the patient (rural, urban, or metropolitan), and geographic region (northeast, south, midwest, and west). Each clinical variable was significant at the level of P<0.001, with the exception of a third heart sound (S3) on admission (P=0.01). None of the independent variables were collinear (Spearman correlations, <0.5).
We divided the patient population into quartiles according to the case volume of the hospitals to which they were admitted and used Kaplan–Meier curves to compare unadjusted survival. To determine whether there was a selection bias, we used logistic regression to calculate a predicted one-year mortality rate20 for each quartile of hospital volume and for each physician specialty. We used data on covariates for each patient from the proportional-hazards model while neutralizing the effects of hospital-related variables by standardizing them to the lowest-mortality groups. Thus, hospital volume was standardized to the median of the highest-volume quartile, the specialty of cardiology, the availability of bypass surgery, the patient's residence in a major metropolitan county, and the northeastern geographic region. We excluded the possibility that within-hospital clustering might affect the results, because the results of logistic regression,21 the generalized estimating equation,22,23 and the Cox proportional-hazards survival analysis24 were virtually identical. Hospital volume was scaled to the difference between the medians of the lowest and highest quartiles (5.5 Medicare patients with myocardial infarction per week), approximating the maximal potential benefit of field triage for patients with myocardial infarction.
Results
Characteristics of the Patients
The original data set contained information on 234,769 admissions. We excluded admissions from the five undersampled states (4.2 percent); admissions after the index admission (11.0 percent); patients admitted from places other than home (25.0 percent); patients who did not have a verified infarction on admission (10.0 percent); patients admitted to hospitals that were able to provide emergency angioplasty without bypass surgery (2.7 percent); and patients younger than 65 years (5.0 percent).
Overall, 98,898 patients met the criteria for the study. Data on 3713 (3.8 percent) of these patients were excluded from the multivariate analysis because of missing information. The rates of missing information for variables describing clinical characteristics were less than 5 percent with the exception of the rates for serum albumin (27.0 percent) and chest radiographs (6.0 percent). Analyses that included the physician's specialty excluded 750 patients (0.8 percent) for whom information on the specialty was not available. The median follow-up period for survivors was 910 days.
Demographic and clinical characteristics of the patients in the study, by quartile, according to hospital volume, are shown in Table 1Table 1
Characteristics and Outcomes of the Study Patients, by Quartile, According to the Hospital's Volume of Patients with Acute Myocardial Infarction.. Most differences were significant at the level of P<0.001, but their magnitude and clinical significance were small, with predictable exceptions. A higher proportion of patients at low-volume hospitals had rural ZIP codes, patients at high-volume hospitals tended to be city dwellers, and high-volume hospitals were more likely to offer treatment by cardiologists as well as coronary angiography and revascularization.Survival
Unadjusted Kaplan–Meier survival curves for quartiles of hospital volume (Figure 1Figure 1
Crude Kaplan–Meier 30-Day Survival Curves, by Quartile, According to Hospital Volume of Medicare Patients with Acute Myocardial Infarction.) showed an early survival advantage at high-volume hospitals. Thirty days after discharge, the unadjusted mortality rate was 16.7 percent at the lowest-volume centers, as compared with 14.4 percent at the highest-volume centers, with a progressive dose–response effect. The association between higher mortality and admission to hospitals treating a small number of patients with myocardial infarction (low volume) remained significant in a proportional-hazards analysis (Table 2Table 2
Adjusted Hazard Ratios for Death Associated with Variables Pertaining to the Hospitals and Physicians.): a decrease of 5.5 Medicare patients per week was associated with a hazard ratio for death at 30 days of 1.10 (95 percent confidence interval, 1.05 to 1.16; P<0.001) and a long-term hazard ratio for death of 1.05 (95 percent confidence interval, 1.02 to 1.08; P<0.001).In an otherwise identical model that treated hospital volume as an ordinal variable according to quartile, the hazard ratio for 30-day survival among patients in the lowest versus the highest hospital-volume quartile was 1.17 (95 percent confidence interval, 1.09 to 1.26; P<0.001); for the second quartile the ratio was 1.07 (95 percent confidence interval, 1.01 to 1.13; P= 0.02); and for the third quartile the ratio was 1.05 (95 percent confidence interval, 0.99 to 1.10; P=0.11). By comparison, the hazard ratio for 30-day survival was 1.09 for patients who had had prior bypass surgery and 1.18 for patients with a history of diabetes mellitus. The risk of death was disproportionately high at low-volume hospitals, but hospital volume as a continuous variable remained significant when the analysis was limited to the two highest-volume quartiles.
The association between hospital volume and mortality was not due to imbalances among the quartiles in coexisting conditions or the severity of the illness. The predicted 30-day and 1-year mortality rates, which neutralize the effects of health-system factors (Table 1), were essentially identical in all quartiles of hospital volume. Subgroup analyses according to the demographic and clinical characteristics of the patients at presentation (Table 3Table 3
Thirty-Day Mortality Rates and Adjusted Hazard Ratios for Death at 30 Days, According to Clinical Characteristics of Patients at Presentation.) showed that survival at low-volume hospitals was consistently worse than at high-volume hospitals.Availability of Invasive Procedures, Physician Specialty, and Rural Residence
The availability of invasive procedures, after adjustment for hospital volume and the physician's specialty, was not associated with a significant survival advantage. For each type of hospital invasive procedure, there was a dose–response relation between hospital volume of patients with myocardial infarction and long-term survival (Figure 2Figure 2
Stratified Proportional-Hazards Ratios for Long-Term Mortality According to Potentially Confounding Factors Pertaining to the Health System., top). When hospital volume was treated as a continuous variable, the dose–response relation for survival within 30 days after admission was highly significant at hospitals that did not offer angiography (hazard ratio, 1.38 for a decrease of 5.5 patients with myocardial infarction per week; 95 percent confidence interval, 1.16 to 1.63; P<0.001) and at hospitals that offered only angiography (hazard ratio, 1.19; 95 percent confidence interval, 1.06 to 1.34; P<0.01). The hazard ratio for volume plateaued among hospitals that offered bypass surgery and angioplasty, with borderline statistical significance (hazard ratio, 1.07; 95 percent confidence interval, 1.01 to 1.13; P=0.02). Figure 2 (top) confirms that no significant survival advantage can be attributed to hospital invasive procedures alone, because there was a substantial overlap of hazard ratios for long-term mortality among hospitals with different technological capability but equivalent volume, a finding confirmed by statistical analysis of interaction. After adjustment for volume, there was no significant association between survival and the hospital's number of beds or teaching status.Altogether, 30.0 percent of the patients had cardiologists as attending physicians, 37.0 percent had internists, and 15.3 percent had family practitioners. The patients treated by cardiologists were considerably healthier than the patients treated by other specialists, with a logistic predicted one-year mortality of 23.0 percent, as compared with 26.9 percent for patients treated by internists, a trend found previously.25 There was a small long-term survival advantage for patients of cardiologists, with a long-term hazard ratio for death of 0.97 (95 percent confidence interval, 0.94 to 1.00; P=0.02). The specialty of the attending physician did not affect the association between hospital volume and survival, which had a dose–response relation for patients of each type of specialist (Figure 2, middle). The benefit of having a cardiologist as an attending physician was essentially the same among hospitals that could not provide angiography, those that could provide only angiography, and those that could provide angioplasty and bypass surgery. During the eight-month sampling period, each cardiologist treated a median of six Medicare patients with myocardial infarction, as compared with a median of three for each internist, and a median of two for each family practitioner and general practitioner. The number of patients treated by the attending physician was not significant in any of the analyses, which included the physician's specialty, excluded the specialty, or were restricted to a particular specialty.
Living in a less populous region as opposed to a metropolitan area was an independent risk factor for short- and long-term mortality (Figure 2, bottom). Hazard ratios for death at 30 days were 1.11 for rural counties (95 percent confidence interval, 1.06 to 1.17; P<0.001) and 1.06 for urban counties in metropolitan statistical areas with a population of 1 million or less (95 percent confidence interval, 1.02 to 1.11; P=0.005). Population density did not affect the association between hospital volume and survival, which had a dose–response relation within each demographic subgroup.
Patterns of Hospital Practice
Only part of the survival advantage at high-volume hospitals was explained by measurable differences in the quality of care. When we added to our basic model separate variables for each patient's receipt of aspirin and thrombolytic medications on admission and beta-blockers and angiotensin-converting–enzyme inhibitors at discharge, the hazard ratio for death at 30 days associated with lower hospital volume at hospitals that did not offer on-site angiography decreased from 1.38 to 1.23 (95 percent confidence interval, 1.04 to 1.46; P=0.02). At hospitals that offered angiography only, the hazard ratio, 1.17, was essentially unchanged (95 percent confidence interval, 1.04 to 1.31; P=0.008). At hospitals that offered bypass surgery, the ratio decreased from 1.07 to 1.02 (P=0.60). The diminution was due largely to the use of aspirin and beta-blockers, a finding consistent with the results of prior studies.11,26 The hazard ratio associated with lower hospital volume did not change when revascularization within 30 days (including angioplasty or bypass surgery at another hospital) was added to the model, despite considerable variation in revascularization rates: 24 percent at hospitals without angiography, 29 percent at hospitals with angiography only, and 42 percent at hospitals with angioplasty and bypass surgery.
Discussion
We found that elderly patients with acute myocardial infarction have better outcomes when they are admitted directly to hospitals that treat a large number of patients with acute coronary syndromes than when they are admitted to hospitals that treat a small number of such patients. The crude difference in 30-day mortality between patients in the lowest and highest quartiles of hospital volume was 2.3 deaths per 100 patients. There was a consistent dose–response relation between hospital volume and survival. There was virtually no change in the mortality differential after adjustment for clinical factors, the availability of invasive procedures, the physician's specialty, and the patient's county of residence.
Although the hazard associated with low hospital volume is smaller for patients with myocardial infarction than for patients undergoing surgical procedures,1,3-9 the mortality attributable to hospital volume is considerable, because the population at risk is large and because mortality from cardiac causes is high among the elderly. For nearly half the Medicare patients with myocardial infarction nationwide, the 30-day survival benefit at high-volume centers exceeds both a 1 percent absolute difference in mortality, the threshold generally applied to trials of thrombolytic drugs,27 and the benefit found in landmark trials of medical therapy for acute myocardial infarction.28 Equally important, the survival advantage at high-volume hospitals applies to all patients with acute myocardial infarction, not only to patients who are eligible for a particular therapy; the CCP is a nationwide study of actual clinical practice rather than a study of efficacy.
In our study, the availability of invasive procedures did not confer a significant survival benefit, a finding consistent with the results of prior studies.29 The principal factor determining outcome in acute myocardial infarction thus may not be invasive procedures or the physician's specialty but the availability of an experienced health care team. For high-volume hospitals, distinctions between volume and the availability of invasive procedures are immaterial, because such hospitals typically offer angioplasty and bypass surgery. But for health system planners, this finding, from data collected in 1994 and 1995, when primary angioplasty for acute myocardial infarction was in its adolescence,30,31 raises questions about the benefit of the proliferation of technology at smaller hospitals.
Our study showed a small survival advantage for patients treated by cardiologists: a long-term hazard ratio of 0.97 for death (P=0.02), as compared with the risk ratio of 0.79 for death in the hospital reported by Nash et al.,32 the odds ratio of 0.83 for death in the hospital reported by Casale et al.,33 and the hazard ratio of 0.88 for death at one year reported by Jollis et al.25 One reason for the varying estimates of the effect of attending-physicians' specialties may be that the data from Medicare Part A do not necessarily indicate the admitting physician. About 14 percent of Medicare patients with myocardial infarction reportedly have cardiologists as attending physicians after initially being admitted by noncardiologists34; such patients may have been considered at high risk and may thus have been referred to cardiologists. Another possible reason is selection bias. When we applied our proportional-hazards model to the entire CCP data set, excluding only duplicate admissions and transfers, and limited the model to variables used in the prior CCP analysis, the long-term hazard ratio for patients who had cardiologists as attending physicians was 0.90. When we applied our exclusion criteria and used the full model in Table 2, the hazard ratio changed to 0.97. Such confounding suggests that any observational analysis of acute myocardial infarction according to the physician's specialty (including our own) may be inherently limited by selection bias, perhaps because a specialization in cardiology is often a prerequisite for performing initial therapies such as thrombolysis and primary angioplasty.
We could not identify a predominant mechanism for the survival advantage at high-volume hospitals. The use of aspirin, thrombolytic agents, beta-blockers, angiotensin-converting–enzyme inhibitors, and revascularization accounted for about one third of the survival benefit. Because the experience of a health care team is multifactorial, the absence of a more specific mechanism is not surprising and is consistent with the effects of volume in other fields.1-9
From the standpoint of health policy, the existence of an effect of volume is as important as its mechanism, suggesting that field triage, with patients with myocardial infarction transported directly to high-volume centers designated for the treatment of cardiac disease, might improve survival after myocardial infarction. The possibility of field triage arouses concern about morbidity and mortality en route to hospitals and particularly about possible delays in thrombolysis for eligible patients. Published estimates of the effect of thrombolytic symptom-to-treatment delays range from 0.16 life saved per 100 patients treated per hour of earlier treatment35 to 3.3 lives per 100 patients treated per hour within 1.6 hours after the onset of symptoms.36 In any case, thrombolytic treatment is not the sole determinant of policy for the emergency medical system, because relatively few patients receive thrombolytic agents — only 19.3 percent of the CCP cohort. And even fewer patients present shortly after the onset of symptoms, when thrombolytic therapy has the greatest benefit. In the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries study, only one quarter of the patients presented within one hour after the onset of symptoms.37 As a practical matter, minor transport delays might be clinically insignificant as compared with a benefit relating to hospital volume of more than 2 lives saved per 100 patients.
The actual effect of transport time on thrombolysis is an important issue that needs to be resolved by the development and validation of criteria for triage, clinical trials, and regional adjudication by policy makers for the emergency medical system. At high-volume hospitals, earlier administration of thrombolytic agents might compensate for short transport delays; in our CCP cohort, the median interval between arrival at the hospital and the administration of thrombolytic agents was five minutes shorter for the highest-volume quartile than for the lowest-volume quartile (P<0.001). In addition, hospitals are often clustered so closely that triage would not involve appreciable transport delays, a common-sense observation supported by analysis with the use of ZIP codes as a marker for hospital proximity. Twenty-two percent of the CCP patients in metropolitan areas and 36 percent of the patients in urban areas were admitted to smaller hospitals (those treating fewer than four CCP patients with myocardial infarction per week) that had the same ZIP code as another hospital, and three quarters of such patients (74 percent and 78 percent, respectively) were treated at smaller hospitals within two ZIP-code integers of another hospital. In rural areas, field triage might be feasible in conjunction with prehospital thrombolysis, a combination that has proved effective in randomized trials.38,39
The findings of any observational study must be interpreted cautiously. The possibility of confounding of hospital volume by unmeasured variables cannot be ruled out. Our study does not include patients in managed-care plans or patients younger than 65 years. Systematic differences in ICD-9-CM coding or documentation could create bias. Technical advances in interventional cardiology, such as intracoronary stents and glycoprotein IIB/IIIA receptor antagonists, might benefit hospitals with high-technology interventions, regardless of their volume of patients.
In conclusion, we found that in the initial hospital care of patients with acute myocardial infarction, the more experience the hospital had, the better the patient's chance for survival. After comprehensive adjustment for coexisting clinical conditions, the patients in the quartile admitted to the lowest-volume hospitals were 17 percent more likely to die within 30 days after admission than those in the highest-volume quartile (P<0.001), a difference of 2.3 deaths per 100 patients. The capability of the hospitals to perform coronary angiography, angioplasty, and bypass surgery had no significant effect on survival beyond that associated with increasing volume. In regions with acceptable transport time, survival after acute myocardial infarction might be improved by the use of field triage to transport patients directly to high-volume centers designated for the treatment of cardiac disease.
Supported by grants from the Delmarva Foundation for Medical Care, the Health Care Financing Administration, and the Harry and Jeanette Weinberg Foundation. Computational and statistical assistance was provided by the General Clinical Research Center, through grants (RR00035 and RR00072) from the National Institutes of Health. The work of Dr. Powe was supported in part by a grant (K01 A600561) from the National Institute on Aging.
The analyses on which this study was based were performed under contracts (500-96-P623 and 500-96-P624) with the Health Care Financing Administration, Department of Health and Human Services. This article does not necessarily reflect the views or policies of the Department of Health and Human Services, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. government.
We are indebted to the many people and organizations nationwide that designed and conducted the Cooperative Cardiovascular Project.
Source Information
From the Departments of Medicine (D.R.T., J.C., N.R.P.), Epidemiology (J.C., N.R.P.), Biostatistics (J.C.), and Health Policy and Management (N.R.P.), the Program for Medical Technology and Practice Assessment (D.R.T.), and the Welch Center for Prevention, Epidemiology and Clinical Research (J.C., N.R.P.), Johns Hopkins University, Baltimore; Maryland HealthCare Associates, Clinton, Md. (W.J.O.); and the Delmarva Foundation for Medical Care, Easton, Md. (W.J.O.).
Address reprint requests to Dr. Thiemann at Carnegie 568, Johns Hopkins Hospital, Baltimore, MD 21287-6568.
- References
References
1
Begg CB ,Cramer LD ,Hoskins WJ ,Brennan MF . Impact of hospital volume on operative mortality for major cancer surgery. JAMA 1998;280:1747-1751
CrossRef | Web of Science | Medline2
Phibbs CS ,Bronstein JM ,Buxton E ,Phibbs RH . The effects of patient volume and level of care at the hospital of birth on neonatal mortality. JAMA 1996;276:1054-1059
CrossRef | Web of Science | Medline3
Hughes RG ,Garnick DW ,Luft HS ,McPhee SJ ,Hunt SS . Hospital volume and patient outcomes: the case of hip fracture patients. Med Care 1988;26:1057-1067
CrossRef | Web of Science | Medline4
Hannan EL ,Kilburn H Jr ,O'Donnell JF , et al. A longitudinal analysis of the relationship between in-hospital mortality in New York State and the volume of abdominal aortic aneurysm surgeries performed. Health Serv Res 1992;27:517-542
Web of Science | Medline5
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
Full Text | Web of Science | Medline6
Hannan EL ,Racz M ,Ryan TJ , et al. Coronary angioplasty volume-outcome relationships for hospitals and cardiologists. JAMA 1997;277:892-898
CrossRef | Web of Science | Medline7
Jollis JG ,Peterson ED ,Nelson CL , et al. Relationship between physician and hospital coronary angioplasty volume and outcome in elderly patients. Circulation 1997;95:2485-2491
Web of Science | Medline8
Showstack JA ,Rosenfeld KE ,Garnick DW ,Luft HS ,Schaffarzick RW ,Fowles J . Association of volume with outcome of coronary artery bypass graft surgery: scheduled vs nonscheduled operations. JAMA 1987;257:785-789[Erratum, JAMA 1987;257:2438.]
CrossRef | Web of Science | Medline9
Luft HS ,Bunker JP ,Enthoven AC . Should operations be regionalized? The empirical relation between surgical volume and mortality. N Engl J Med 1979;301:1364-1369
Full Text | Web of Science | Medline10
Marciniak TA ,Ellerbeck EF ,Radford MJ , et al. Improving the quality of care for Medicare patients with acute myocardial infarction: results from the Cooperative Cardiovascular Project. JAMA 1998;279:1351-1357
CrossRef | Web of Science | Medline11
Krumholz HM ,Radford MJ ,Wang Y ,Chen J ,Heiat A ,Marciniak TA . National use and effectiveness of beta-blockers for the treatment of elderly patients after acute myocardial infarction: National Cooperative Cardiovascular Project. JAMA 1998;280:623-629
CrossRef | Web of Science | Medline12
Cooperative Cardiovascular Project. Austin: Texas Medical Foundation, October 1998. (See http://www.usccp.org.) (See NAPS document no. 05516 for one page of supplementary material. To order, contact NAPS, c/o Microfiche Publications, 248 Hempstead Turnpike, West Hempstead, NY 11552.)
13
MSAZIP file. Upper Marlboro, Md.: Geography Division, Washington, D.C.: Census Bureau, 1997 (software).
14
Census of population and housing, 1990: summary tape file 3. Washington, D.C.: Census Bureau, 1992 (software).
15
Area resource file. Rockville, Md.: Office of Research and Planning, Bureau of Health Professions, Health Resources and Services Administration, 1995 (software).
16
ZIPFIP files. Washington, D.C.: Economic Research Service, Department of Agriculture, 1997 (software).
17
1994 Annual survey of hospitals data base. Chicago: American Hospital Association, 1997 (software).
18
Normand ST ,Glickman ME ,Sharma RG ,McNeil BJ . Using admission characteristics to predict short-term mortality from myocardial infarction in elderly patients: results from the Cooperative Cardiovascular Project. JAMA 1996;275:1322-1328
CrossRef | Web of Science | Medline19
Lee KL ,Woodlief LH ,Topol EJ , et al. Predictors of 30-day mortality in the era of reperfusion for acute myocardial infarction: results from an international trial of 41,021 patients. Circulation 1995;91:1659-1668
Web of Science | Medline20
Nieto FJ ,Coresh J . Adjusting survival curves for confounders: a review and a new method. Am J Epidemiol 1996;143:1059-1068
Web of Science | Medline21
Hosmer DW Jr, Lemeshow S. Applied logistic regression. New York: John Wiley, 1989.
22
Liang K-Y ,Zeger SL . Longitudinal data analysis using generalized linear models. Biometrika 1986;73:13-22
CrossRef | Web of Science23
STATA, version 5.0. College Station, Tex.: Stata, 1997 (software).
24
Cox DR . Regression models and life-tables. J R Stat Soc [B] 1972;34:187-22025
Jollis JG ,DeLong ER ,Peterson ED , et al. Outcome of acute myocardial infarction according to the specialty of the admitting physician. N Engl J Med 1996;335:1880-1887
Full Text | Web of Science | Medline26
Chen J ,Radford MJ ,Wang Y ,Marciniak TA ,Krumholz HM . Do “America's Best Hospitals“ perform better for acute myocardial infarction? N Engl J Med 1999;340:286-292
Full Text | Web of Science | Medline27
White HD ,Van de Werf FJ . Thrombolysis for acute myocardial infarction. Circulation 1998;97:1632-1646
Web of Science | Medline28
The GUSTO Investigators
Full Text | Web of Science | Medline29
Every NR ,Parsons LS ,Fihn SD , et al. Long-term outcome in acute myocardial infarction patients admitted to hospitals with and without on-site cardiac catheterization facilities. Circulation 1997;96:1770-1775
Web of Science | Medline30
Grines CL ,Browne KF ,Marco J , et al. A comparison of immediate angioplasty with thrombolytic therapy for acute myocardial infarction. N Engl J Med 1993;328:673-679
Full Text | Web of Science | Medline31
Brodie BR ,Grines CL ,Ivanhoe R , et al. Six-month clinical and angiographic follow-up after direct angioplasty for acute myocardial infarction: final results from the Primary Angioplasty Registry. Circulation 1994;90:156-162
Web of Science | Medline32
Nash IS ,Nash DB ,Fuster V . Do cardiologists do it better? J Am Coll Cardiol 1997;29:475-478
CrossRef | Web of Science | Medline33
Casale PN ,Jones JL ,Wolfe FE ,Pei Y ,Eby LM . Patients treated by cardiologists have a lower in-hospital mortality for acute myocardial infarction. J Am Coll Cardiol 1998;32:885-889
CrossRef | Web of Science | Medline34
Jollis JG ,Romano PS . Pennsylvania's Focus on heart attack -- grading the scorecard. N Engl J Med 1998;338:983-987
Full Text | Web of Science | Medline35
The Fibrinolytic Therapy Trialists' (FTT) Collaborative Group
Web of Science | Medline36
Boersma E ,Maas ACP ,Deckers JW ,Simoons ML . Early thrombolytic treatment in acute myocardial infarction: reappraisal of the golden hour. Lancet 1996;348:771-775
CrossRef | Web of Science | Medline37
Newby LK ,Rutsch WR ,Califf RM , et al. Time from symptom onset to treatment and outcomes after thrombolytic therapy. J Am Coll Cardiol 1996;27:1646-1655
CrossRef | Web of Science | Medline38
Rawles J . Halving of mortality at 1 year by domiciliary thrombolysis in the Grampian Region Early Anistreplase Trial (GREAT). J Am Coll Cardiol 1994;23:1-5
CrossRef | Web of Science | Medline39
The European Myocardial Infarction Project Group
Full Text | Web of Science | Medline
- Citing Articles (108)
Citing Articles
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Guann-Ming Chang, Shou-Hsia Cheng, Yu-Chi Tung. (2011) Impact of Cuts in Reimbursement on Outcome of Acute Myocardial Infarction and Use of Percutaneous Coronary Intervention. Medical Care 49:12, 1054-1061
CrossRef2
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Comilla Sasson, Pascal Meier, Jenny A Campbell, Jason S Haukoos, David J Magid, Todd Larabee. (2011) Improving cardiac arrest survival by providing high quality, co-ordinated care: 2010 International Liaison Committee on Resuscitation guidelines. Therapy 8:6, 721-730
CrossRef4
Curtis D. Handford, Julia M. Rackal, Anne-Marie Tynan, Damian Rzeznikiewiz, Richard H. Glazier. (2011) The association of hospital, clinic and provider volume with HIV/AIDS care and mortality: systematic review and meta-analysis. AIDS Care1-16
CrossRef5
Atsuhiko Murata, Shinya Matsuda, Toshihiko Mayumi, Masamichi Yokoe, Kazuaki Kuwabara, Yukako Ichimiya, Yoshihisa Fujino, Tatsuhiko Kubo, Kenji Fujimori, Hiromasa Horiguchi. (2011) Effect of Hospital Volume on Clinical Outcome in Patients With Acute Pancreatitis, Based on a National Administrative Database. Pancreas 40:7, 1018-1023
CrossRef6
Dawn Taniguchi, Amy Baernstein, Graham Nichol. (2011) Cardiac Arrest: A Public Health Perspective. Emergency Medicine Clinics of North America
CrossRef7
Roy C. Ziegelstein. (2011) Clinical Excellence in Cardiology. The American Journal of Cardiology 108:4, 607-611
CrossRef8
William H. Marx, Ronald Simon, Patricia OʼNeill, Marc J. Shapiro, Arthur C. Cooper, Louise Sztpulski Farrell, Jane E. McCormack, Palmer Q. Bessey, Edward Hannan. (2011) The Relationship Between Annual Hospital Volume of Trauma Patients and In-Hospital Mortality in New York State. The Journal of Trauma: Injury, Infection, and Critical Care 71:2, 339-346
CrossRef9
Julia M Rackal, Anne-Marie Tynan, Curtis D Handford, Damian Rzeznikiewiz, Ayda Agha, Richard Glazier, Julia M Rackal. 2011. Provider training and experience for people living with HIV/AIDS. .
CrossRef10
J Waldman, Steven Yourstone. 2011. Learning and Thinking Systems. , 37-56.
CrossRef11
Atsuhiko Murata, Shinya Matsuda, Kazuaki Kuwabara, Yoshihisa Fujino, Tatsuhiko Kubo, Kenji Fujimori, Hiromasa Horiguchi. (2011) An Observational Study Using a National Administrative Database to Determine the Impact of Hospital Volume on Compliance With Clinical Practice Guidelines. Medical Care 49:3, 313-320
CrossRef12
Atsuhiko Murata, Shinya Matsuda, Kazuaki Kuwabara, Yoshihisa Fujino, Tatsuhiko Kubo, Kenji Fujimori, Hiromasa Horiguchi. (2010) Impact of hospital volume on clinical outcomes of endoscopic biliary drainage for acute cholangitis based on the Japanese administrative database associated with the diagnosis procedure combination system. Journal of Gastroenterology 45:10, 1090-1096
CrossRef13
Elizabeth H. Bradley, Jeph Herrin, Leslie Curry, Emily J. Cherlin, Yongfei Wang, Tashonna R. Webster, Elizabeth E. Drye, Sharon-Lise T. Normand, Harlan M. Krumholz. (2010) Variation in Hospital Mortality Rates for Patients With Acute Myocardial Infarction. The American Journal of Cardiology 106:8, 1108-1112
CrossRef14
Jeffrey H. Silber, Paul R. Rosenbaum, Tanguy J. Brachet, Richard N. Ross, Laura J. Bressler, Orit Even-Shoshan, Scott A. Lorch, Kevin G. Volpp. (2010) The Hospital Compare Mortality Model and the Volume-Outcome Relationship. Health Services Research 45:5p1, 1148-1167
CrossRef15
Jolanda Lammers, Daphne Veninga, Peter Speelman, Joost Hoekstra, Kiki Lombarts. (2010) Performance of Dutch hospitals in the management of splenectomized patients. Journal of Hospital Medicine 5:8, 466-470
CrossRef16
Ertugrul Okuyan, Ahmet Uslu, Mustafa O. Levent, Irfan Sahin, Mustafa H. Dinckal. (2010) Caring of ST-elevation myocardial infarction patients in rural community hospital settings: Determinants of in-hospital mortality. Australian Journal of Rural Health 18:4, 173-178
CrossRef17
S.E. Hoeks, W.J.M. Scholte op Reimer, H.F. Lingsma, Y. van Gestel, H. van Urk, J.J. Bax, M.L. Simoons, D. Poldermans. (2010) Process of Care Partly Explains the Variation in Mortality Between Hospitals After Peripheral Vascular Surgery. European Journal of Vascular and Endovascular Surgery 40:2, 147-154
CrossRef18
P. N. Post, M. Kuijpers, T. Ebels, F. Zijlstra. (2010) The relation between volume and outcome of coronary interventions: a systematic review and meta-analysis. European Heart Journal
CrossRef19
Michael T. Cudnik, Robert H. Schmicker, Christian Vaillancourt, Craig D. Newgard, James M. Christenson, Daniel P. Davis, Robert A. Lowe. (2010) A geospatial assessment of transport distance and survival to discharge in out of hospital cardiac arrest patients: Implications for resuscitation centers. Resuscitation 81:5, 518-523
CrossRef20
Ching-Chih Lee, Hsu-Chueh Ho, Pesus Chou. (2010) Multivariate analyses to assess the effect of surgeon volume on survival rate in oral cancer: A nationwide population-based study in Taiwan. Oral Oncology 46:4, 271-275
CrossRef21
Ross, Joseph S., Normand, Sharon-Lise T., Wang, Yun, Ko, Dennis T., Chen, Jersey, Drye, Elizabeth E., Keenan, Patricia S., Lichtman, Judith H., Bueno, Héctor, Schreiner, Geoffrey C., Krumholz, Harlan M., . (2010) Hospital Volume and 30-Day Mortality for Three Common Medical Conditions. New England Journal of Medicine 362:12, 1110-1118
Full Text22
L. Weißbach, C. Schaefer. (2010) Kontra Mindestmengen. best practice onkologie 5:1, 16-23
CrossRef23
Yue Li, Xueya Cai, Dana B. Mukamel, Laurent G. Glance. (2010) The Volume-Outcome Relationship in Nursing Home Care. Medical Care 48:1, 52-57
CrossRef24
Laura-Mae Baldwin, Leighton Chan, C. Holly A. Andrilla, Edwin D. Huff, L. Gary Hart. (2010) Quality of Care for Myocardial Infarction in Rural and Urban Hospitals. The Journal of Rural Health 26:1, 51-57
CrossRef25
P. N. Post, J. Wittenberg, J. S. Burgers. (2009) Do specialized centers and specialists produce better outcomes for patients with chronic diseases than primary care generalists? A systematic review. International Journal for Quality in Health Care 21:6, 387-396
CrossRef26
Bechien U. Wu. (2009) The Impact of Hospital Volume on Outcomes in Acute Pancreatitis: A Case for Centers of Excellence?. Gastroenterology 137:6, 1886-1888
CrossRef27
Anand Singla, Jessica Simons, YouFu Li, Nicholas G. Csikesz, Sing Chau Ng, Jennifer F. Tseng, Shimul A. Shah. (2009) Admission Volume Determines Outcome for Patients With Acute Pancreatitis. Gastroenterology 137:6, 1995-2001
CrossRef28
W.K. Nicholson, F. Witter, N.R. Powe. (2009) Effect of Hospital Setting and Volume on Clinical Outcomes in Women with Gestational and Type 2 Diabetes Mellitus. Journal of Women's Health 18:10, 1567-1576
CrossRef29
Anand Singla, Nicholas G. Csikesz, Jessica P. Simons, You Fu Li, Sing Chau Ng, Jennifer F. Tseng, Shimul A. Shah. (2009) National hospital volume in acute pancreatitis: analysis of the Nationwide Inpatient Sample 1998-2006. HPB 11:5, 391-397
CrossRef30
Guy David, Tanguy Brachet. (2009) Retention, Learning by Doing, and Performance in Emergency Medical Services. Health Services Research 44:3, 902-925
CrossRef31
Herng-Ching Lin, Chien-Heng Chu, Hsin-Chien Lee. (2009) Physician volume, physician specialty and in-hospital mortality for patients with acute myocardial infarction. International Journal of Cardiology 134:2, 288-290
CrossRef32
Michelle L. Mayer, Heather A. Beil, Daniel von Allmen. (2009) Distance to care and relative supply among pediatric surgical subspecialties. Journal of Pediatric Surgery 44:3, 483-495
CrossRef33
J.O.J. Peels, R.W.M. Hautvast, J.B.R.M. de Swart, M.A.J.M. Huybregts, V.A.W.M. Umans, A.E.R. Arnold, G.A.J. Jessurun, F. Zijlstra. (2009) Percutaneous coronary intervention without on site surgical back-up; two-years registry of a large Dutch community hospital. International Journal of Cardiology 132:1, 59-65
CrossRef34
John Kao, Ricardo Vicuna, John A. House, John S. Rumsfeld, Henry H. Ting, John A. Spertus. (2008) Disparity in drug-eluting stent utilization by insurance type. American Heart Journal 156:6, 1133-1140
CrossRef35
Ashwin N. Ananthakrishnan, Emily L. McGinley, David G. Binion. (2008) Does It Matter Where You Are Hospitalized for Inflammatory Bowel Disease? A Nationwide Analysis of Hospital Volume. The American Journal of Gastroenterology 103:11, 2789-2798
CrossRef36
Claudio Jeldres, Nazareno Suardi, Fred Saad, Francesco Montorsi, Shahrokh F. Shariat, Paul Perrotte, Naeem Bhojani, Jochen Walz, Georg C. Hutterer, Markus Graefen, Luc Valiquette, Pierre I. Karakiewicz. (2008) High Provider Volume is Associated with Lower Rate of Secondary Therapies after Definitive Radiotherapy for Localized Prostate Cancer. European Urology 54:1, 97-106
CrossRef37
Alf Inge Larsen, Tor H. Melberg, Vernon Bonarjee, Ståle Barvik, Dennis W.T. Nilsen. (2008) Change to a primary PCI program increases number of patients offered reperfusion therapy and significantly reduces mortality. International Journal of Cardiology 127:2, 208-213
CrossRef38
Jie Wang. (2008) Characteristics of coronary arteriography and traditional Chinese medicine syndrome of 1 069 patients with coronary artery disease. Journal of Chinese Integrative Medicine 6:2, 148-152
CrossRef39
Hsin-Chien Lee, Herng-Ching Lin. (2007) Is the volume-outcome relationship sustained in psychiatric care?. Social Psychiatry and Psychiatric Epidemiology 42:8, 669-672
CrossRef40
Nina Shervin, Harry E Rubash, Jeffrey N Katz. (2007) Orthopaedic Procedure Volume and Patient Outcomes. Clinical Orthopaedics and Related Research 457, 35-41
CrossRef41
M. M. Chowdhury, H. Dagash, A. Pierro. (2007) A systematic review of the impact of volume of surgery and specialization on patient outcome. British Journal of Surgery 94:2, 145-161
CrossRef42
C DORO, J DIMICK, R WAINESS, G UPCHURCH, A URQUHART. (2006) Hospital Volume and Inpatient Mortality Outcomes of Total Hip Arthroplasty in the United States. The Journal of Arthroplasty 21:6, 10-16
CrossRef43
Kahn, Jeremy M., Goss, Christopher H., Heagerty, Patrick J., Kramer, Andrew A., O'Brien, Chelsea R., Rubenfeld, Gordon D., . (2006) Hospital Volume and the Outcomes of Mechanical Ventilation. New England Journal of Medicine 355:1, 41-50
Full Text44
Timothy D. Henry, James M. Atkins, Michael S. Cunningham, Gary S. Francis, William J. Groh, Robert A. Hong, Karl B. Kern, David M. Larson, Erik Magnus Ohman, Joseph P. Ornato, Mary Ann Peberdy, Michael J. Rosenberg, W. Douglas Weaver. (2006) ST-Segment Elevation Myocardial Infarction: Recommendations on Triage of Patients to Heart Attack Centers. Journal of the American College of Cardiology 47:7, 1339-1345
CrossRef45
Neil Hanlon, Chris Skedgel. (2006) Cross-district utilization of general hospital care in Nova Scotia: Policy and service delivery implications for rural districts. Social Science & Medicine 62:1, 145-156
CrossRef46
C. Müller-Mai, U. Schulze-Raestrup, A. Ekkernkamp, R. Smektala. (2006) Frühkomplikationen nach Versorgung der Schenkelhalsfraktur. Der Chirurg 77:1, 61-69
CrossRef47
Brahmajee K. Nallamothu, Kim A. Eagle, Victor A. Ferraris, Robert M. Sade. (2005) Should Coronary Artery Bypass Grafting Be Regionalized?. The Annals of Thoracic Surgery 80:5, 1572-1581
CrossRef48
S??ren Rasmussen, Ann-Dorthe O. Zwisler, Steen Z. Abildstrom, Jan K. Madsen, Mette Madsen. (2005) Hospital Variation in Mortality After First Acute Myocardial Infarction in Denmark From 1995 to 2002. Medical Care 43:10, 970-978
CrossRef49
J. Turumbay, C. Moreno-Iribas, J.R. Carmona, E. Alegría, I. Ezpeleta, A. Manrique. (2005) Diferencias en el manejo del infarto agudo de miocardio según la edad en los hospitales de Navarra. Estudio IBERICA. Revista Española de Geriatría y Gerontología 40:4, 205-213
CrossRef50
Jonathan M. Samet, Leon Gordis. 2005. Epidemiology, Overview. .
CrossRef51
George M Tadros, Elias A Iliadis, Robert F Wilson, Timothy D Henry. (2005) The evolving role of rescue therapy for acute myocardial infarction. Future Cardiology 1:4, 473-478
CrossRef52
(2005) Guías de Práctica Clínica sobre intervencionismo coronario percutáneo. Revista Española de Cardiología 58:6, 679-728
CrossRef53
Jeffrey N. Katz, Karen Costenbader, Daniel H. Solomon, Elena Losina. (2005) Does practice make perfect?. Arthritis & Rheumatism 52:6, 1628-1631
CrossRef54
David M. Larson, Scott W. Sharkey, Barbara T. Unger, Timothy D. Henry. (2005) Implementation of Acute Myocardial Infarction Guidelines in Community Hospitals. Academic Emergency Medicine 12:6, 522-527
CrossRef55
A. Dibra, A. Kastrati, H. Sch
hlen, A. Sch
CrossRef56
Mary Beth Landrum, Edward Guadagnoli, Rose Zummo, David Chin, Barbara J. McNeil. (2004) Care following Acute Myocardial Infarction in the Veterans Administration Medical Centers: A Comparison with Medicare. Health Services Research 39:6p1, 1773-1792
CrossRef57
Elena Losina, Jane Barrett, John A. Baron, Matthew Levy, Charlotte B. Phillips, Jeffrey N. Katz. (2004) Utilization of low-volume hospitals for total hip replacement. Arthritis & Rheumatism 51:5, 836-842
CrossRef58
Philippe P. Hujoel. (2004) Endpoints in periodontal trials: the need for an evidence-based research approach. Periodontology 2000 36:1, 196-204
CrossRef59
P SHARKEY. (2004) Relationship between surgical volume and early outcomes of total hip arthroplastyDo results continue to get better?1. The Journal of Arthroplasty 19:6, 694-699
CrossRef60
Kristin Madison. (2004) Multihospital System Membership and Patient Treatments, Expenditures, and Outcomes. Health Services Research 39:4p1, 749-770
CrossRef61
Elizabeth H. Bradley, Jeph Herrin, Jennifer A. Mattera, Eric S. Holmboe, Yongfei Wang, Paul Frederick, Sarah A. Roumanis, Martha J. Radford, Harlan M. Krumholz. (2004) Hospital-Level Performance Improvement. Medical Care 42:6, 591-599
CrossRef62
Laura-Mae Baldwin, Richard F. MacLehose, L. Gary Hart, Shelli K. Beaver, Nathan Every, Leighton Chan. (2004) Quality of Care for Acute Myocardial Infarction in Rural and Urban US Hospitals. The Journal of Rural Health 20:2, 99-108
CrossRef63
Sharina D. Person, Jeroan J. Allison, Catarina I. Kiefe, Michael T. Weaver, O. Dale Williams, Robert M. Centor, Norman W. Weissman. (2004) Nurse Staffing and Mortality for Medicare Patients with Acute Myocardial Infarction. Medical Care 42:1, 4-12
CrossRef64
Afschin Gandjour, Angelika Bannenberg, Karl W. Lauterbach. (2003) Threshold Volumes Associated With Higher Survival in Health Care. Medical Care 41:10, 1129-1141
CrossRef65
Kazim Sheikh. (2003) Reliability of Provider Volume and Outcome Associations for Healthcare Policy. Medical Care 41:10, 1111-1117
CrossRef66
David W. Baker, Doug Einstadter, Charles Thomas, Scott Husak, Nahida H. Gordon, Randall D. Cebul. (2003) The Effect of Publicly Reporting Hospital Performance on Market Share and Risk-Adjusted Mortality at High-Mortality Hospitals. Medical Care 41:6, 729-740
CrossRef67
Petersen, Laura A., Normand, Sharon-Lise T., Leape, Lucian L., McNeil, Barbara J., . (2003) Regionalization and the Underuse of Angiography in the Veterans Affairs Health Care System as Compared with a Fee-for-Service System. New England Journal of Medicine 348:22, 2209-2217
Full Text68
Javed Butler, Joseph P. Weingarten, Judith A. Weddle, Manoj K. Jain. (2003) Differences Among Hospitals in Delivery of Care for Heart Failure. Journal for Healthcare Quality 25:3, 4-39
CrossRef69
John F Thompson, Helen M Shaw, Jonathan R Stretch, William H McCarthy, Gerald W Milton. (2003) The Sydney Melanoma Unit—a multidisciplinary melanoma treatment center. Surgical Clinics of North America 83:2, 431-451
CrossRef70
David M Shahian, Sharon-Lise T Normand. (2003) The volume-outcome relationship: from Luft to Leapfrog. The Annals of Thoracic Surgery 75:3, 1048-1058
CrossRef71
Laura A. Petersen, Sharon-Lise T. Normand, Benjamin G. Druss, Robert A. Rosenheck. (2003) Process of Care and Outcome after Acute Myocardial Infarction for Patients with Mental Illness in the VA Health Care System: Are There Disparities?. Health Services Research 38:1p1, 41-63
CrossRef72
Nandini Dendukuri, Sharon-Lise T. Normand, Barbara J. McNeil. (2003) Impact of Cardiac Service Availability on Case-Selection for Angiography and Survival Associated with Angiography. Health Services Research 38:1p1, 21-40
CrossRef73
Ian A Scott. (2003) Determinants of Quality of In-Hospital Care for Patients with Acute Coronary Syndromes. Disease Management & Health Outcomes 11:12, 801-816
CrossRef74
Ayanian, John Z., Landrum, Mary Beth, Guadagnoli, Edward, Gaccione, Peter, . (2002) Specialty of Ambulatory Care Physicians and Mortality among Elderly Patients after Myocardial Infarction. New England Journal of Medicine 347:21, 1678-1686
Full Text75
Benjamin M. Scirica, Christopher P. Cannon, Michael C. Gibson, Sabina A. Murphy, David J. Moliterno, Vernon H. Anderson, Frank V. Aguirre, Christopher B. Granger, Costas T. Lambrew, LeRoy E. Rabbani, Shelly K. Sapp, Joan E. Booth, James J. Ferguson, Eugene Braunwald. (2002) Assessing the Effect of Publication of Clinical Guidelines on the Management of Unstable Angina and Non-ST Elevation Myocardial Infarction in The TIMI III (1990-1993) and the GUARANTEE (1995-1996) Registries. Critical Pathways in Cardiology: A Journal of Evidence-Based Medicine 1:3, 150-158
CrossRef76
Benjamin M. Scirica, Christopher P. Cannon, C. Michael Gibson, Sabina A. Murphy, David J. Moliterno, H. Vernon Anderson, Frank V. Aguirre, Christopher B. Granger, Costas T. Lambrew, LeRoy E. Rabbani, Shelly K. Sapp, Joan E. Booth, James J. Ferguson, Eugene Braunwald. (2002) Assessing the Effect of Publication of Clinical Guidelines on the Management of Unstable Angina and Non-ST Elevation Myocardial Infarction in The TIMI III (1990???1993) and the GUARANTEE (1995???1996) Registries. Critical Pathways in Cardiology: A Journal of Evidence-Based Medicine 1:3, 150-158
CrossRef77
Daniel H. Solomon, Elena Losina, John A. Baron, Anne H. Fossel, Edward Guadagnoli, Elizabeth A. Lingard, Andrew Miner, Charlotte B. Phillips, Jeffrey N. Katz. (2002) Contribution of hospital characteristics to the volume-outcome relationship: Dislocation and infection following total hip replacement surgery. Arthritis & Rheumatism 46:9, 2436-2444
CrossRef78
Rajendra H Mehta, Douglas A Criger, Christopher B Granger, Karen K Pieper, Robert M Califf, Eric J Topol, Eric R Bates. (2002) Patient outcomes after fibrinolytic therapy for acute myocardial infarction at hospitals with and without coronary revascularization capability. Journal of the American College of Cardiology 40:6, 1034-1040
CrossRef79
Vladimir Džavík, Jean-L.uçien Rouleau. (2002) Should all patients with an acute myocardial infarction present to a hospital with revascularization capabilities?. Journal of the American College of Cardiology 40:6, 1041-1043
CrossRef80
Mandeep Singh, Henry H Ting, Peter B Berger, Kirk N Garratt, David R Holmes, Bernard J Gersh. (2002) Rationale for on-site cardiac surgery for primary angioplasty: a time for reappraisal. Journal of the American College of Cardiology 39:12, 1881-1889
CrossRef81
Monica E. Kleinman. (2002) Clinical practice parameters for pediatric and neonatal septic shock: To have or to have not? *. Critical Care Medicine 30:6, 1400-1401
CrossRef82
David R Thiemann. (2002) Primary angioplasty for elderly patients with myocardial infarction. Journal of the American College of Cardiology 39:11, 1729-1732
CrossRef83
D.A Alter, C.D Naylor, P.C Austin, J.V Tu. (2002) Biology or bias: practice patterns and long-term outcomes for men and women with acute myocardial infarction. Journal of the American College of Cardiology 39:12, 1909-1916
CrossRef84
Susan E. Bronskill, Sharon-Lise T. Normand, Mary Beth Landrum, Robert A. Rosenheck. (2002) Longitudinal profiles of health care providers. Statistics in Medicine 21:8, 1067-1088
CrossRef85
David Heimbach. (2002) What’s new in general surgery: burns and metabolism. Journal of the American College of Surgeons 194:2, 156-164
CrossRef86
Michael Hermann, Gunter Alk, Rudolf Roka, Karl Glaser, Michael Freissmuth. (2002) Laryngeal Recurrent Nerve Injury in Surgery for Benign Thyroid Diseases. Annals of Surgery 235:2, 261-268
CrossRef87
Roger A. Rosenblatt. (2002) Quality of Care in the Rural Context: A Proposed Research Agenda. The Journal of Rural Health 18:5, 176-185
CrossRef88
Michael J. Solomon, Robert J. Thomas, Melina Gattellari, Jeanette E. Ward. (2001) Does type of surgeon matter in rectal cancer surgery? Evidence, guideline consensus and surgeons' views. ANZ Journal of Surgery 71:12, 711-714
CrossRef89
Sherman T. Folland, Richard A. Hofler. (2001) How reliable are hospital efficiency estimates? Exploiting the dual to homothetic production. Health Economics 10:8, 683-698
CrossRef90
McNeil, Barbara J., . (2001) Hidden Barriers to Improvement in the Quality of Care. New England Journal of Medicine 345:22, 1612-1620
Full Text91
S. J. Nicholls, P. McElduff, A. J. Dobson, K. D. Jamrozik, M. S. T. Hobbs, J. W. Leitch. (2001) Underuse of beta-blockers following myocardial infarction: a tale of two cities. Internal Medicine Journal 31:7, 391-396
CrossRef92
Halm, Ethan A., Chassin, Mark R., . (2001) Why Do Hospital Death Rates Vary?. New England Journal of Medicine 345:9, 692-694
Full Text93
Bach, Peter B., Cramer, Laura D., Schrag, Deborah, Downey, Robert J., Gelfand, Sarah E., Begg, Colin B., . (2001) The Influence of Hospital Volume on Survival after Resection for Lung Cancer. New England Journal of Medicine 345:3, 181-188
Full Text94
John M. Westfall, Joe McGloin. (2001) Impact of Double Counting and Transfer Bias on Estimated Rates and Outcomes of Acute Myocardial Infarction. Medical Care 39:5, 459-468
CrossRef95
Claresa S. Levetan. (2001) The Value of the Clinical Endocrinologist in the New Millennium. The Endocrinologist 11:2, 137-145
CrossRef96
Jane H. Brice, Terence Valenzuela, Joseph P. Ornato, Robert A. Swor, Jerry Overton, Ronald G. Pirrallo, James Dunford, Robert M. Domeier. (2001) O PTIMAL P REHOSPITAL C ARDIOVASCULAR C ARE. Prehospital Emergency Care 5:1, 65-72
CrossRef97
James E. Pointer. (2001) E XPERIENCE AND M ENTORING R EQUIREMENTS FOR C OMPETENCE IN N EW /I NEXPERIENCED P ARAMEDICS. Prehospital Emergency Care 5:4, 379-383
CrossRef98
Andrew D Auerbach, Mary Beth Hamel, Robert M Califf, Roger B Davis, Neil S Wenger, Norman Desbiens, Lee Goldman, Humberto Vidaillet, Alfred F Connors, Joanne Lynn, Neal V Dawson, Russell S Phillips. (2000) Patient characteristics associated with care by a cardiologist among adults hospitalized with severe congestive heart failure. Journal of the American College of Cardiology 36:7, 2119-2125
CrossRef99
Guadagnoli, Edward, Landrum, Mary Beth, Peterson, Eric A., Gahart, Martin T., Ryan, Thomas J., McNeil, Barbara J., . (2000) Appropriateness of Coronary Angiography after Myocardial Infarction among Medicare Beneficiaries — Managed Care versus Fee for Service. New England Journal of Medicine 343:20, 1460-1466
Full Text100
Donald J. Willison, Stephen B. Soumerai, R. Heather Palmer. (2000) Association of Physician and Hospital Volume With Use of Aspirin and Reperfusion Therapy in Acute Myocardial Infarction. Medical Care 38:11, 1092-1102
CrossRef101
Cheuk-Kit Wong, Harvey D. White. (2000) Medical treatment for acute coronary syndromes. Current Opinion in Cardiology 15:6, 441-462
CrossRef102
Canto, John G., Every, Nathan R., Magid, David J., Rogers, William J., Malmgren, Judith A., Frederick, Paul D., French, William J., Tiefenbrunn, Alan J., Misra, Vijay K., Kiefe, Catarina I., Barron, Hal V., . (2000) The Volume of Primary Angioplasty Procedures and Survival after Acute Myocardial Infarction. New England Journal of Medicine 342:21, 1573-1580
Full Text103
Francesco Frassoni, Myriam Labopin, Ray Powles, Jean-Yves Mary, William Arcese, Andrea Bacigalupo, Donald Bunjes, Eliane Gluckman, Tapani Ruutu, Ulrich W Schaefer, Jorge Sierra, Jean Paul Vernant, Roel Willemze, Theo de Witte, Norbert Claude Gorin Transplantation. (2000) Effect of centre on outcome of bone-marrow transplantation for acute myeloid leukaemia. The Lancet 355:9213, 1393-1398
CrossRef104
Gordon A Ewy, Joseph P Ornato. (2000) Emergency cardiac care: introduction. Journal of the American College of Cardiology 35:4, 825-880
CrossRef105
Amy C. Edmondson, Richard M. Bohmer, Gary P. Pisano. 2000. Learning new technical and interpersonal routines in operating room teams The case of minimally invasive cardiac surgery. , 29-51.
CrossRef106
Alter, David A., Naylor, C. David, Austin, Peter, Tu, Jack V., . (1999) Effects of Socioeconomic Status on Access to Invasive Cardiac Procedures and on Mortality after Acute Myocardial Infarction. New England Journal of Medicine 341:18, 1359-1367
Full Text107
(1999) The Relation between Volume and Outcome in Health Care. New England Journal of Medicine 341:14, 1085-1086
Full Text108
Hannan, Edward L., . (1999) The Relation between Volume and Outcome in Health Care. New England Journal of Medicine 340:21, 1677-1679
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