Advertisement






Click here for more guidelines.
CME Topic Collections Past Issues Search Current Issue Home
     

J Am Coll Cardiol, 2005; 46:1479-1487, doi:10.1016/j.jacc.2005.05.084 (Published online 27 September 2005).
© 2005 by the American College of Cardiology Foundation
This Article
Right arrow Abstract Freely available
Right arrow Figures Only
Right arrow Full Text (PDF)
Right arrow View Online Appendix
Right arrow All Versions of this Article:
j.jacc.2005.05.084v1
46/8/1479    most recent
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Alexander, K. P.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Alexander, K. P.

CLINICAL RESEARCH: MYOCARDIAL INFARCTION

Evolution in Cardiovascular Care for Elderly Patients With Non–ST-Segment Elevation Acute Coronary Syndromes

Results From the CRUSADE National Quality Improvement Initiative

Karen P. Alexander, MD*,*, Matthew T. Roe, MD, MHS*, Anita Y. Chen, MS*, Barbara L. Lytle, MS*, Charles V. Pollack, Jr, MD, MA{dagger}, Joanne M. Foody, MD{ddagger}, William E. Boden, MD§, Sidney C. Smith, Jr, MD||, W. Brian Gibler, MD, E. Magnus Ohman, MD||, Eric D. Peterson, MD, MPH* the CRUSADE Investigators

* Duke Clinical Research Institute and Division of Cardiology, Duke University Medical Center, Durham, North Carolina
{dagger} Pennsylvania Hospital, Philadelphia, Pennsylvania
{ddagger} Section of Cardiovascular Medicine, Department of Medicine, Yale School of Medicine, New Haven, Connecticut
§ Division of Cardiology, Hartford Hospital, Hartford, Connecticut
|| Department of Cardiology, University of North Carolina, Chapel Hill, North Carolina
Department of Emergency Medicine, University of Cincinnati School of Medicine, Cincinnati, Ohio

Manuscript received March 3, 2005; revised manuscript received April 29, 2005, accepted May 3, 2005.

* Reprint requests and correspondence: Dr. Karen P. Alexander, Assistant Professor of Medicine, Duke Clinical Research Institute, Box 17969, Durham, North Carolina 27715 (Email: alexa019{at}dcri.duke.edu).


    Abstract
 Top
 Abstract
 Methods
 Results
 Discussion
 Conclusions
 References
 
OBJECTIVES: This study evaluated the impact of age on care and outcomes for non–ST-segment elevation acute coronary syndromes (NSTE ACS).

BACKGROUND: Recent clinical trials have expanded treatment options for NSTE ACS, now reflected in guidelines. Elderly patients are at highest risk, yet have previously been shown to receive less care than younger patients.

METHODS: In 56,963 patients with NSTE ACS at 443 U.S. hospitals participating in the Can Rapid Risk Stratification of Unstable Angina Patients Suppress Adverse Outcomes With Early Implementation of the American College of Cardiology/American Heart Association Guidelines (CRUSADE) National Quality Improvement Initiative from January 2001 to June 2003, we compared use of guidelines-recommended care across four age groups: <65, 65 to 74, 75 to 84, and ≥85 years. A multivariate model tested for age-related differences in treatments and outcomes after adjusting for patient, provider, and hospital factors.

RESULTS: Of the study population, 35% were ≥75 years old, and 11% were ≥85 years old. Use of acute anti-platelet and anti-thrombin therapy within the first 24 h decreased with age. Elderly patients were also less likely to undergo early catheterization or revascularization. Whereas use of many discharge medications was similar in young and old patients, clopidogrel and lipid-lowering therapy remained less commonly prescribed in elderly patients. In-hospital mortality and complication rates increased with advancing age, but those receiving more recommended therapies had lower mortality even after adjustment than those who did not.

CONCLUSIONS: Age impacts use of guidelines-recommended care for newer agents and early in-hospital care. Further improvements in outcomes for elderly patients by optimizing the safe and early use of therapies are likely.

Abbreviations and Acronyms
  ACC/AHA = American College of Cardiology/American Heart Association
  BP = blood pressure
  CHF = congestive heart failure
  CRUSADE = Can Rapid Risk Stratification of Unstable Angina Patients Suppress Adverse Outcomes With Early Implementation of the American College of Cardiology/American Heart Association Guidelines
  NSTE ACS = non–ST-segment elevation acute coronary syndromes


The optimal management of patients with acute coronary syndromes (ACS) continues to evolve rapidly with the development of new therapeutics and strategies of care. The American College of Cardiology/American Heart Association (ACC/AHA) recently updated their treatment guidelines for non–ST-segment elevation (NSTE) ACS to reflect these advancements (1,2). The guidelines emphasize the need to provide intensive and early medical and interventional therapy, particularly for those at highest risk for short-term events (3).

Prior work has shown that elderly patients with NSTE ACS are at greater risk of mortality and morbidity than younger patients, and that medication and catheter-based therapies have the greatest benefit on outcomes among patients at highest risk (4,5). Studies from the 1990s documented widespread underuse of cardiac medications in elderly populations with ST-segment elevation myocardial infarction (6–13), and many have emphasized the need for evidence-based cardiac care in all patients, particularly elderly patients (14,15). Recent efforts to increase physician awareness of age disparities and the arrival of new guidelines-recommended therapies for NSTE ACS may have altered current practice patterns for elderly ACS patients.

This analysis compares contemporary in-hospital treatment patterns and outcomes of elderly patients with NSTE ACS with their younger counterparts. We used the Can Rapid Risk Stratification of Unstable Angina Patients Suppress Adverse Outcomes With Early Implementation of the ACC/AHA Guidelines (CRUSADE) National Quality Improvement Initiative database to address this question across 443 hospitals in 46 states (16). Using this large database, we provide specific insight into the early and discharge use of medications, reported contraindications, use of an invasive strategy, and the relationship between guidelines-recommended care and mortality in young and old patients.


    Methods
 Top
 Abstract
 Methods
 Results
 Discussion
 Conclusions
 References
 
Population.   The CRUSADE initiative is an ongoing database of patients with high-risk NSTE ACS admitted to U.S. hospitals. The current analysis includes 56,963 patients who were treated at 443 hospitals between January 1, 2001, and June 30, 2003. Inclusion criteria for participation in the database were ischemic symptoms lasting ≥10 min combined with positive cardiac markers or ischemic ST-segment electrocardiograph changes (ST-segment depression or transient ST-segment elevation). Patients were ineligible for the CRUSADE initiative if they transferred into a participating hospital >24 h after the last episode of ischemic symptoms. Patients were ineligible for this analysis if they transferred out of a participating hospital resulting in incomplete data on acute care, in-hospital outcomes, and discharge therapies (n = 8,385), or had missing age information (n = 76), leaving a final population of 56,963 patients.

Data collection.   Hospitals participating in the CRUSADE initiative collect detailed process of care and in-hospital outcomes data through retrospective chart review. Data are collected anonymously during the initial hospitalization, and because no patient identifiers are collected, individual informed consent is not required. The institutional review board of each institution approves participation in the CRUSADE initiative. Data collected include the use of acute medications (within 24 h of presentation), use and timing of invasive cardiac procedures, laboratory results, physician and hospital characteristics, and discharge therapies and interventions.

Data definitions.   Charts were abstracted using specified definitions from the CRUSADE initiative data collection forms. Hypertension was defined as systolic blood pressure (BP) >140 mm Hg, diastolic BP >90 mm Hg on repeated measurements, or hypertension chronically treated with anti-hypertensive medications. Renal insufficiency was defined by serum creatine >2.0 mg/dl, creatinine clearance <30 ml/min, or need for renal dialysis. Signs of congestive heart failure (CHF) were indicated by exertional dyspnea, orthopnea, shortness of breath, labored breathing, fatigue either at rest or with exertion, rales in more than one-third of the lung fields, elevated jugular venous pressure, S3 gallop, or pulmonary congestion on X-ray believed to represent cardiac dysfunction. Hyperlipidemia was defined as total cholesterol >200 mg/dl or treatment with a lipid-lowering agent. Recurrent infarction was defined by clinical signs and symptoms of a new infarction distinct from the presenting ischemic event and meeting predefined cardiac marker and electrocardiogram criteria. Cardiogenic shock was defined by systolic BP <90 mm Hg for >1 h, not responsive to fluid resuscitation alone, and thought to be secondary to cardiac dysfunction. Transfusions were defined as any non-autologous transfusion(s) of either whole blood or packed red blood cells. The attending physician who primarily cared for the patient during the hospitalization was determined by the most frequent and consistent notations in the medical record; specialties included cardiologist, internist, family practitioner, and other.

Contraindications.   The CRUSADE initiative collects information regarding contraindications to all guidelines-recommended medications that were clinically documented in the patient's medical record. Specific clinical contraindications for given agents were as follows: aspirin (intolerance, allergy, active bleeding/history of bleeding, ulcer or serious gastrointestinal or genitourinary bleeding, dyspepsia, platelet count <100,000/mm3, anemia, use of warfarin); beta-blockers (allergy/hypersensitivity, bradycardia, heart block greater than first degree, cardiogenic shock, hypotension, chronic obstructive pulmonary disease/asthma/bronchospasm); glycoprotein IIb/IIIa inhibitors (active/recent bleeding, allergy/intolerance/hypersensitivity, platelet count <100,000/mm3, severe hypertension, recent major surgery, recent stoke/any previous hemorrhagic stroke, serum creatine >4.0 mg/dl, severe comorbid illness); heparin (active/recent bleeding, platelet count <100,000/mm3, ulcer or serious gastrointestinal or genitourinary bleeding, history of known heparin induced thrombocytopenia, severe comorbid illness); lipid-lowering agents (allergy/hypersensitivity, hepatic or renal dysfunction, abnormal liver function test results, primary biliary cirrhosis); angiotensin-converting enzyme inhibitors (allergy/intolerance, hypersensitivity, history of angioedema, impaired renal function, hypotension, hyperkalemia, pregnancy, liver disease). Importantly, beyond this pre-specified list, we allowed clinicians to document contraindications that precluded them from treating a patient. This conservative approach ensured that medication use was assessed only among patients with true eligibility for each therapy.

Outcomes.   Acute and discharge use of ACC/AHA guidelines-recommended therapies was then determined for those patients in our population who had indications but no reported contraindications for each therapy (Appendix) (1,2). We considered only those therapies receiving a class IA (evidence and/or general agreement that a given procedure or treatment is useful and effective from data derived from multiple randomized clinical trials that involved large numbers of patients) or class IB (data derived from a limited number of randomized trials that involved small numbers of patients or from careful analyses of non-randomized studies or observational registries) designation. All decisions regarding the use of medications or procedures were made by the treating physicians. We examined early use of medications, defined as those administered within 24 h of admission, and at discharge. Early medications included aspirin, clopidogrel, beta-blockers, heparin, low-molecular-weight heparin, and platelet glycoprotein IIb/IIIa inhibitors (1). Early invasive strategy, defined as cardiac catheterization within 48 h of admission, was also determined. Discharge medications included aspirin, clopidogrel, beta-blockers, angiotensin-converting enzyme inhibitors (with an ejection fraction <40%, or the presence of diabetes mellitus or hypertension), and lipid-lowering agents (with hyperlipidemia or low-density lipoprotein >100 mg/dl) per ACC/AHA guidelines recommendations (1). In-hospital clinical outcomes of interest included in-hospital mortality, myocardial infarction, CHF, recurrent stroke, revascularization, and bleeding requiring transfusion.

Analysis.   In-hospital care patterns and outcomes were compared between groups of relatively older and younger patients with NSTE ACS. We clustered patients into four age groups: <65, 65 to 74, 75 to 84, and ≥85 years old; in our analysis, young patients refers to those <65 years of age. We compared patients' baseline demographics, clinical characteristics, care patterns, and in-hospital outcomes, as well as the features of the admitting hospital. Continuous variables were reported as means with standard deviations, and categorical variables were reported as percentages. Significance was determined using chi-square tests and Kruskal-Wallis tests for categorical and continuous variables, respectively.

For medications, interventions, and in-hospital clinical outcomes, we used generalized estimating equations to adjust for patient comorbidity and provider characteristics. Generalized estimating equations provided a variant of the multiple logistic regression model, through which we were able to adjust for the clustering that results from patients admitted to the same hospital being more similar to each other than to those admitted to other hospitals (17). The model also incorporated a broad range of patient and hospital characteristics that included insurance type (Medicare/Medicaid, self/none, or health maintenance organization/private), age, female gender, body mass index, white race, family history of coronary artery disease, hypertension, diabetes, current/recent smoker, hyperlipidemia, prior myocardial infarction, prior percutaneous coronary intervention, prior coronary artery bypass grafting surgery, prior CHF, prior stroke, renal insufficiency, ST-segment depression, transient ST-segment elevation, signs of CHF at presentation, heart rate, systolic blood pressure, total number of hospital beds, teaching versus academic institution, and cardiologist care. From the multivariable analyses, the effect of age was then determined after adjustment for confounding factors between comparison groups.

Finally, we explored in-hospital mortality for older and younger patients after adjusting for baseline characteristics and the number of recommended ACS treatments they received in which we modeled the number of recommended treatments as an ordinal variable. Five treatments were considered: 1) early aspirin, 2) early beta-blockers, 3) early heparin (any), 4) early glycoprotein IIb/IIIa inhibition and catheterization within 48 h, and 5) catheterization within 48 h. All analyses were performed with SAS software version 8.2 (SAS institute Inc., Cary, North Carolina).


    Results
 Top
 Abstract
 Methods
 Results
 Discussion
 Conclusions
 References
 
Demographics and clinical characteristics of the 56,963 NSTE ACS patients are shown by four age groups (Table 1). The majority of our population was age 65 years or older (58%), with 11.2% being ≥85 years old, and the oldest patient being 103 years old. The vast majority of patients had positive cardiac markers (>85%), and many had ST-segment depression at presentation as well (~40%). Elderly patients were more likely to have positive markers and CHF at presentation than younger patients (91.6% positive markers and 41.4% CHF in the ≥85 age group). With advancing age, elderly patients had a declining prevalence of cardiac risk factors (diabetes, hyperlipidemia, smoking), but an increasing history of known cardiac disease (prior CHF, myocardial infarction, or coronary artery bypass grafting). In addition, elderly patients had more comorbidity (renal insufficiency, stroke, and hypertension). Thus, among an already high-risk population, older age predicted a greater burden of comorbidity and disease severity at presentation. In addition, older patients were more likely to be treated at smaller, non-academic hospitals, and less likely to be treated by specialists.


View this table:
[in this window]
[in a new window]
 
Table 1. Baseline Demographics and Clinical Characteristics*
 
With advancing age, medication contraindications were reported more often for early and discharge therapies. Among medications, contraindication rates varied from 2.6% for contraindications to lipid-lowering agents to 13.4% for glycoprotein IIb/IIIa inhibitors. Reported contraindication rates tended to increase with advancing patient age (Fig. 1).



View larger version (20K):
[in this window]
[in a new window]
 
Figure 1 Contraindications to short-term therapies by age and drug type. Includes contraindications defined by clinical criteria or provider discretion that use of the agent was contraindicated in specific patients. Open bars = <65 years old; grey bars = 65 to 74 years old; ruled bars = 75 to 84 years old; black bars = ≥85 years old. GP = glycoprotein.

 
The percentages and adjusted odds ratios for use among eligible patients of early in-hospital medications by age group are shown in Table 2 and Figure 2A. In-hospital use of aspirin and beta-blockers had small but statistically significant reductions in use past 65 years of age, and heparin had a small but significant reduction in use past 85 years of age. Age had its most notable impact on use of acute clopidogrel and platelet glycoprotein IIb/IIIa inhibitors. Despite 92% of patients age >85 years having positive cardiac markers, only 30% received clopidogrel, whereas 12.8% received platelet glycoprotein IIb/IIIa inhibitors.


View this table:
[in this window]
[in a new window]
 
Table 2. Early (≤24 h of Admission) Medications and Early Procedural Care (≤48 h of Admission) by Age Group*
 


View larger version (21K):
[in this window]
[in a new window]
 
Figure 2 (A) Short-term use of medications within the first 24 h of admission by age (among those with no contraindications). (B) Use of in-hospital diagnostic and invasive procedures by age. (C) In-hospital mortality by age. (D) Discharge use of medications by age (among those with no contraindications). ACE = angiotensin-converting enzyme; CABG = coronary artery bypass grafting; Cath = catheterization; GP = glycoprotein; PCI = percutaneous coronary intervention.

 
During their hospitalization, elderly patients were less likely to undergo early invasive care or revascularization procedures (Fig. 2B, Table 2). The use of an early invasive strategy, defined as diagnostic coronary angiography within 48 h of admission, tapered with age starting around the age of 70 years (Fig. 2B). Past the age of 75 years, only 40% underwent early invasive care, and past age 85 that number was <20%. We also examined therapies used among invasively managed patients. As seen in Table 3, use of clopidogrel and glycoprotein IIb/IIIa inhibitors was significantly lower among invasively managed elderly patients compared with similarly managed younger patients.


View this table:
[in this window]
[in a new window]
 
Table 3. Early Clopidogrel and Glycoprotein IIb/IIIa Inhibitor Use in Patients Managed With Early Invasive Strategy (Cath ≤48 h From Admission) Versus Conservative Care (Cath >48 h After Admission or No Cath)*
 
The risk of in-hospital death increased continuously with patient age from 1.9% for age <65 to 11.5% for age ≥85 years (Fig. 2C). After adjustment for patient and hospital factors, the odds ratio of in-hospital death for older age groups compared with age <65 was 1.88 for patients age 65 to 74 years, 2.46 for those ages 75 to 84 years, and 3.00 for those age ≥85 years. (Table 4) Other adverse in-hospital events also increased steadily with age, and included recurrent myocardial infarction, CHF, stroke, and transfusion. Most notable among these was CHF, which increased three-fold between age 65 and 85 years (unadjusted rates: age <65 years, 5.1%, vs. age ≥85 years, 16.7%).


View this table:
[in this window]
[in a new window]
 
Table 4. In-Hospital Outcomes After Acute Coronary Syndrome by Age*
 
The use of five guidelines-recommended therapies (aspirin, heparin, ß-blockers, glycoprotein IIb/IIIa inhibition, and catheterization) was also associated with a lower likelihood of in-hospital mortality (Fig. 3). After adjusting for other factors, in-hospital death was lowered by an increasing use of recommended therapies for both patients age ≥75 years and patients age <75 years alike (odds ratio, 0.79; 95% confidence interval, 0.75 to 0.83; and odds ratio, 0.71; 95% confidence interval, 0.67 to 0.75, respectively). A formal test for interaction between treatment and age was significant because of the larger difference in mortality between younger and older patients given fewer therapies compared with those given all five therapies. This indicates a similar or greater impact of treatment on outcomes in elderly patients.



View larger version (18K):
[in this window]
[in a new window]
 
Figure 3 Adjusted in-hospital mortality among older and younger patients undergoing an early invasive strategy by the number of guideline recommendations applied (cardiac catheterization, short-term aspirin, short-term beta-blocker, short-term heparin, and short-term glycoprotein IIb/IIIa inhibitors). Dashed line = ≥75 years old; solid line = <75 years old.

 
For those who survived to hospital discharge, percentages and adjusted odds ratios for use of discharge medications by age group are shown only among those with no reported contraindications and with specific indications (Table 5 and Fig. 2D). After adjustment, discharge use of aspirin, beta-blockers, and angiotensin-converting enzyme inhibitors was not influenced by patient age. However, lipid-lowering agents and clopidogrel use were significantly lower in elderly patients than in younger patients.


View this table:
[in this window]
[in a new window]
 
Table 5. Discharge Medications by Age Group*
 

    Discussion
 Top
 Abstract
 Methods
 Results
 Discussion
 Conclusions
 References
 
The ACC/AHA guidelines for the treatment of NSTE ACS do not alter therapeutic recommendations based on age, apart from encouraging attention to comorbidities, preferences, and appropriate dosing of medications in elderly patients (1,2). In contrast to these guidelines, however, we found that use of many recommended therapies was lower among elderly patients even after controlling for contraindications and comorbidities. Remaining age gaps were particularly notable in three areas: 1) early use of intravenous medications, 2) use of invasive care, and 3) use of lipid-lowering agents and clopidogrel at discharge. We consider reasons and implications for remaining age gaps in guidelines-recommended care.

Early use of medications.   Age had a relatively modest impact on the early use of aspirin and beta-blockers. However, the early use of heparin, platelet glycoprotein IIb/IIIa inhibitors, and clopidogrel decreased significantly among those age ≥75 years. The remaining gaps in recommended care may originate from uncertainty regarding the impact of age on expected treatment effects (18,19). However, randomized clinical trials have found that unfractionated heparin and low-molecular-weight heparin are effective in both young and old patients (20–22). Similarly, evidence also shows a benefit of platelet glycoprotein IIb/IIIa inhibitors in young and elderly patients with electrocardiograph changes or positive enzymes regardless of age, particularly if undergoing invasive management (23,24).

Delayed identification of ACS in elderly patients may further explain lower use of early therapies. Elderly patients are much less likely to present with classic chest pain, so diagnosis may wait until cardiac markers are elevated (25). In addition, elderly patients often have ACS coexisting with other acute illnesses, such as CHF or pneumonia, which may be the focus of initial care. However, because recurrent events are most likely to occur early in the hospitalization, this gap in early use of therapies contributes to adverse short-term outcomes such as reinfarction, CHF, and death.

Physicians may also withhold therapy in elderly patients because of safety concerns arising from comorbidity and potential drug contraindications with age (Fig. 1). Age-related alterations in drug clearance increase bleeding risks (26). However, we found that use was still lower in elderly patients after excluding those with investigator-documented non-eligibility. Safety concerns should be considered in light of the potential harm caused by withholding effective therapies in high-risk elderly patients.

Less invasive care.   The use of an invasive management strategy declines most precipitously with age. In the CRUSADE initiative, <50% of patients over the age of 65 years and only 11.2% of patients over the age of 85 years received early invasive care, despite 90% having positive cardiac markers. This conservative management of elderly ACS patients is similar to that found in prior studies (27). Although the debate about the ideal management for ACS continues, evidence from recent studies confirms a benefit of an early invasive approach in both young and old patients (28–31). The Treat Angina with Aggrastat and Determine Cost of Therapy with an Invasive or Conservative Strategy (TACTICS) Thrombolysis In Myocardial Infarction (TIMI)-18 trial found an early invasive strategy conferred a 56% relative reduction in death or myocardial infarction at six months in patients with NSTE ACS older than 75 years of age who received early invasive management compared with those treated with a conservative management strategy (32). Similarly, the Trial of Invasive versus Medical therapy in Elderly patients (TIME) study (33,34) and the Alberta Provincial Project for Outcomes Assessment in Coronary Heart Disease (APPROACH) study emphasized that older patients who underwent aggressive revascularization therapies had greater absolute risk reductions than younger patients (35).

Although patient preferences may also play a role in the conservative care of elderly patients, most elderly patients are willing to consider revascularization if recommended by their physicians (36). Thus, increasing the use of early invasive care and revascularization may be another opportunity for improving outcomes for elderly patients with NSTE ACS.

Discharge medications.   The discharge use of aspirin, beta-blockers, and angiotensin-converting enzyme inhibitors did not decline with advancing age, suggesting that age gaps have narrowed over time in the use of these discharge medications (7,11–13). The limited use of lipid-lowering agents in elderly patients was the most notable finding among discharge medications. Although debate continues regarding the benefit of lipid-lowering drugs in the >85 years age group, their benefits in patients of all ages have been confirmed in two large recent studies (37,38). Mounting evidence confirms benefit from lipid-lowering therapy in the short term after ACS, such that even those with limited life expectancy will benefit (39).

The use of clopidogrel at discharge largely parallels the use of an invasive strategy during hospitalization in elderly patients. Most notably, the CURE study found that use of clopidogrel after ACS without invasive procedures was effective in reducing death, myocardial infarction, and stroke in both young and older patients (40–42).

Study limitations.   The CRUSADE initiative is an observational study, thus unmeasured biases that influence the use of therapies may not have been captured. Specifically, contraindications were obtained during chart abstraction, not directly from the care team. However, this limitation should apply equally to patients of all ages, thereby minimally affecting observations across age groups. The CRUSADE initiative reports in-hospital outcomes, so conclusions about long-term mortality and quality of life implications for adherence to guidelines recommendations cannot be made from these data.


    Conclusions
 Top
 Abstract
 Methods
 Results
 Discussion
 Conclusions
 References
 
Optimizing the care of elderly patients with NSTE ACS is a timely imperative given the aging of the population. Applying evidence to the treatment of elderly patients falls short of recommendations in several areas. Physicians are understandably cautious regarding the application of newer therapies and early invasive care to high-risk elderly patients, and concerns over risks and side effects influence practice (43). Thus, future work on early recognition of ACS, safe application of acute treatments, and the use of secondary preventions in elderly patients should enable providers to further improve their outcomes after NSTE ACS.


    Acknowledgments
 
We acknowledge the effort and commitment of the site coordinators in the CRUSADE database for obtaining quality data, and David Bynum for excellent editorial assistance.


    Footnotes
 
The CRUSADE National Quality Improvement Initiative is funded by Millennium Pharmaceuticals, Inc, and Schering Corporation. Bristol-Myers Squibb/Sanofi Pharmaceuticals Partnership provides additional funding support. Drs. Roe, Pollack, Boden, Smith, Gibler, Ohman, and Peterson have served either on speakers' bureaus and/or have received research grants from the sponsors of the CRUSADE National Quality Improvement Initiative.


    References
 Top
 Abstract
 Methods
 Results
 Discussion
 Conclusions
 References
 
1. Braunwald E, Antman EM, Beasley JW, et al. ACC/AHA guidelines for management of patients with unstable angina and non–ST-elevation myocardial infarction: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on the Management of Patients with Unstable Angina) Circulation 2002;106:1893-1900.[Free Full Text]

2. Braunwald E, Antman EM, Beasley JW, et al. ACC/AHA guidelines for the management of patients with unstable angina and non–ST-segment elevation myocardial infarction: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on the Management of Patients with Unstable Angina) J Am Coll Cardiol 2000;36:970-1062.[Free Full Text]

3. Cannon CP, Turpie AG. Unstable angina and non–ST-elevation myocardial infarction: initial antithrombotic therapy and early invasive strategy Circulation 2003;107:2640-2645.[Free Full Text]

4. Giugliano RP, Camargo CA, Lloyd-Jones DM, et al. Elderly patients receive less aggressive medical and invasive management of unstable angina: potential impact of practice guidelines Arch Intern Med 1998;158:1113-1120.[Abstract/Free Full Text]

5. Giugliano RP, Lloyd-Jones DM, Camargo Jr. CA, Makary MA, O'Donnell CJ. Association of unstable angina guideline care with improved survival Arch Intern Med 2000;160:1775-1780.[Abstract/Free Full Text]

6. McLaughlin TJ, Soumerai SB, Willison DJ, et al. Adherence to national guidelines for drug treatment of suspected acute myocardial infarction: evidence for undertreatment in women and elderly patients Arch Intern Med 1996;156:799-805.[Abstract/Free Full Text]

7. Jencks SF, Huff ED, Cuerdon T. Change in the quality of care delivered to Medicare beneficiaries, 1998-1999 to 2000-2001 JAMA 2003;289:305-312.[Abstract/Free Full Text]

8. Gurwitz JH, Goldberg RJ, Chen Z, Gore JM. Beta-blocker therapy in acute myocardial infarction: evidence for underutilization in elderly patients Am J Med 1992;93:605-610.[CrossRef][Web of Science][Medline]

9. Alexander KP, Peterson ED, Mahaffey KW, et al. Potential impact of evidence-based medicine in acute coronary syndromes: insights from GUSTO IIbGlobal Use of Strategies to Open Occluded Arteries in Acute Coronary Syndromes trial. J Am Coll Cardiol 1998;32:2023-2030.[Abstract/Free Full Text]

10. Soumerai SB, McLaughlin TJ, Spiegelman D, Hertzmark E, Thibault G, Goldman L. Adverse outcomes of underuse of beta-blockers in elderly survivors of acute myocardial infarction JAMA 1997;277:115-121.[Abstract/Free Full Text]

11. Rathore SS, Mehta RH, Wang Y, Radford MJ, Krumholz HM. Effects of age on the quality of care provided to older patients with acute myocardial infarction Am J Med 2003;114:307-315.[CrossRef][Web of Science][Medline]

12. 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.[Abstract/Free Full Text]

13. Krumholz HM, Radford MJ, Ellerbeck EF, et al. Aspirin in the treatment of acute myocardial infarction in elderly Medicare beneficiariesPatterns of use and outcomes. Circulation 1995;92:2841-2847.[Abstract/Free Full Text]

14. Krumholz HM, Philbin DM, Wang Y, et al. Trends in the quality of care for Medicare beneficiaries admitted to the hospital with unstable angina J Am Coll Cardiol 1998;31:957-963.[Abstract/Free Full Text]

15. Shahi CN, Rathore SS, Wang Y, et al. Quality of care among elderly patients hospitalized with unstable angina Am Heart J 2001;142:263-270.[CrossRef][Web of Science][Medline]

16. Hoekstra JW, Pollack Jr. CV, Roe MT, et al. Improving the care of patients with non–ST-elevation acute coronary syndromes in the emergency department: the CRUSADE initiative Acad Emerg Med 2002;9:1146-1155.[CrossRef][Web of Science][Medline]

17. Liang KY, Zeger SL. Longitudinal data analysis using generalized linear models Biometrika 1986;73:13-22.[Abstract/Free Full Text]

18. Lee PY, Alexander KP, Hammill BG, Pasquali SK, Peterson ED. Representation of elderly persons and women in published randomized trials of acute coronary syndromes JAMA 2001;286:708-713.[Abstract/Free Full Text]

19. Peterson ED, Lytle BL, Biswas MS, Coombs L. Willingness to participate in cardiac trials Am J Geriatr Cardiol 2004;13:11-15.[Medline]

20. Oler A, Whooley MA, Oler J, Grady D. Adding heparin to aspirin reduces the incidence of myocardial infarction and death in patients with unstable anginaA meta-analysis. JAMA 1996;276:811-815.[Abstract/Free Full Text]

21. Krumholz HM, Hennen J, Ridker PM, et al. Use and effectiveness of intravenous heparin therapy for treatment of acute myocardial infarction in elderly patients J Am Coll Cardiol 1998;31:973-979.[Abstract/Free Full Text]

22. Eikelboom JW, Anand SS, Malmberg K, Weitz JI, Ginsberg JS, Yusef S. Unfractionated heparin and low-molecular-weight heparin in acute coronary syndrome without ST-elevation: a meta-analysis Lancet 2000;355:1936-1942.[CrossRef][Web of Science][Medline]

23. The PURSUIT Study Investigators Inhibition of platelet glycoprotein IIb/IIIa with eptifibatide in patients with acute coronary syndromes N Engl J Med 1998;339:436-443.[Abstract/Free Full Text]

24. Boersma E, Harrington RA, Moliterno DJ, et al. Platelet glycoprotein IIb/IIIa inhibitors in acute coronary syndromes: a meta-analysis of all major randomized clinical trials Lancet 2002;359:189-198.[CrossRef][Web of Science][Medline]

25. Milner KA, Vaccarino V, Arnold AL, Funk M, Goldberg RJ. Gender and age differences in chief complaints of acute myocardial infarction (Worcester Heart Attack Study) Am J Cardiol 2004;93:606-608.[CrossRef][Web of Science][Medline]

26. Moscucci M, Fox KA, Cannon CP, et al. Predictors of major bleeding in acute coronary syndromes: the Global Registry of Acute Coronary Events (GRACE) Eur Heart J 2003;24:1815-1823.[Abstract/Free Full Text]

27. Alexander KP, Galanos AN, Jollis J, Stafford J, Peterson ED. Post-myocardial infarction risk stratification in elderly patients Am Heart J 2001;142:37-42.[CrossRef][Web of Science][Medline]

28. Cannon CP, Weintraub WS, Demopoulos LA, et al. for the TACTICS-Thrombolysis In Myocardial Infarction-18 investigatorsComparison of early invasive and conservative strategies in patients with unstable coronary syndromes treated with the glycoprotein IIb/IIIa inhibitor tirofiban. N Engl J Med 2001;344:1879-1887.[Abstract/Free Full Text]

29. Wallentin L, Lagerqvist B, Husted S, Kontny F, Stahle E, Swahn E. Outcome at 1 year after an invasive compared with a non-invasive strategy in unstable coronary-artery disease: the FRISC II invasive randomised trialFRISC II Investigators. Fast Revascularisation during Instability in Coronary artery disease. Lancet 2000;356:9-16.[CrossRef][Web of Science][Medline]

30. Fox KA, Poole-Wilson PA, Henderson RA, et al. Interventional versus conservative treatment for patients with unstable angina or non–ST-elevation myocardial infarction: the British Heart Foundation RITA 3 randomised trialRandomized Intervention Trial of unstable Angina. Lancet 2002;360:743-751.[CrossRef][Web of Science][Medline]

31. Morrow DA, Cannon CP, Rifai N, et al. Ability of minor elevations of troponin I and T to predict benefit from an early invasive strategy in patients with unstable angina and non–ST-elevation myocardial infarction: results from a randomized trial JAMA 2001;286:2405-2412.[Abstract/Free Full Text]

32. Bach RG, Cannon CP, Weintraub WS, et al. The effect of routine, early invasive management on outcome for elderly patients with non–ST-segment elevation acute coronary syndromes Ann Intern Med 2004;141:186-195.[Abstract/Free Full Text]

33. Pfisterer M, Buser P, Osswald S, et al. Outcome of elderly patients with chronic symptomatic coronary artery disease with an invasive vs optimized medical treatment strategy: one-year results of the randomized TIME trial JAMA 2003;289:1117-1123.[Abstract/Free Full Text]

34. TIME investigators Trial of invasive vs. medical therapy in elderly patients with chronic symptomatic CAD (TIME): a randomized trial Lancet 2001;358:951-957.[CrossRef][Web of Science][Medline]

35. Graham MM, Ghali WA, Farls PD, Galbraith PD, Norris CM, Knudtson ML, Alberta Provincial Project for Outcomes Assessment in Coronary Heart Disease (APPROACH) Investigators Survival after coronary revascularization in elderly patients Circulation 2002;205:2378-2384.

36. Alexander KP, Harding TM, Coombs LP, Taylor K, Peterson ED. Effect of age on goals from cardiac care Am J Geriatr Cardiol 2002;11:134A.

37. Heart Protection Study Collaborative Group MRC/BHF Heart Protection Study of cholesterol lowering with simvastatin in 20,536 high-risk individuals: a randomized placebo-controlled trial Lancet 2002;360:7-22.[CrossRef][Web of Science][Medline]

38. Shepherd J, Blauw GJ, Murphy MB, et al. , for the PROSPER study group. PROspective Study of Pravastatin in elderly patients at Risk Pravastatin in elderly individuals at risk of vascular disease a randomised controlled trialLancet 2002;360:1623-1630.

39. Cannon CP. PROVE–IT TIMI 22 Study: Potential Effects on Critical Pathways for Acute Coronary Syndrome Crit Pathways Cardiol 2003;2:188-196.[CrossRef]

40. The CURE Investigators Effects of clopidogrel in addition to aspirin in patients with acute coronary syndromes without ST-segment elevation N Engl J Med 2001;345:494-502.[Abstract/Free Full Text]

41. Budaj A, Yusuf S, Metha S, et al. Benefit of clopidogrel in patients with acute coronary syndromes without ST-segment elevation in various risk groups Circulation 2002;106:1622-1626.[Abstract/Free Full Text]

42. The CAPRIE Steering Committee A randomized, blinded, trial of clopidogrel versus aspirin in patient at risk of ischemic events Lancet 1996;348:1329-1339.[CrossRef][Web of Science][Medline]

43. Cabana MD, Rand CS, Powe NR, et al. Why don't physicians follow clinical practice guidelines? A framework for improvement JAMA 1999;282:1458-1465.[Abstract/Free Full Text]




This article has been cited by other articles:


Home page
HeartHome page
D P Chew, L T Huynh, D Liew, C Astley, A Soman, and D Brieger
Potential survival gains in the treatment of myocardial infarction
Heart, November 15, 2009; 95(22): 1844 - 1850.
[Abstract] [Full Text] [PDF]


Home page
Circ Cardiovasc Qual OutcomesHome page
W. R. Lewis, A. G. Ellrodt, E. Peterson, A. F. Hernandez, K. A. LaBresh, C. P. Cannon, W. Pan, and G. C. Fonarow
Trends in the Use of Evidence-Based Treatments for Coronary Artery Disease Among Women and the Elderly: Findings From the Get With the Guidelines Quality-Improvement Program
Circ Cardiovasc Qual Outcomes, November 1, 2009; 2(6): 633 - 641.
[Abstract] [Full Text] [PDF]


Home page
J Am Coll CardiolHome page
K. K. Teo, S. P. Sedlis, W. E. Boden, R. A. O'Rourke, D. J. Maron, P. M. Hartigan, M. Dada, V. Gupta, J. A. Spertus, W. J. Kostuk, et al.
Optimal medical therapy with or without percutaneous coronary intervention in older patients with stable coronary disease: a pre-specified subset analysis of the COURAGE (Clinical Outcomes Utilizing Revascularization and Aggressive druG Evaluation) trial.
J. Am. Coll. Cardiol., September 29, 2009; 54(14): 1303 - 1308.
[Abstract] [Full Text] [PDF]


Home page
Circ Cardiovasc Qual OutcomesHome page
E. D. Peterson, M. T. Roe, J. S. Rumsfeld, R. E. Shaw, R. G. Brindis, G. C. Fonarow, and C. P. Cannon
A Call to ACTION (Acute Coronary Treatment and Intervention Outcomes Network): A National Effort to Promote Timely Clinical Feedback and Support Continuous Quality Improvement for Acute Myocardial Infarction
Circ Cardiovasc Qual Outcomes, September 1, 2009; 2(5): 491 - 499.
[Abstract] [Full Text] [PDF]


Home page
HeartHome page
C. Melloni and L K. Newby
Risk factor management after acute coronary syndromes
Heart, September 1, 2009; 95(17): 1382 - 1384.
[Full Text] [PDF]


Home page
J Am Coll CardiolHome page
R. D. Lopes, K. P. Alexander, S. V. Manoukian, M. E. Bertrand, F. Feit, H. D. White, C. V. Pollack Jr, J. Hoekstra, B. J. Gersh, G. W. Stone, et al.
Advanced Age, Antithrombotic Strategy, and Bleeding in Non-ST-Segment Elevation Acute Coronary Syndromes: Results From the ACUITY (Acute Catheterization and Urgent Intervention Triage Strategy) Trial
J. Am. Coll. Cardiol., March 24, 2009; 53(12): 1021 - 1030.
[Abstract] [Full Text] [PDF]


Home page
J CARDIOVASC PHARMACOL THERHome page
K. P. Alexander, M. A. Blazing, R. S. Rosenson, E. Hazard, W. S. Aronow, S. C. Smith Jr, and E. M. Ohman
Management of Hyperlipidemia in Older Adults
Journal of Cardiovascular Pharmacology and Therapeutics, March 1, 2009; 14(1): 49 - 58.
[Abstract] [PDF]


Home page
J Am Coll Cardiol IntvHome page
J. S. Hochman and A. H. Skolnick
Contemporary Management of Cardiogenic Shock: Age Is Opportunity
J. Am. Coll. Cardiol. Intv., February 1, 2009; 2(2): 153 - 155.
[Full Text] [PDF]


Home page
Ann. Thorac. Surg.Home page
B. Zingone, G. Gatti, E. Rauber, P. Tiziani, L. Dreas, A. Pappalardo, B. Benussi, and A. Spina
Early and Late Outcomes of Cardiac Surgery in Octogenarians
Ann. Thorac. Surg., January 1, 2009; 87(1): 71 - 78.
[Abstract] [Full Text] [PDF]


Home page
J Am Coll Cardiol IntvHome page
A. M. From, C. S. Rihal, R. J. Lennon, D. R. Holmes Jr, and A. Prasad
Temporal Trends and Improved Outcomes of Percutaneous Coronary Revascularization in Nonagenarians
J. Am. Coll. Cardiol. Intv., December 1, 2008; 1(6): 692 - 698.
[Abstract] [Full Text] [PDF]


Home page
JAMAHome page
R. H. Mehta, L. Liang, A. M. Karve, A. F. Hernandez, J. S. Rumsfeld, G. C. Fonarow, and E. D. Peterson
Association of Patient Case-Mix Adjustment, Hospital Process Performance Rankings, and Eligibility for Financial Incentives
JAMA, October 22, 2008; 300(16): 1897 - 1903.
[Abstract] [Full Text] [PDF]


Home page
Eur Heart JHome page
R. D. Lopes, K. P. Alexander, G. Marcucci, H. D. White, S. Spinler, J. Col, P. E. Aylward, R. M. Califf, and K. W. Mahaffey
Outcomes in elderly patients with acute coronary syndromes randomized to enoxaparin vs. unfractionated heparin: results from the SYNERGY trial
Eur. Heart J., August 1, 2008; 29(15): 1827 - 1833.
[Abstract] [Full Text] [PDF]


Home page
J Am Coll CardiolHome page
H. V. Anderson
Drug-Eluting Stents: Life Insurance With a Better Death Benefit
J. Am. Coll. Cardiol., May 27, 2008; 51(21): 2025 - 2027.
[Full Text] [PDF]


Home page
J Am Coll CardiolHome page
W. E. Boden and D. J. Maron
Reducing Post-Myocardial Infarction Mortality in the Elderly: The Power and Promise of Secondary Prevention
J. Am. Coll. Cardiol., April 1, 2008; 51(13): 1255 - 1257.
[Full Text] [PDF]


Home page
Eur Heart JHome page
T. Bauer, O. Koeth, C. Junger, T. Heer, H. Wienbergen, A. Gitt, R. Zahn, J. Senges, U. Zeymer, and for the Acute Coronary Syndromes Registry (ACOS) I
Effect of an invasive strategy on in-hospital outcome in elderly patients with non-ST-elevation myocardial infarction
Eur. Heart J., December 1, 2007; 28(23): 2873 - 2878.
[Abstract] [Full Text] [PDF]


Home page
J Am Coll CardiolHome page
J. L. Anderson, C. D. Adams, E. M. Antman, C. R. Bridges, R. M. Califf, D. E. Casey Jr, W. E. Chavey II, F. M. Fesmire, J. S. Hochman, T. N. Levin, et al.
ACC/AHA 2007 Guidelines for the Management of Patients With Unstable Angina/Non-ST-Elevation Myocardial Infarction: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 2002 Guidelines for the Management of Patients With Unstable Angina/Non-ST-Elevation Myocardial Infarction) Developed in Collaboration with the American College of Emergency Physicians, the Society for Cardiovascular Angiography and Interventions, and the Society of Thoracic Surgeons Endorsed by the American Association of Cardiovascular and Pulmonary Rehabilitation and the Society for Academic Emergency Medicine
J. Am. Coll. Cardiol., August 14, 2007; 50(7): e1 - e157.
[Full Text] [PDF]


Home page
J Am Coll CardiolHome page
J. L. Anderson, C. D. Adams, E. M. Antman, C. R. Bridges, R. M. Califf, D. E. Casey Jr, W. E. Chavey II, F. M. Fesmire, J. S. Hochman, T. N. Levin, et al.
ACC/AHA 2007 Guidelines for the Management of Patients With Unstable Angina/Non ST-Elevation Myocardial Infarction Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 2002 Guidelines for the Management of Patients With Unstable Angina/Non ST-Elevation Myocardial Infarction) Developed in Collaboration with the American College of Emergency Physicians, the Society for Cardiovascular Angiography and Interventions, and the Society of Thoracic Surgeons Endorsed by the American Association of Cardiovascular and Pulmonary Rehabilitation and the Society for Academic Emergency Medicine
J. Am. Coll. Cardiol., August 14, 2007; 50(7): 652 - 726.
[Full Text] [PDF]


Home page
HypertensionHome page
C. Rosendorff, H. R. Black, C. P. Cannon, B. J. Gersh, J. Gore, J. L. Izzo Jr, N. M. Kaplan, C. M. O'Connor, P. T. O'Gara, and S. Oparil
REPRINT Treatment of Hypertension in the Prevention and Management of Ischemic Heart Disease: A Scientific Statement From the American Heart Association Council for High Blood Pressure Research and the Councils on Clinical Cardiology and Epidemiology and Prevention
Hypertension, August 1, 2007; 50(2): e28 - e55.
[Full Text] [PDF]


Home page
Eur Heart JHome page
Authors/Task Force Members, J.-P. Bassand, C. W. Hamm, D. Ardissino, E. Boersma, A. Budaj, F. Fernandez-Aviles, K. A.A. Fox, D. Hasdai, E. M. Ohman, et al.
Guidelines for the diagnosis and treatment of non-ST-segment elevation acute coronary syndromes: The Task Force for the Diagnosis and Treatment of Non-ST-Segment Elevation Acute Coronary Syndromes of the European Society of Cardiology
Eur. Heart J., July 1, 2007; 28(13): 1598 - 1660.
[Full Text] [PDF]


Home page
CirculationHome page
C. Rosendorff, H. R. Black, C. P. Cannon, B. J. Gersh, J. Gore, J. L. Izzo Jr, N. M. Kaplan, C. M. O'Connor, P. T. O'Gara, and S. Oparil
Treatment of Hypertension in the Prevention and Management of Ischemic Heart Disease: A Scientific Statement From the American Heart Association Council for High Blood Pressure Research and the Councils on Clinical Cardiology and Epidemiology and Prevention
Circulation, May 29, 2007; 115(21): 2761 - 2788.
[Full Text] [PDF]


Home page
CirculationHome page
K. P. Alexander, L. K. Newby, C. P. Cannon, P. W. Armstrong, W. B. Gibler, M. W. Rich, F. Van de Werf, H. D. White, W. D. Weaver, M. D. Naylor, et al.
Acute Coronary Care in the Elderly, Part I: Non-ST-Segment-Elevation Acute Coronary Syndromes: A Scientific Statement for Healthcare Professionals From the American Heart Association Council on Clinical Cardiology: In Collaboration With the Society of Geriatric Cardiology
Circulation, May 15, 2007; 115(19): 2549 - 2569.
[Abstract] [Full Text] [PDF]


Home page
J Am Coll CardiolHome page
H. M. Krumholz and F. A. Masoudi
The Year in Epidemiology, Health Services Research, and Outcomes Research
J. Am. Coll. Cardiol., November 7, 2006; 48(9): 1886 - 1895.
[Full Text] [PDF]


Home page
J Am Coll CardiolHome page
R. P. Giugliano and E. Braunwald
The Year in Non-ST-Segment Elevation Acute Coronary Syndromes
J. Am. Coll. Cardiol., July 18, 2006; 48(2): 386 - 395.
[Full Text] [PDF]


Home page
JAMAHome page
E. D. Peterson, M. T. Roe, J. Mulgund, E. R. DeLong, B. L. Lytle, R. G. Brindis, S. C. Smith Jr, C. V. Pollack Jr, L. K. Newby, R. A. Harrington, et al.
Association Between Hospital Process Performance and Outcomes Among Patients With Acute Coronary Syndromes
JAMA, April 26, 2006; 295(16): 1912 - 1920.
[Abstract] [Full Text] [PDF]


Home page
J Am Coll CardiolHome page
O. Ben-Yehuda
Upstream/Downstream: Glycoprotein IIb/IIIa in Non-ST-Segment Elevation Myocardial Infarction
J. Am. Coll. Cardiol., February 7, 2006; 47(3): 538 - 540.
[Full Text] [PDF]


Home page
J Am Coll CardiolHome page
H. V. Anderson and R. G. Bach
The Elderly Are Not So Old Anymore
J. Am. Coll. Cardiol., October 18, 2005; 46(8): 1488 - 1489.
[Full Text] [PDF]


This Article
Right arrow Abstract Freely available
Right arrow Figures Only
Right arrow Full Text (PDF)
Right arrow View Online Appendix
Right arrow All Versions of this Article:
j.jacc.2005.05.084v1
46/8/1479    most recent
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Alexander, K. P.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Alexander, K. P.

 
  CME Topic Collections Past Issues Search Current Issue Home

Advertisement