Download Influence of Inpatient Service Specialty on Care Processes and

Influence of Inpatient Service Specialty on Care Processes
and Outcomes for Patients With Non–ST-Segment Elevation
Acute Coronary Syndromes
Matthew T. Roe, MD, MHS; Anita Y. Chen, MS; Rajendra H. Mehta, MD; Yun Li, MS;
Ralph G. Brindis, MD, MPH; Sidney C. Smith, Jr, MD; John S. Rumsfeld, MD, PhD;
W. Brian Gibler, MD; E. Magnus Ohman, MD; Eric D. Peterson, MD, MPH
Downloaded from http://circ.ahajournals.org/ by guest on August 10, 2017
Background—Since the broad dissemination of practice guidelines, the association of specialty care with the treatment of
patients with acute coronary syndromes has not been studied.
Methods and Results—We evaluated 55 994 patients with non–ST-segment elevation acute coronary syndromes (ischemic
ST-segment changes and/or positive cardiac markers) included in the CRUSADE (Can Rapid Risk Stratification of
Unstable Angina Patients Suppress Adverse Outcomes With Early Implementation of the ACC/AHA Guidelines)
Quality Improvement Initiative from January 2001 through September 2003 at 301 tertiary US hospitals with full
revascularization capabilities. We compared baseline characteristics, the use of American College of Cardiology/
American Heart Association guidelines class I recommendations, and in-hospital outcomes by the specialty of the
primary in-patient service (cardiology versus noncardiology). A total of 35 374 patients (63.2%) were primarily cared
for by a cardiology service, and these patients had lower-risk clinical characteristics, but they more commonly received
acute (ⱕ24 hours) medications, invasive cardiac procedures, and discharge medications and lifestyle interventions.
Acute care processes were improved when care was provided by a cardiology service regardless of the propensity to
receive cardiology care. The adjusted risk of in-hospital mortality was lower with care provided by a cardiology service
(adjusted odds ratio 0.80, 95% confidence interval 0.73 to 0.88), and adjustment for differences in the use of acute
medications and invasive procedures partially attenuated this mortality difference (adjusted odds ratio 0.92, 95%
confidence interval 0.83 to 1.02).
Conclusions—Non–ST-segment elevation acute coronary syndrome patients primarily cared for by a cardiology inpatient
service more commonly received evidence-based treatments and had a lower risk of mortality, but these patients had
lower-risk clinical characteristics. Results from the present analysis highlight the difficulties with accurately determining
how specialty care is associated with treatment patterns and clinical outcomes for patients with acute coronary
syndromes. Novel methodologies for evaluating the influence of specialty care for these patients need to be developed
and applied to future studies. (Circulation. 2007;116:1153-1161.)
Key Words: coronary disease 䡲 patients 䡲 patient care 䡲 medical specialties 䡲 guidelines
R
andomized clinical trials have produced valuable
insights into the treatment of patients with non–STsegment elevation (NSTE) acute coronary syndromes
(ACS), insights that have been summarized into practice
guidelines by the American College of Cardiology (ACC)
and American Heart Association (AHA).1,2 Studies from
the last decade demonstrated that patients with acute
myocardial infarction (MI) cared for by a cardiology
inpatient service were more likely to receive guidelines-
Clinical Perspective p 1161
based treatment.3,4 Since these studies were performed,
however, multiple parties, including the government, insurance companies, managed care organizations, academic organizations, and professional societies, have contributed to
regional and national quality improvement programs designed to promote guidelines-based care for patients with
ACS.5– 8 Whether these efforts have reduced or eliminated
Received February 15, 2007; accepted June 15, 2007.
From Duke University Medical Center and Duke Clinical Research Institute (M.T.R., A.Y.C., R.H.M., E.M.O., E.D.P.), Durham, NC; Department of
Biostatistics, University of Michigan (Y.L.), Ann Arbor; Kaiser-Permanente Health System (R.G.B.), San Francisco Medical Center, San Francisco, Calif;
University of North Carolina School of Medicine (S.C.S.), Chapel Hill, NC; Section of Cardiology (J.S.R.), Denver Veterans Affairs Medical
Center/Division of Cardiology, University of Colorado Health Sciences Center, Denver, Colo; and the University of Cincinnati College of Medicine
(W.B.G.), Cincinnati, Ohio.
The online-only Data Supplement, consisting of 2 appendices, is available with this article at http://circ.ahajournals.org/cgi/content/full/
CIRCULATIONAHA.107.697003/DC1.
Correspondence to Matthew T. Roe, MD, MHS, Duke Clinical Research Institute, 2400 Pratt St, Durham, NC 27705. E-mail [email protected].
© 2007 American Heart Association, Inc.
Circulation is available at http://circ.ahajournals.org
DOI: 10.1161/CIRCULATIONAHA.107.697003
1153
1154
Circulation
September 4, 2007
differences in treatment patterns for ACS by physician
specialty remains unknown.
We sought to determine the contemporary relationship
between the specialty of the inpatient service and processes of
care and outcomes in patients with NSTE ACS included in
the CRUSADE (Can Rapid risk stratification of Unstable
angina patients Suppress ADverse outcomes with Early
implementation of the ACC/AHA guidelines) Quality Improvement Initiative. Our specific goals were to (1) describe
differences in patient characteristics according to whether
care was provided by a cardiology or a noncardiology service,
(2) evaluate differences in guidelines-recommended treatments and clinical outcomes among patients cared for by a
cardiology service versus those cared for by a noncardiology
service, and (3) delineate how differences in processes of care
by the specialty of the inpatient service are associated with
clinical outcomes.
Downloaded from http://circ.ahajournals.org/ by guest on August 10, 2017
Methods
Patient Inclusion Criteria
Patients included in the CRUSADE initiative presented with ischemic symptoms (ⱖ10 minutes) at rest within 24 hours of hospital
presentation and had at least 1 of the following diagnostic features
recommended by the ACC/AHA guidelines to distinguish patients
with an increased risk of adverse outcomes: ST-segment depression
ⱖ0.5 mm, transient ST-segment elevation 0.5 to 1.0 mm (which
lasted for ⬍10 minutes), and/or positive cardiac markers (elevated
troponin I or T and/or creatine kinase [CK]-MB greater than the
upper limit of normal for the local laboratory assay used at each
institution).1 Transfer-in patients were included if they were transferred in within 24 hours of the time of presentation to the outside
hospital.
Data Collection and Quality
Hospitals participating in CRUSADE collect detailed process-ofcare and in-hospital outcomes data through retrospective chart
review. Data are collected anonymously during the initial hospitalization, and because no patient identifiers are collected, patient
informed consent is not required. The institutional review board of
each institution approves participation in CRUSADE.
Participating institutions are instructed to submit consecutive
eligible patients to the CRUSADE database. Data are abstracted by
a trained data collector using standardized definitions. Data collected
include patient characteristics, the use of acute medications (within
24 hours of presentation), use and timing of invasive cardiac
procedures, laboratory results, physician and hospital characteristics,
and discharge therapies and interventions. Data collectors at participating sites were trained before commencing participation in CRUSADE with regard to the definitions of all variables and medication
contraindications listed on the data collection form (see Appendices
I and II in the online Data Supplement). For patients who were
transferred into a CRUSADE hospital and who met the inclusion
criteria, data collectors were instructed to utilize medical records
from the outside hospital to account for data relating to the initial
hospital presentation and for data concerning the administration of
acute (ⱕ24 hours) medications before transfer in.
The specialty of the primary inpatient service was defined by the
sites on the basis of the admitting service and the specialty of the
physician who had the most frequent and consistent notations in the
medical record. Data collectors were instructed to choose 1 of the
following 2 options for the specialty of the primary inpatient service:
cardiology or the composite of family practice/internal medicine/
other. Data collectors were also instructed to record whether a formal
cardiology consultation was performed (beyond the mere performance of a cardiac procedure) for patients primarily cared for by a
noncardiology service.
Various procedures have been established to maintain and monitor
the quality of data submitted to the CRUSADE database. At data
entry and during quarterly quality control analyses, values that
exceed expected ranges are flagged and excluded from analyses.
Additionally, sites receive a quarterly report summarizing data
quality problems.
Data quality was also verified with a random sampling of 5% of
the patients included in CRUSADE (n⫽220) within the first 6
months of data collection. The overall accuracy of audited records
was 94.8%. The overall degree of missing data averaged ⬇5% across
all collected data elements, but variables such as age and gender
were missing in ⬍0.5% of all audited cases.
Chart Abstraction
We performed a detailed abstraction of 85 patient charts that were
randomly selected from a larger group of charts that were collected
from sites participating in CRUSADE for an ongoing chart abstraction project. A single reviewer (MTR) independently reviewed each
chart and confirmed that the specialty of the inpatient service
denoted on the data collection form was accurate in all cases (100%).
Data on the characteristics of the presenting symptoms, comorbidities, timing of the first documentation of a positive cardiac marker,
and the primary clinical condition on presentation that were not
collected on the data collection form were abstracted to provide a
more in-depth characterization of patients primarily cared for by a
cardiology versus a noncardiology service.
Processes of Care
We examined guidelines recommendations for acute care (ⱕ24
hours from admission) designated as class IA or class IB by the
ACC/AHA guidelines, including the administration of aspirin or
clopidogrel (if aspirin was contraindicated), ␤-blockers, lowmolecular-weight or unfractionated heparin, and platelet glycoprotein IIb/IIIa inhibitors.1,2 We also evaluated the use and timing of
cardiac catheterization and revascularization procedures given the
class IA designation for early invasive management in the most
recent version of the ACC/AHA guidelines.2 Class IA or IB
recommendations for discharge care included aspirin; clopidogrel;
␤-blockers; ACE inhibitors for patients with heart failure (ejection
fraction ⬍40%), diabetes mellitus, or hypertension; and lipidlowering agents (for patients with hyperlipidemia or low-density
lipoprotein cholesterol ⬎100 mg/dL).1 Contraindications were collected for each medication class and are listed in Appendix II.
Analysis Cohort
We chose to evaluate only those patients admitted to tertiary
hospitals with full revascularization capabilities (percutaneous coronary intervention and coronary artery bypass grafting) because we
could not collect patient information after interhospital transfer and
to eliminate confounding related to the availability of invasive
cardiac procedures. From January 2001 (beginning of data collection
for CRUSADE) through September 2003, 57 800 NSTE ACS
patients were included in the CRUSADE database from 301 hospitals with full revascularization capabilities in 45 states across the
United States. We excluded 1334 patients (2.3%) who were transferred to other hospitals because complete in-hospital outcomes were
not available and 472 patients (⬍1%) with missing data on the
primary inpatient service, which left 55 994 patients in the final
analysis population. The transfer-out rates were 2.9% for patients
who received care from a noncardiology service and 2.0% for
patients who received care from a cardiology service.
Statistical Methods
Patient demographics, clinical characteristics, care patterns, and
in-hospital outcomes were compared among patients cared for by a
cardiology service versus those cared for by a noncardiology service
(internal medicine, family practice, or other). To test for independence of care by a cardiology service and patient characteristic, care
patterns, and outcomes, Mantel-Haenszel ␹2 test was used with
control for hospital site.
Roe et al
Downloaded from http://circ.ahajournals.org/ by guest on August 10, 2017
Because care provided by a cardiology service is not assigned
randomly in clinical practice, we used 2 separate statistical methods
to adjust for potential confounding in the treatment and outcome
comparisons in the present study. In our primary analyses, we used
a generalized estimating equation (GEE) method to adjust for patient
and hospital characteristics, including patient age, female sex, body
mass index, white race, insurance status, family history of premature
coronary artery disease, hypertension, diabetes mellitus, current/
recent smoker, hypercholesterolemia, prior MI, prior percutaneous
coronary intervention, prior coronary artery bypass grafting, prior
heart failure, prior stroke, renal insufficiency, ST-segment depression, transient ST-segment elevation, positive cardiac markers,
clinical signs of heart failure on presentation, presenting heart rate
and systolic blood pressure, academic/teaching institution, total
number of hospital beds, and geographic region within the United
States.9 The GEE method was used because patients admitted in the
same hospital tend to be more similar to each other than those in
different hospitals (ie, within-hospital clustering of responses). Odds
ratios and 95% confidence intervals were presented for care provided
by a cardiology service to examine the variation of the strength of its
influence on treatment patterns and clinical outcomes.
In addition, we reported the standardized mortality rates to
compare the absolute differences in mortality rates between patients
cared for by a cardiology service and those cared for by a noncardiology service. From the mortality model that adjusted for patient
and hospital characteristics, we obtained the probabilities of inhospital mortality. We then calculated a standardized mortality rate
by dividing the sum of observed mortality (observed) by the sum of
predicted probabilities of mortality (expected) among patients cared
for by a cardiology service and those cared for by a noncardiology
service and multiplied each observed-to-expected ratio by the mortality rate from the overall population.
Our secondary analyses used propensity methodology to compare
patient subgroups with similar likelihood for care by a cardiology
service.10 Specifically, a multivariable model was developed to
determine patient and hospital factors significantly associated with
care by a cardiology service. We categorized patients into 5 equal
groups that ranged from those with the lowest propensity for care by
a cardiology service (group 1) to those with the greatest propensity
for care by a cardiology service (group 5). We then explored acute
(ⱕ24 hours) treatment patterns and use of catheterization ⱕ48 hours
after presentation across the 5 propensity groups and displayed rates
of unadjusted in-hospital mortality according to care by a cardiology
service versus care by a noncardiology service within each of these
5 groups.
Finally, to examine whether treatment-related differences accounted for differences in mortality according to whether or not care
was provided by a cardiology service, we performed stepwise
adjustment modeling with the following covariates: (1) patient
characteristics, (2) patient and hospital characteristics, (3) patient and
hospital characteristics plus use of acute (ⱕ24 hours) medications
(aspirin, clopidogrel, ␤-blocker, unfractionated/low-molecularweight heparin, and glycoprotein IIb/IIIa inhibitors) and individual
contraindications for acute medications, and (4) patient and hospital
characteristics, acute medications, medication contraindications, and
catheterization ⱕ48 hours after presentation.
A probability value ⬍0.05 was considered significant for all tests.
All analyses were performed with SAS software (version 8.2, SAS
Institute, 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
Specialty of Inpatient Service
A total of 35 374 (63.1%) of 55 994 patients were primarily
cared for by a cardiology inpatient service. During the study
time period, the overall percentage of patients cared for by a
cardiology service did not vary significantly by quarter and
Physician Specialty and ACS Treatment
1155
Distribution of the percentage of patients primarily cared for by
a noncardiology service across the participating hospitals.
X-axis denotes the percentage of patients cared for by a noncardiology service in relation to the total number of patients
submitted from each hospital, and y-axis denotes the percentage of hospitals for each category on the x-axis.
was consistently between 61% and 65%. At the hospital level,
the percentage of patients primarily cared for by a noncardiology inpatient service varied widely (Figure 1). A total of
12 685 patients (22.7%) were transferred in from an outside
hospital.
Patient Features by Primary Inpatient Service
Patient and hospital characteristics according to the specialty
of the primary inpatient service in the overall sample of
55 994 patients are shown in Table 1. Data from the chart
abstraction project obtained from 85 patient charts demonstrate that the characteristics of the presenting symptoms and
the timing of documentation of the first positive cardiac
marker were similar regardless of the primary inpatient
service (Table 2). Patients primarily cared for by a noncardiology service were more likely to have a documented
“do-not-resuscitate” status. The primary clinical condition on
hospital presentation was not related to ACS in ⬇15% of the
patients regardless of the primary inpatient service. In the
multivariable model generated from the overall sample of
55 994 patients, factors most strongly associated with care by
a cardiology inpatient service included slower presenting
heart rate, younger age, male sex, prior revascularization
procedures, ischemic ST-segment changes, and lack of renal
insufficiency, prior heart failure, diabetes mellitus, or prior
stroke (Table 3).
Medication and Procedural Utilization
Patients cared for by a cardiology inpatient service were more
likely to receive short-term (ⱕ24 hours) and discharge
medications and to undergo invasive cardiac procedures
(Table 4). Similar findings were demonstrated when the
population was restricted to the 49 700 patients with NSTE
MI (positive cardiac markers).
Effect of Cardiology Consultation on
Care Processes
Among the 20 620 patients primarily cared for by a noncardiology service, 18 733 (90.9%) had a cardiology consulta-
1156
Circulation
TABLE 1.
September 4, 2007
Patient and Hospital Characteristics by Primary Inpatient Service
Variable
Overall
(n⫽55 994)
Cardiology
(n⫽35 374)
Noncardiology
(n⫽20 620)
71 (59, 80)
P
Demographics
Age, y*
⬍0.0001
67 (56, 78)
65 (55, 76)
Female sex
39.1
35.7
45.1
⬍0.0001
Black race
11.0
9.7
13.3
⬍0.0001
HMO/private
46.6
47.9
44.4
Medicare/Medicaid
45.7
43.4
49.7
6.7
7.8
4.9
Family history of CAD
37.0
39.6
32.6
⬍0.0001
Hypertension
68.9
67.2
72.0
⬍0.0001
Diabetes mellitus
32.2
29.9
36.0
⬍0.0001
Hyperlipidemia
48.5
50.7
44.7
⬍0.0001
Current/recent smoking
28.3
31.0
23.8
⬍0.0001
Renal insufficiency†
13.0
10.1
18.0
⬍0.0001
Prior MI
30.6
31.0
29.9
0.0126
Prior CHF
17.2
13.6
13.4
⬍0.0001
Prior PCI
22.7
25.3
18.2
⬍0.0001
Prior CABG
20.7
21.6
19.2
⬍0.0001
Prior stroke
10.3
8.5
13.4
⬍0.0001
⬍0.0001
Insurance status
Self/none
Medical history
Downloaded from http://circ.ahajournals.org/ by guest on August 10, 2017
Presenting features
Time from symptom onset to presentation, h*
2.8 (1.3, 7.2)
2.9 (1.3, 7.3)
2.8 (1.3, 7.0)
0.002
ST depression
39.8
40.8
38.1
⬍0.0001
Transient ST elevation
10.0
11.3
7.9
⬍0.0001
Positive cardiac markers
88.8
88.8
88.7
0.53
Signs of CHF
20.8
16.9
27.5
⬍0.0001
81 (69, 97)
79 (68, 93)
86 (72, 101)
⬍0.0001
144 (124, 165)
143 (124, 164)
146 (124, 167)
⬍0.0001
Total hospital beds*
419 (297, 549)
420 (297, 552)
410 (296, 532)
⬍0.0001
Teaching hospital‡
32.3
33.7
29.9
⬍0.0001
Length of stay, d*
4 (3, 7)
4 (2, 6)
5 (3, 8)
⬍0.0001
Heart rate, bpm*
Systolic BP, mm Hg*
Hospital features
Data are expressed as percentages except where indicated. HMO indicates health maintenance organization; CAD, coronary artery
disease; CHF, congestive heart failure; PCI, percutaneous coronary intervention; CABG, coronary artery bypass grafting; and BP, blood
pressure.
*Expressed as median (25th, 75th percentile).
†Creatinine ⬎2.0 mg/dL, calculated creatinine clearance ⬍30 mL/min, or need for chronic renal dialysis.
‡Member of the Council of Teaching Hospitals.
tion performed during the hospitalization, 1430 (6.9%) did
not have a consultation, and 457 (2.2%) had missing data on
cardiology consultation. The short-term use (ⱕ24 hours) of
aspirin (92.2% versus 82.4%), heparin (80.2% versus 52.7%),
glycoprotein IIb/IIIa inhibitors (25.5% versus 3.7%), clopidogrel (34.7% versus 15.0%), and early catheterization ⱕ48
hours after presentation (37.4% versus 4.1%) was higher
among those patients with than those without a consultation.
In-Hospital Outcomes
The frequency of adjusted in-hospital death, reinfarction, and
transfusion was lower in patients who received care from a
cardiology inpatient service (Table 5). Similar findings were
demonstrated when the population was restricted to the
49 700 patients with NSTE MI (positive cardiac markers).
The in-hospital mortality rate for the 472 patients who were
excluded due to missing data on the specialty of the primary
inpatient service was 8.7%.
Propensity Analysis and Care Processes
Among the 5 propensity groups, the average percentage of
patients cared for by a cardiology inpatient service ranged
from 47% in group 1% to 83% in group 5. Within each
propensity group, patients cared for by a cardiology inpatient
service were more likely to receive acute (ⱕ24 hours)
medications and cardiac catheterization within 48 hours, but
Roe et al
TABLE 2.
Physician Specialty and ACS Treatment
1157
Patient Characteristics From Chart Abstraction by Primary Inpatient Service
Overall
(n⫽85)
Cardiology
(n⫽46)
Ischemic symptoms documented on ED arrival
82.2
76.1
87.2
0.56
Typical chest pain
82.6
82.6
82.1
0.99
Variable
Noncardiology
(n⫽39)
P
Symptoms
Timing of first cardiac marker elevation
0.78
ⱕ12 h after arrival
87.1
89.1
84.6
䡠䡠䡠
⬎12 h after arrival
5.9
4.4
7.7
䡠䡠䡠
No positive markers
7.0
6.5
7.7
䡠䡠䡠
Comorbidities
Severe lung disease*
2.4
2.2
2.6
0.91
End-stage renal disease
3.5
2.2
5.1
0.46
Active malignancy
1.2
0
2.6
0.27
Severe cardiomyopathy†
2.4
4.4
0
0.19
Downloaded from http://circ.ahajournals.org/ by guest on August 10, 2017
Documented DNR status
4.7
0
10.3
0.03
ACS status: secondary ACS†
15.3
13.0
18.0
0.53
Data are expressed as percentages. ED indicates emergency department; DNR, do not resuscitate.
*Chronic obstructive pulmonary disease or pulmonary hypertension requiring home oxygen use.
†Dilated or ischemic cardiomyopathy (ejection fraction ⬍35%) with long-term treatment for heart failure.
‡Primary, presenting clinical condition not related to ACS. This includes patients who presented with an active
infection or sepsis, heart failure exacerbation, or an acute neurological event.
medication use decreased for both in-patient services as the
propensity to receive cardiology care decreased (Table 6).
Association of Care Processes With Mortality
After adjustment for patient and hospital characteristics in the
overall sample of 55 994 patients, the risk of mortality was
significantly lower among patients cared for by a cardiology
service (adjusted odds rato 0.80, 95% confidence interval
0.73 to 0.88; Table 4). After adjustment for differences in the
use of acute (ⱕ 24 hours) medications, individual patient
contraindications to acute medications, and the use of cardiac
catheterization within 48 hours, the mortality difference was
partially attenuated (adjusted odds ratio 0.92, 95% confidence
interval 0.83 to 1.02).
Discussion
We have demonstrated that in contemporary practice, nearly
40% of patients with NSTE ACS were primarily cared for by
a noncardiology service at tertiary hospitals with full revascularization capabilities. Patients cared for by a noncardiology service were older and had more comorbidities, were less
likely to receive guidelines-recommended medications and
invasive procedures, and had a higher risk of mortality.
Explanations for Treatment Differences
by Specialty
Differences in treatment patterns by specialty demonstrated
in the present analysis are likely related to multiple factors.
First, patients who received care from a noncardiology
service were older and had a greater burden of comorbid
medical conditions than patients cared for by a cardiology
service, so many of these patients may not have been ideal
candidates for guidelines-recommended treatments and may
have had undocumented medication contraindications that
were not accounted for in the present analyses. Second, we
demonstrated that the percentage of patients primarily cared
for by a noncardiology service varied significantly across the
participating hospitals, so hospitals likely did not have a
standard approach for determining which patients were admitted to a noncardiology service. There may thus have been
a selection bias for the disposition of “healthier” patients,
who would be expected to be better candidates for evidencebased therapies, for care by an inpatient cardiology service.
Finally, most (91%) of the patients in the present analysis
who were treated by a noncardiology service received a
cardiology consultation, but differences in treatment patterns
were still demonstrated by specialty, which indicates that
patient comorbidities and undocumented medication contraindications may have influenced treatment decisions to a
greater degree than input from cardiologists.11 Therefore,
evaluation of the association of specialty care with the
disposition and treatment of NSTE ACS patients is very
complicated.
Methodology for Examining the Effect of Specialty
Care on Outcomes
Studies that have examined the influence of specialty care on
the outcomes of patients with a variety of medical conditions
have yielded conflicting results, most likely due to methodological shortcomings. In a recent meta-analysis of 49 studies, those studies that favored specialist care over generalist
care frequently did not account for differences in case mix to
adjust for selection biases, did not adjust for the effects of
differences in practice environments, and did not consider
case volume or physician experience to quantify the expertise
of specialists.12 With regard to the influence of cardiology
care on patients with ACS and acute MI, prior studies have
shown that differences in case mix can bias treatment patterns
1158
Circulation
September 4, 2007
TABLE 3. Patient and Hospital Factors Significantly Associated With Care
Provided by a Cardiology Service
␹2
Adjusted OR
95% CI
P
Heart rate, per 10 bpm
191
0.93
0.92–0.94
⬍0.0001
Renal insufficiency*
107
0.71
0.66–0.76
⬍0.0001
Age, per 10 y
99
0.88
0.86–0.90
⬍0.0001
Prior PCI
82
1.32
1.24–1.40
⬍0.0001
⬍0.0001
Variable
Male sex
78
1.16
1.12–1.20
Signs of CHF
65
0.81
0.77–0.85
⬍0.0001
Diabetes mellitus
51
0.87
0.84–0.91
⬍0.0001
Prior stroke
49
0.80
0.75–0.85
⬍0.0001
Transient ST elevation†
47
1.41
1.26–1.57
⬍0.0001
ST depression†
1.16
1.10–1.22
Prior CABG
䡠䡠䡠
44
1.18
1.13–1.24
䡠䡠䡠
⬍0.0001
Prior CHF
38
0.85
0.81–0.89
⬍0.0001
Downloaded from http://circ.ahajournals.org/ by guest on August 10, 2017
Hyperlipidemia
36
1.14
1.09–1.19
⬍0.0001
White race
36
1.23
1.14–1.33
⬍0.0001
Positive cardiac
markers
22
1.21
1.12–1.31
⬍0.0001
Teaching hospital‡
18
2.36
1.58–3.54
⬍0.0001
Hypertension
9
0.95
0.91–0.98
0.003
Prior MI
7
1.06
1.02–1.10
0.008
Family history of CAD
5
1.05
1.01–1.10
0.02
Variables included in the model that were not significantly associated with cardiology care
(P⬎0.05) included region, insurance status, body mass index, current/recent smoker, total number
of hospital beds, and systolic blood pressure. OR indicates odds ratio; CI, confidence interval; PCI,
percutaneous coronary intervention; CABG, coronary artery bypass grafting; CHF, congestive heart
failure; and CAD, coronary artery disease.
*Creatinine ⬎2.0 mg/dL, calculated creatinine clearance ⬍30 mL/min, or need for chronic renal
dialysis.
†Compared with neither transient ST elevation nor ST depression.
‡Member of the Council of Teaching Hospitals.
and confound calculations for survival advantages for the
type of patients cared for by cardiologists, because such
patients usually have a lower burden of comorbidities.13,14
However, when measured and unmeasured confounding was
accounted for with advanced statistical techniques, cardiology care was not associated with a mortality reduction for
patients with acute MI but was associated with improved use
of evidence-based therapies.15 Conversely, the present results
and those from another study14 have shown that improved use
of evidence-based therapies among ACS and acute MI
patients partially explains differences in mortality by specialty. Furthermore, other studies have shown that higher
composite quality scores for the treatment of patients with
ACS and acute MI are associated with lower mortality rates,
but the proportion of patients with acute MI considered to be
ideal or eligible for guidelines-recommended therapies has
decreased over the last decade with an aging population that
has more comorbidities.16 –18 The challenge, therefore, is to
develop research techniques that more accurately delineate
how cardiology care and consultation between cardiologists
and generalists influence the outcomes and treatment patterns
of the increasingly complex population of patients with ACS
and acute MI.
Study Limitations
Several limitations were present with this analysis. First, we
did not collect detailed information regarding physician
treatment decisions for individual patients, so we could not
precisely determine how patient and hospital characteristics
influenced care patterns and influenced the disposition of
patients to cardiology and noncardiology services, even with
a dedicated chart abstraction project within the context of this
analysis. Second, documentation of medication contraindications may have varied by physician and hospital, which may
have confounded our analyses of medication use in “ideal”
candidates. Third, we did not collect contraindications to
cardiac catheterization, because these are not well-specified
in practice guidelines and often are dynamic as patients’
clinical characteristics change during the hospitalization.
Fourth, we did not survey participating hospitals to determine
whether differences existed in the quality improvement infrastructure or decision support systems for cardiology versus
noncardiology inpatient services (such as use of critical
treatment pathways, specialized nursing services, or electronic care prompts). Fifth, the mortality rate of the 472
patients excluded due to missing data on the specialty of the
primary inpatient service was 2-fold higher than the overall
Roe et al
TABLE 4.
Physician Specialty and ACS Treatment
1159
Treatment Patterns by Primary Inpatient Service*
Overall (n⫽55 994)
Cardiology (n⫽35 374)
Noncardiology (n⫽20 620)
Adjusted OR (95% CI)†
Aspirin
91.8 (n⫽52 399)
93.0 (n⫽33 789)
89.7 (n⫽18 610)
1.28 (1.17–1.39)
␤-Blocker
78.5 (n⫽51 128)
80.1 (n⫽32 713)
75.6 (n⫽18 415)
1.28 (1.20–1.36)
Heparin
83.4 (n⫽53 159)
86.1 (n⫽34 224)
78.4 (n⫽18 935)
1.56 (1.43–1.70)
Unfractionated
52.9
57.6
44.3
1.50 (1.42–1.60)
Low–molecular weight
37.2
35.8
39.7
0.90 (0.84–0.95)
GP IIb/IIIa inhibitor
37.7 (n⫽49 350)
45.0 (n⫽32 091)
24.1 (n⫽17 259)
2.11 (1.95–2.27)
Clopidogrel
42.5 (n⫽55 428)
47.8 (n⫽35 187)
33.3 (n⫽20 241)
1.58 (1.49–1.69)
Cardiac catheterization
72.7
81.4
57.8
2.55 (2.32–2.80)
Catheterization ⱕ48 h
51.5
61.2
34.9
2.25 (2.08–2.43)
PCI
41.7
49.2
28.9
1.86 (1.73–2.00)
PCI ⱕ48 h
30.0
37.1
17.8
2.06 (1.91–2.23)
CABG
13.3
14.0
12.1
1.13 (1.00–1.27)
Acute (ⱕ24 h) medications
Invasive procedures
Downloaded from http://circ.ahajournals.org/ by guest on August 10, 2017
Discharge therapies and interventions
Aspirin
90.8 (n⫽49 305)
92.5 (n⫽32 196)
87.5 (n⫽17 109)
1.37 (1.27–1.48)
␤-Blocker
83.9 (n⫽48 195)
84.5 (n⫽31 198)
82.8 (n⫽16 997)
1.13 (1.06–1.21)
ACE inhibitor‡
60.7 (n⫽38 497)
61.0 (n⫽24 355)
60.1 (n⫽14 142)
1.06 (1.01–1.12)
Lipid-lowering agent§
80.7 (n⫽33 354)
82.1 (n⫽22 367)
77.9 (n⫽10 987)
1.12 (1.03–1.22)
Clopidogrel
56.3 (n⫽51 966)
61.3 (n⫽33 446)
47.2 (n⫽18 520)
1.49 (1.40–1.59)
Smoking cessation counseling储
66.0 (n⫽15 454)
67.9 (n⫽10 724)
61.8 (n⫽4730)
1.20 (1.08–1.33)
Dietary recommendations
74.3 (n⫽53 695)
76.7 (n⫽34 249)
70.0 (n⫽19 446)
1.34 (1.24–1.45)
Cardiac rehabilitation referral
43.5 (n⫽47 534)
48.0 (n⫽30 368)
35.7 (n⫽17 166)
1.39 (1.28–1.50)
Nested percentages are not conditional, and percentages reported are in relation to the overall sample. GP indicates glycoprotein; PCI, percutaneous coronary
intervention.
*Among patients without documented contraindications. Data are expressed as percentages. Number of eligible patients for each medication or intervention is listed
in parentheses.
†Comparing cardiology with noncardiology care.
‡ACE inhibitor use reported only for patients with specific guidelines recommendations (ejection fraction ⬍40%, heart failure, diabetes mellitus, or hypertension).
§Lipid-lowering agent use reported only for patients with documented hyperlipidemia and/or measured LDL ⬎100 mg/dL.
储Among current/recent smokers.
have been long enough to fully evaluate the dissemination of
these new recommendations to all specialties.2
Another general limitation of large observational databases
such as CRUSADE is that data are frequently incomplete.
When certain covariates are not captured on all individuals, it
cannot be assumed that the pattern of missing data is
completely at random. In fact, we usually make an assump-
mortality rate of the analysis cohort, so exclusion of these
patients may have biased the results. Sixth, only tertiary
hospitals with full revascularization capabilities were included in the present analysis, so our results may not be
generalizable to nontertiary hospitals. Also, the timeline of
the present study spanned the release of the revisions to the
NSTE ACS guidelines (March 2002), so our analysis may not
TABLE 5.
In-Hospital Outcomes by Primary Inpatient Service
Death†
Overall
(n⫽55 994)
Cardiology
(n⫽35 374)
Noncardiology
(n⫽20 620)
Adjusted OR*
(95% CI)
4.1
3.2
5.7
0.80 (0.73–0.88)
Reinfarction
3.0
2.8
3.4
0.74 (0.65–0.84)
Congestive heart failure
8.7
7.1
11.5
0.96 (0.87–1.06)
Cardiogenic shock
2.7
2.5
3.0
1.08 (0.95–1.23)
Non-CABG RBC
transfusion
8.8
7.0
11.8
0.75 (0.69–0.82)
Data are expressed as percentages. RBC indicates red blood cell.
*Comparing cardiology with noncardiology care.
†Standardized mortality rates were 3.8% for cardiology vs 4.5% for noncardiology. Predicted
mortality rates were 3.4% for cardiology vs 5.2% noncardiology.
1160
Circulation
September 4, 2007
TABLE 6.
Acute Treatment Patterns by Propensity for Care to Be Provided by a Cardiology Inpatient Service*
Cardiology Care, Yes or No
Group 1 (n⫽11 194)
Group 2 (n⫽11 199)
Group 3 (n⫽11 199)
Group 4 (n⫽11 199)
Group 5 (n⫽11 197)
Yes
(n⫽4907)
No
(n⫽6287)
Yes
(n⫽6491)
No
(n⫽4708)
Yes
(n⫽7343)
No
(n⫽3856)
Yes
(n⫽7993)
No
(n⫽3206)
Yes
(n⫽8639)
No
(n⫽2558)
Aspirin
89.9
86.2
92.5
89.5
93.2
91.7
93.6
90.9
94.5
93.5
␤-Blocker
76.7
72.4
80.1
74.9
79.9
77.1
80.0
77.7
82.3
79.3
Heparin‡
81.1
72.9
84.4
77.4
86.1
80.5
87.2
82.2
89.1
85.2
GP IIb/IIIa inhibitor
27.2
12.5
38.7
21.0
45.8
28.5
48.9
30.6
53.8
38.4
Clopidogrel
37.6
26.1
44.6
32.1
47.5
36.3
52.0
36.5
52.5
44.0
Catheterization ⱕ48 h
39.3
18.2
56.6
33.4
64.4
42.7
67.0
44.6
68.9
54.5
Treatments†
All values are percentages. GP indicates glycoprotein.
*Patients categorized based on the propensity to receive care from a cardiology service into 5 equal groups ranging from those least likely to receive care from
a cardiology service (group 1) to those most likely to receive care from a cardiology service (group 5).
†Medications administered ⱕ24 h to patients without contraindications.
‡Includes unfractionated and low–molecular weight heparin.
Downloaded from http://circ.ahajournals.org/ by guest on August 10, 2017
tion that a variable is “missing at random,” meaning that a
variable’s absence is not a consequence of what would have
been observed for that variable, but it may be related to other
observed variables in the database. Although the GEE analysis we used has the capability of efficiently accounting for
clustering in a very large database, it cannot be guaranteed to
be unbiased. A weighted GEE analysis is sometimes recommended for data that have a missing-at-random pattern, but
this modification is technically not feasible in such a large,
complex database as CRUSADE with hundreds of possible
missing value patterns and a mixture of binary and continuous variables. However, in addition to the GEE analysis
presented in the present report, we performed a number of
sensitivity analyses to provide assurance that our results were
robust to the missing data.
Conclusions
We have demonstrated that patients with NSTE ACS primarily cared for by a cardiology service were younger and had
fewer comorbidities than those primarily cared for by a
noncardiology service, were more likely to receive evidencebased therapies, and had a lower risk of mortality. However,
our findings from contemporary US practice highlight the
difficulties of accurately determining the association of cardiology care with the treatment and outcomes of NSTE ACS
patients and suggest that studies with real-time, prospective
data collection are needed to further delineate the impact of
specialty care.
Sources of Funding
CRUSADE is funded by Schering-Plough Corporation. BristolMyers Squibb/Sanofi Pharmaceuticals Partnership provides additional funding support. Millennium Pharmaceuticals, Inc, Cambridge, Mass, also provided funding for this research.
Disclosures
Drs Roe and Smith serve as speakers for Millennium Pharmaceuticals,
Inc, Schering Corp, and Bristol-Myers Squibb/Sanofi-Aventis Pharmaceuticals Partnership. Drs Gibler, Ohman, Peterson, Roe, and Smith
have received research grants from Millennium Pharmaceuticals, Inc,
Schering Corp, and Bristol-Myers Squibb/Sanofi-Aventis Pharmaceuticals Partnership. The remaining authors report no conflicts.
References
1. Braunwald E, Antman EM, Beasley JW, Califf RM, Cheitlin MD,
Hochman JS, Jones RH, Kereiakes D, Kupersmith J, Levin TN, Pepine
CJ, Schaeffer JW, Smith EE III, Steward DE, Theroux P, Gibbons RJ,
Alpert JS, Eagle KA, Faxon DP, Fuster V, Gardner TJ, Gregoratos G,
Russell RO, Smith SC Jr. ACC/AHA guidelines for the management of
patients with unstable angina and non–ST-segment elevation myocardial
infarction: executive summary and recommendations: a report of the
American College of Cardiology/American Heart Association Task Force
on Practice Guidelines (Committee on Management of Patients With
Unstable Angina). Circulation. 2000;102:1193–1209.
2. Braunwald E, Antman EM, Beasley JW, Califf RM, Cheitlin MD,
Hochman JS, Jones RH, Kereiakes D, Kupersmith J, Levin TN, Pepine
CJ, Schaeffer JW, Smith EE III, Steward DE, Theroux P, Gibbons RJ,
Alpert JS, Faxon DP, Fuster V, Gregoratos G, Hiratzka LF, Jacobs AK,
Smith SC Jr; American College of Cardiology/American Heart Association Committee on the Management of Patients With Unstable Angina.
ACC/AHA 2002 guideline update for the management of patients with
unstable angina and non-ST-segment elevation myocardial infarction:
summary article: 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. 2002;40:1366 –1374.
3. Jollis JG, DeLong ER, Peterson ED, Muhlbaier LH, Fortin DF, Califf
RM, Mark DB. Outcome of acute myocardial infarction according to the
specialty of the admitting physician. N Engl J Med. 1996;335:
1880 –1887.
4. Ayanian JZ, Guadagnoli E, McNeil BJ, Cleary PD. Treatment and
outcomes of acute myocardial infarction among patients of cardiologists
and generalist physicians. Arch Intern Med. 1997;157:2570 –2576.
5. LaBresh KA, Ellrodt AG, Glicklich R, Liljestrand J, Peto R. Get with the
guidelines for cardiovascular secondary prevention: pilot results. Arch
Intern Med. 2004;164:203–209.
6. Mehta RH, Montoye CK, Gallogly M, Baker P, Blount A, Faul J,
Roychoudhury C, Borzak S, Fox S, Franklin M, Freundl M, Kline-Rogers
E, LaLonde T, Orza M, Parrish R, Satwicz M, Smith MJ, Sobotka P,
Winston S, Riba AA, Eagle KA; GAP Steering Committee of the
American College of Cardiology. Improving quality of care for acute
myocardial infarction: the Guidelines Applied in Practice (GAP) initiative. JAMA. 2002;287:1269 –1276.
7. Zhang H, Alexander JA, Luttrell J, O’Connor GT, Daley J, Paris M. Data
feedback and clinical process improvement in acute myocardial
infarction. Am Heart J. 2005;149:856 – 861.
8. Roe MT, Ohman EM, Pollack CV Jr, Peterson ED, Brindis RG, Harrington RA, Christenson RH, Smith SC Jr, Califf RM, Gibler WB.
Changing the model of care for patients with acute coronary syndromes.
Am Heart J. 2003;146:605– 623.
9. Liang KY, Zeger SL. Longitudinal data analysis using generalized linear
models. Biometrika. 1986;73:13–22.
Roe et al
10. Rosenbaum PR, Rubin DB. The central role of the propensity score in
observational studies for causal events. Biometrika. 1983;70:41–55.
11. Willison DJ, Soumerai SB, McLaughlin TJ, Gurwitz JH, Gao X, Guadagnoli E, Pearson S, Hauptman P, McLaughlin B. Consultation between
cardiologists and generalists in the management of acute myocardial
infarction: implications for quality of care. Arch Intern Med. 1998;158:
1778 –1783.
12. Smetana SW, Landon BE, Bindman AB, Burstin H, Davis RB, Tija J,
Rich EC. A comparison of outcomes resulting from generalist vs. specialist care for a single discrete medical condition: a systematic review
and methodologic critique. Arch Intern Med. 2007;167:10 —-20.
13. Frances CD, Go AS, Dauterman KW, Deosaransingh K, Jung DL, Gettner
S, Newman JM, Massie BM, Browner WS. Outcome following acute
myocardial infarction: are differences among physician specialties the
result of quality of care or case mix? Arch Intern Med. 1999;159:
1429 –1436.
14. Chen J, Radford MJ, Wang Y, Krumholz HM. Care and outcomes of
elderly patients with acute myocardial infarction by physician specialty:
Physician Specialty and ACS Treatment
15.
16.
17.
18.
1161
the effects of comorbidity and functional limitations. Am J Med. 2000;
108:460 – 469.
Frances CD, Shlipak MG, Noguchi H, Heidenreich PA, McClellan M.
Does physician specialty affect the survival of elderly patients with
myocardial infarction? Health Serv Res. 2000;35:1093–1116.
Peterson ED, Roe MT, Mulgund J, DeLong ER, Lytle BL, Brindis RG,
Smith SC Jr, Pollack CV Jr, Newby LK, Harrington RA, Gibler WB,
Ohman EM. Association between hospital process performance and
outcomes among patients with acute coronary syndromes. JAMA. 2006;
295:1912–1920.
Bradley EH, Herrin J, Elbel J, McNamara RL, Magid DL, Nallamothu
BK, Wang Y, Normand SLT, Spertus JA, Krumholz HM. Hospital quality
for acute myocardial infarction: correlation among process measures and
relationship with short-term mortality. JAMA. 2006;296:72–78.
Masoudi FA, Foody JM, Havranek EP, Wang Y, Radford MJ, Allman
RM, Gold J, Wiblin RT, Krumholz HM. Trends in acute myocardial
infarction in 4 U.S. states between 1992 and 2001: clinical characteristics,
quality of care, and outcomes. Circulation. 2006;114:2806 –2814.
CLINICAL PERSPECTIVE
Downloaded from http://circ.ahajournals.org/ by guest on August 10, 2017
Previous studies have demonstrated differences in the treatment of patients with acute coronary syndromes by physician
specialty, but the impact of cardiology specialty care on contemporary treatment patterns has not been studied. We
evaluated 55 994 patients with non–ST-segment elevation acute coronary syndromes (ischemic ST-segment changes and/or
positive cardiac markers) included in the CRUSADE Quality Improvement Initiative from January 2001 through
September 2003 at 301 tertiary US hospitals with full revascularization capabilities. Approximately two thirds of patients
were primarily cared for by a cardiology service, and these patients had lower-risk clinical characteristics and more
commonly received guidelines-recommended acute (ⱕ24 hours) medications, invasive cardiac procedures, and discharge
medications and lifestyle interventions than patients primarily cared for on a noncardiology service. Although the adjusted
risk of in-hospital mortality was lower with care provided by a cardiology service, accounting for differences in the use
of acute medications and invasive procedures partially attenuated this adjusted mortality difference. The present analysis
highlights the difficulties in accurately determining how specialty care is associated with clinical outcomes for patients with
acute coronary syndromes and suggests that novel methodologies for evaluating the influence of specialty care on the
treatment and outcomes of acute coronary syndrome patients need to be developed.
Influence of Inpatient Service Specialty on Care Processes and Outcomes for Patients
With Non−ST-Segment Elevation Acute Coronary Syndromes
Matthew T. Roe, Anita Y. Chen, Rajendra H. Mehta, Yun Li, Ralph G. Brindis, Sidney C.
Smith, Jr, John S. Rumsfeld, W. Brian Gibler, E. Magnus Ohman and Eric D. Peterson
Downloaded from http://circ.ahajournals.org/ by guest on August 10, 2017
Circulation. 2007;116:1153-1161; originally published online August 20, 2007;
doi: 10.1161/CIRCULATIONAHA.107.697003
Circulation is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231
Copyright © 2007 American Heart Association, Inc. All rights reserved.
Print ISSN: 0009-7322. Online ISSN: 1524-4539
The online version of this article, along with updated information and services, is located on the
World Wide Web at:
http://circ.ahajournals.org/content/116/10/1153
Data Supplement (unedited) at:
http://circ.ahajournals.org/content/suppl/2007/08/20/CIRCULATIONAHA.107.697003.DC1
http://circ.ahajournals.org/content/suppl/2007/08/20/CIRCULATIONAHA.107.697003.DC2
Permissions: Requests for permissions to reproduce figures, tables, or portions of articles originally published
in Circulation can be obtained via RightsLink, a service of the Copyright Clearance Center, not the Editorial
Office. Once the online version of the published article for which permission is being requested is located,
click Request Permissions in the middle column of the Web page under Services. Further information about
this process is available in the Permissions and Rights Question and Answer document.
Reprints: Information about reprints can be found online at:
http://www.lww.com/reprints
Subscriptions: Information about subscribing to Circulation is online at:
http://circ.ahajournals.org//subscriptions/