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(Circulation. 2007;116:1925-1930.)
© 2007 American Heart Association, Inc.
Health Services and Outcomes Research |
From the Section of Chronic Disease Epidemiology, Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, Conn (J.H.L., N.B.A.); Mid America Heart Institute of St Lukes Hospital, Kansas City, Mo (J.A.S., K.J.R.); University of Missouri, Kansas City (J.A.S.); Division of Cardiology, Department of Medicine, New York University Medical Center, New York (M.J.R.); Denver Veterans Affairs Medical Center, Denver, Colo (J.S.R.); Department of Medicine, Denver Health Medical Center, and the Department of Medicine and Colorado Health Outcomes Program, University of Colorado at Denver and Health Sciences Center, Denver (F.A.M.); Christiana Care Health System, Newark, Del, and the Department of Medicine, Jefferson University, Philadelphia, Pa (W.S.W.); and Section of Cardiovascular Medicine and the Robert Wood Johnson Clinical Scholars Program, Department of Medicine; Section of Health Policy and Administration, Department of Epidemiology and Public Health, Yale University School of Medicine; and the Center for Outcomes Research and Evaluation, Yale-New Haven Hospital, New Haven, Conn (H.M.K.).
Correspondence to Harlan M. Krumholz, MD, SM, 333 Cedar St, Room I-456 SHM, PO Box 208088, New Haven, CT 06520.8088. E-mail harlan.krumholz{at}yale.edu
Received June 15, 2007; accepted August 28, 2007.
| Abstract |
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Methods and Results— A total of 3907 patients admitted with an acute myocardial infarction were prospectively enrolled in 19 US centers between January 2003 and June 2004. Acute noncardiac conditions present at admission with imminent threat to life were identified from medical record review within 24 hours of admission. Using multivariable analyses, we evaluated the relationship between these conditions and in-hospital mortality. We documented a concomitant acute, severe, noncardiac condition in 6.8% (n=267) of the study sample. The most common concomitant conditions were severe pneumonia (potentially requiring intubation; 18.4%), severe gastrointestinal bleeding/anemia (15.7%), stroke (9.7%), and sepsis (9.4%). These patients were less likely to be ideal for or to receive evidence-based therapies at the time of admission. The in-hospital mortality was 21.3% (57 of 267) for patients with concomitant conditions versus 2.7% (100 of 3640) for those without these conditions. The presence of an acute noncardiac condition was associated with an increased risk of in-hospital mortality after adjustment for demographic and clinical characteristics and disease severity (odds ratio, 5.0; 95% confidence interval, 3.3 to 7.7).
Conclusions— Concomitant, acute, noncardiac conditions are common and associated with a marked increase in the risk of in-hospital mortality.
Key Words: comorbidity mortality myocardial infarction prognosis
| Introduction |
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Clinical Perspective p 1930
A single-center, retrospective study by our group reported that 1 in 12 patients admitted with AMI had an acute concomitant condition and that these patients had a much higher risk of death.9 To extend these limited observations, we designed a prospective, multicenter, cohort study within the Prospective Registry Evaluating Myocardial Infarction: Event and Recovery, Quality Improvement (PREMIER-QI) study12 to specifically characterize the prevalence and prognostic importance of acute, severe, concomitant noncardiac conditions on the care and outcomes of patients with AMI. In PREMIER-QI, the medical records of all patients at the participating sites who were admitted with an AMI were reviewed to determine the presence of an acute, severe, noncardiac condition that was life threatening even in the absence of the AMI and the association of these conditions with patient outcomes.
| Methods |
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18 years of age and had other evidence supporting the diagnosis of AMI such as prolonged (>20 minutes) ischemic signs/symptoms or ECG ST changes. Patients not presenting initially to the enrolling institution were eligible only if they were transferred within the first 24 hours of initial presentation. Patients who were incarcerated and those having elevated cardiac markers as a complication of elective coronary revascularization were not eligible. Institutional Research Board approval was obtained at each participating institution, and patients signed informed consent for baseline and follow-up interviews.
Data Collection
We used 2 sources of baseline data in this study. First, trained data collectors performed chart abstraction of data on patients presentation, clinical history, admission medications, presenting ECG, and treatments during the first 24 hours. Second, at discharge, patients diagnostic information, including the results of angiography and ECG, and information on in-hospital treatment, in-hospital complications, in-hospital mortality, and final diagnosis were collected. For practical reasons, the final chart abstractions were performed after discharge so that final discharge summaries and dictations were completed.
Acute Noncardiac Conditions
We abstracted acute noncardiac conditions at the patients time of arrival using a standardized method from each patients medical record during the first 24 hours. The specific question was, "Did the patient have any other acute noncardiac conditions at the time of arrival that were potentially life threatening?" If yes, we documented the condition and classified it by the following prespecified categories: severe pneumonia potentially requiring intubation, trauma, stroke, severe gastrointestinal bleeding/anemia, sepsis, hip fracture, or other conditions. We selected a subset of cases with potentially life-threatening conditions and asked the local principal investigators to conduct a second chart review to verify the presence and severity of these acute potentially life-threatening conditions at the time of admission.
Additional Variables
We collected medical record abstraction of patients presentation, clinical comorbidities, presenting ECG, diagnostic information (including the results of angiography), in-hospital treatment, complications (bleeding included cardiac catheterization site, coronary artery bypass graft surgery [CABG] surgical site, other instrumented site, gastrointestinal, or other), and final diagnoses (Tables 1 through 3![]()
). Eligibility for short-term therapies, including aspirin or β-blocker therapy within 24 hours, and reperfusion (fibrinolytic therapy within 30 minutes or primary percutaneous coronary intervention [PCI] within 2 hours) was determined on the basis of Centers for Medicare and Medicaid Services and the Joint Commission National Hospital Quality Measure definitions.15 Common exclusions included patients who were transferred from another acute-care hospital on the day of arrival, those who left against medical advice, and those on comfort measures only. Additional exclusions for aspirin included active bleeding, aspirin allergy, Coumadin or warfarin as prearrival medication, or other reasons documented by a care provider for not giving aspirin within 24 hours of arrival. Exclusions for β-blockers within 24 hours included β-blocker allergy, bradycardia, heart failure, second- or third-degree heart block, shock on arrival or within 24 hours of arrival, or other reasons documented by the care provider. Exclusions for primary PCI included patients administered fibrinolytic therapy. We defined left ventricular systolic dysfunction as a recorded left ventricular ejection fraction <40% or documented left ventricular systolic dysfunction graded as severe or moderate.
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Outcome
The outcome of this study was in-hospital mortality. We obtained mortality data from chart review and by cross-referencing patients social security numbers with the Social Security Death Master File.
Statistical Analysis
We used bivariate analyses to examine the relationship between the acute noncardiac conditions and demographic factors, clinical presentation, patterns of care, and initial treatment. We analyzed categorical variables using Fishers exact or
2 test, and continuous variables using the t test or the Kruskal-Wallis test, depending on the distribution of the variable. A logistic regression model examined the relationship between acute noncardiac conditions and in-hospital mortality, with adjustment for site, patient demographic factors (age, gender, race), medical history (prior AMI, angina, heart failure, prior CABG or PCI, stroke, diabetes mellitus, hypertension, hypercholesterolemia, smoking status), and clinical characteristics (new chest pain, acute systolic blood pressure, acute heart rate, ST elevation, ST depression, Q wave, left bundle-branch block, right bundle-branch block, anterior AMI, left ventricular ejection fraction <40%). To minimize the concern that patients with heart failure could be misclassified as having pneumonia or sepsis, we repeated our analyses after excluding pneumonia and sepsis as acute noncardiac conditions. Age was modeled using restricted cubic splines to account for a possible nonlinear relationship. Information on
1 covariates was missing for 308 patients (8%); 77 patients (2%) were missing >1 value. Missing covariate data were assumed to be missing at random (ie, noninformatively missing given the available observed data) and were imputed using multiple imputation methods to allow incorporation of all patients and to correctly account for uncertainty resulting from absent data. The imputation model consisted of all variables used in the multivariable model plus additional clinical information. We performed all statistical analyses using the SAS statistical package version 9.1 (SAS Institute, Inc, Cary, NC).
The authors had full access to and take full responsibility for the integrity of the data. All authors have read and agree to the manuscript as written.
| Results |
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Clinical Presentation
The clinical presentation of the AMI differed in patients admitted with an acute noncardiac condition compared with patients who did not present with one of these conditions (Table 2). A greater percentage of patients with acute noncardiac conditions had elevated heart rate, hypotension, and elevated serum creatinine on presentation (P<0.001). These patients also had a lower likelihood of ST-segment elevation on their ECG (P<0.001) and were less likely to have ischemic symptoms documented at the time of presentation (P<0.001).
Treatment Patterns
Treatment patterns varied between groups. Patients with acute noncardiac conditions were less likely to be considered ideal for short-term (<24 hours) therapies such as aspirin, β-blockers, and timely reperfusion (P<0.001; Table 3). Even among ideal candidates, however, patients with acute noncardiac conditions were less likely to receive these therapies (P<0.001). Additional initial therapies such as antiplatelet agents (clopidogrel or ticlopidine), fibrinolytic therapy, antithrombin, or glycoprotein IIb/IIIa inhibitor (P<0.001) also were used less often among these patients. Patients with acute noncardiac conditions had lower rates of coronary angiography, primary PCI, nonacute PCI, or CABG (P<0.001).
Adverse Events
Adverse clinical events during the hospitalization occurred more frequently for patients who presented with concomitant acute noncardiac conditions at admission (Table 3). Rates of bleeding, cardiac arrest, cardiogenic shock, and heart failure (P<0.001) all were higher for patients with acute noncardiac conditions. The median length of stay was almost twice as long for patients who presented with an acute noncardiac condition (7.5 days [interquartile range, 4 to 12 days] versus 4.0 [interquartile range, 3 to 6 days]; Kruskal-Wallis P<0.001), and in-hospital mortality was markedly higher (21.3%) compared with that for patients without such conditions (2.7%; P<0.001).
Risk-Adjusted Analyses
A risk-adjusted model was developed to examine the independent association between acute noncardiac conditions at admission and in-hospital mortality, with adjustment for demographic, clinical, and treatment variables. In an unadjusted model, odds of in-hospital mortality were 9-fold higher for patients who presented with an acute noncardiac condition at admission compared with patients who did not have such conditions (odds ratio, 9.6; 95% confidence interval, 6.7 to 13.7). The association was attenuated but persisted after adjustment for site, demographic characteristics, medical history, and clinical characteristics (odds ratio, 5.0; 95% confidence interval, 3.3 to 7.7). The risk-adjusted association remained unchanged in the model that included imputed values for the missing data elements (odds ratio, 5.0; 95% confidence interval, 3.4 to 7.5). To minimize the concern that patients with heart failure could be misclassified as having pneumonia or sepsis, we repeated our analyses after excluding pneumonia and sepsis as acute noncardiac conditions and found no difference in the association between acute noncardiac conditions and outcome.
| Discussion |
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In the present study, we have identified a subgroup of patients with AMI who require physicians to manage multiple acute conditions. Current clinical guidelines for AMI do not address the clinical management of these complex patients largely because the literature addressing this group is so limited. Much attention has been directed toward the prevalence and prognostic importance of chronic comorbid conditions, but acute severe conditions have been neglected. Moreover, these acute conditions have typically not been included in risk stratification and risk adjustment models, nor has their prognostic role on outcomes been assessed.2–8,16–22
In our prior single-site, retrospective study, we found that 9% of patients with AMI presented with a concomitant, potentially life-threatening, noncardiac condition that was associated with double the odds of dying in the hospital.9 We further reported that patients who presented with serious, nonacute conditions (1 in 5 AMI patients) did not have this increased risk of dying. Using a prospective, multicenter design, the present study confirms that a substantial subset of AMI patients present with an acute concomitant condition that is associated with increased mortality in the hospital. The comparability of prevalence rates and marked increase in mortality after risk adjustment for other covariates show the prognostic importance of acute, severe, noncardiac conditions on patient outcomes.
This study highlights the complexity of many patients with AMI. The patients with acute, severe, concomitant conditions are unlikely to meet eligibility for a randomized trial, and even if they meet criteria, it is unlikely that they will be enrolled.4,8,16,18,19,21,22 Similarly, nonclinical trial studies, including cohort studies, registries, or administrative data sets, have not described these conditions in terms of their acute presentation or severity at the time of the AMI.2,4–7,16,23 Thus, little evidence exists to guide the treatment of these patients. The findings from this study indicate the importance of acknowledging the presence of these patients and developing evidence to help clinicians care for them. As we have shown, the presence of these conditions influences the initial presentation, use of appropriate short-term therapies, and outcomes of AMI patients. Our study demonstrates the feasibility of capturing clinical information on acute potentially life-threatening conditions that are present within the context of an AMI admission. Data elements that capture acute severe conditions could be incorporated into other prospective AMI surveillance studies. The development of measures and data collection strategies that include the severity of acute conditions will improve our ability to test how these concurrent conditions influence the care and outcomes of patients and, importantly, will expand our knowledge base to develop more appropriate clinical guidelines for these complex patients.
Several issues must be considered in the interpretation of this study. We used information abstracted from medical records to identify our subgroup of AMI patients with active concomitant conditions at admission. It is possible that some important clinical events were not recorded in the medical chart; however, misclassification of patients should bias our findings to the null hypothesis, and our data collection clearly identified a cohort with adverse outcomes. Our ability to discriminate between acute conditions and chronic conditions was increased by a 2-stage record abstraction process for the PREMIER-QI project. Acute noncardiac events at admission were captured by record abstraction within the first 24 hours of the admission. This strategy guaranteed that complications that occurred during the hospitalization would not be identified as acute conditions present on admission. The length of stay was greater for patients with acute noncardiac conditions, thus introducing more opportunity to detect mortality; however, the mean and median days from admission to death were relatively similar for patients with and without these conditions (11 and 9 mean days, 7 and 6 median days, respectively). Finally, although the 19 PREMIER sites were selected to represent a spectrum of healthcare settings, including not-for-profit, government, academic, and nonacademic institutions, we did not include smaller, rural hospitals, and the prevalence of these factors may vary across diverse clinical settings.
Results from this multicenter study confirm that a considerable proportion of AMI patients present to the hospital with an additional acute noncardiac condition. The associated risk of mortality is exceptionally high for these patients, yet current clinical guidelines provide limited insight into the specific needs of this high-risk population. Given the disproportionate mortality associated with the dual presentation of an acute AMI and a severe, concomitant noncardiac condition, this subset of AMI patients warrants further investigation. The lack of clinical evidence about the characteristics, care, and outcomes of these high-risk AMI patients limits our ability to identify opportunities to improve their clinical management.
| Appendix |
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| Acknowledgments |
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Dr Lichtman is supported by grant K01 DP000085–03 from the Centers for Disease Control and Prevention, Atlanta, Ga. This work was funded by grants from Cardiovascular Therapeutics, Cardiovascular Outcomes, and the National Heart, Lung, and Blood Institute. The sponsors did not play a role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; or preparation, review, and approval of the manuscript.
Disclosures
None.
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| Footnotes |
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The contents of this article are solely the responsibility of the authors and do not necessarily represent the official views of the Centers for Disease Control and Prevention.
Related Article:
Circulation 2007 116: 1865.
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