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Do Subspecialists Working Outside of Their Specialty Provide Less Efficient and Lower-Quality Care to Hospitalized Patients Than Do Primary Care Physicians?
Scott R. Weingarten, MD, MPH;
Lynne Lloyd, MBA;
Chiun-Fang Chiou, PhD;
Glenn D. Braunstein, MD
Arch Intern Med. 2002;162:527-532.
ABSTRACT
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Background Studies show that subspecialists can provide better quality care than
primary care physicians when working within their subspecialty for patients
with some medical conditions. However, many subspecialists care for patients
outside of their chosen subspecialty. The present study compared the quality
of care provided by subspecialists practicing outside of their specialty,
general internists, and subspecialists practicing within their specialty.
Methods The severity-adjusted mortality rate and the severity-adjusted length
of stay were used as indexes of quality of care. Data from 5112 hospital admissions
(301 different physicians) for community-acquired pneumonia, acute myocardial
infarction, congestive heart failure, or upper gastrointestinal hemorrhage
at 6 hospitals in the greater Cleveland, Ohio, area were used in this study.
The data were severity adjusted with the CHOICE Severity of Illness System.
Results Subspecialists working outside of their subspecialty cared for 25% of
hospitalized patients. When comparing patients cared for by subspecialists
practicing outside of their subspecialty, severity-adjusted lengths of stay
were longer for patients with congestive heart failure (23% longer; 95% confidence
interval [CI], 15%-32%), upper gastrointestinal hemorrhage (22% longer; 95%
CI, 7%-39%), and community-acquired pneumonia (14% longer; 95% CI, 5%-24%)
than for patients cared for by subspecialists practicing within their subspecialty.
Patients also had a slightly higher hospital mortality rate when cared for
by subspecialists practicing outside of their specialty than by subspecialists
practicing within their subspecialty (mortality rate odds ratio, 1.46; P = .047). In addition, patients cared for by subspecialists
practicing outside of their subspecialty had longer lengths of stay, and prolongations
of stay were observed for patients with congestive heart failure (16% longer;
95% CI, 8%-26%), upper gastrointestinal hemorrhage (15% longer; 95% CI, 2%-30%),
and community-acquired pneumonia (18% longer; 95% CI, 9%-28%) than patients
cared for by general internists.
Conclusions Subspecialists commonly care for patients outside of their subspecialty,
despite the fact that their patients may have longer lengths of stay than
those cared for by subspecialists practicing within their specialty or by
general internists. In addition, such patients may have slightly higher mortality
rates than those cared for by subspecialists practicing within their subspecialty.
INTRODUCTION
THERE HAS BEEN significant discussion and debate regarding the role
of subspecialists and primary care physicians in providing care to patients
with diverse medical conditions.1-7
Several studies have reported that subspecialists have more up-to-date medical
knowledge and provide better quality of care than primary care physicians
when caring for patients with conditions within their chosen specialty (eg,
cardiologists providing care to patients with congestive heart failure).1 For example, when patients with acute myocardial infarction,
acute nonhemorrhagic stroke, and asthma are cared for by subspecialists, they
may have better outcomes than when they are cared for by general internists.1 Moreover, a survey8
of primary care physicians showed that primary care physicians believed that
the scope of conditions that they treat had increased significantly, and that
24% believed that the scope of care that they were expected to provide was
greater than it should be.
Recent studies9-11
have suggested that there may be a surplus of subspecialists, as determined
by projecting physician manpower needs from managed care subspecialty requirements
to a population of patients. A possible surplus of subspecialists may result
in some subspecialists expanding the scope of care that they provide and treating
conditions outside of their chosen specialty.3
Although many studies have compared subspecialists practicing within
their chosen specialty with primary care physicians, few have examined the
quality and efficiency of care provided by subspecialists practicing outside
of their specialty. Using a valid severity of illness model,12-13
the present study compared the quality of care provided by subspecialists
caring for patients outside of their specialty with that provided by general
internists and by subspecialists caring for patients within their specialty.
SUBJECTS AND METHODS
OUTCOME MEASURES
The primary outcome measures used to indicate the quality of care that
patients received were the severity-adjusted mortality rate and hospital length
of stay (LOS). The models were constructed based on patients' demographic
and clinical data.
DATA SOURCE
Six hospitals in the greater Cleveland area, in northeast Ohio, provided
information on their physician subspecialties and patients cared for by these
physicians to this study. All of these hospitals were members of the Cleveland
Health Quality Choice Coalition Consortium.12-14
Among them, 1 is a rural hospital and 5 are community hospitals. Of the 6
hospitals, only 1 had a hospitalist program, and none had an internal medicine
training program, family practice training program, or full-time faculty.
Two of the hospitals were part of a health care system and are coded as a
single hospital (hospital 4) (Table 1).
The Cleveland Health Quality Choice program was a regional effort of health
care organizations to compare and improve hospital performance.12-14
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Table 1. Observed Mortality Rates From Different Hospitals*
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Lengths of stay and mortality rates for patients with acute myocardial
infarction, congestive heart failure, upper gastrointestinal hemorrhage, or
community-acquired pneumonia were examined in this study.
Data, including sociodemographic variables, admission source, medications,
medical history, vital signs, selected variables from the physical examination,
results of laboratory tests, electrocardiographic findings, echocardiographic
findings, and do not resuscitate status, were abstracted from the medical
record of each patient by medical record technicians. There were explicit
protocols for data abstraction, double keystroke entry, identification of
out-of-range variables, and independent verification of data quality at each
hospital.
PHYSICIANS AND PHYSICIAN CLASSIFICATION
The primary physician for selected patients was obtained independently
by each hospital participating in this study. The selected physician was the
attending physician of record in each case. The subspecialty status of physicians
was verified by reviewing information supplied by each hospital (medical staff
office), information provided on the American Medical Association and American
Board of Internal Medicine Web sites, and other available information on physician
subspecialty.15
Physicians were classified as those practicing within their subspecialty,
those practicing outside of their subspecialty, general internists, or family
practitioners. For community-acquired pneumonia, physicians were classified
as practicing within the specialty if they were trained in infectious diseases
or pulmonary medicine. For upper gastrointestinal hemorrhage, physicians were
classified as practicing within the specialty if they were gastroenterologists.
For congestive heart failure or acute myocardial infarction, physicians were
classified as practicing within the subspecialty if they were cardiologists.
PATIENTS AND PATIENT CLASSIFICATION
Patients were classified based on the International
Classification of Diseases, Ninth Revision, Clinical Modification,
principal diagnosis code. Only information on patients who were hospitalized
in the 6 hospitals for acute myocardial infarction, congestive heart failure,
upper gastrointestinal hemorrhage, or community-acquired pneumonia between
January 1, 1997, and December 1, 1997, was used in this study. Data of patients
who were younger than 18 years or transferred from other acute-care hospitals
were excluded. Patients may have been hospitalized more than one time, and
each hospitalization was considered separately.
SEVERITY ADJUSTMENT AND THE CHOICE SEVERITY OF ILLNESS SYSTEM
The CHOICE Severity of Illness System was developed by the Cleveland
Health Quality Choice program.12-13
The system has multivariate models that were developed separately for each
diagnosis. These models enable us to predict the mortality (0%-100%) and expected
LOS (in days) for patients with community-acquired pneumonia, congestive heart
failure, upper gastrointestinal hemorrhage, or acute myocardial infarction.
These models were built from the demographic and clinical variables ascertained
within the first 48 hours of hospitalization and were validated by the CHOICE
Severity of Illness System in several steps. The initial models were derived
from factors that independently contributed to the risk of death or LOS (P<.01) in logistic or linear regression models. Length
of stay data were log transformed because the data were heavily skewed. The
LOS models excluded patients who died in the hospital or were transferred
to other hospitals.
The performance of the mortality models was examined by the receiver
operating characteristic curve and calibration was examined by the Hosmer-Lemeshow
goodness-of-fit test,16 while the performance
of the LOS models was assessed by the value of R2 and by analysis of residuals. Models used in this study were those
reestimated and examined using the larger data set. The receiver operating
characteristic curve areas and R2 were
similar among the diagnoses studied. The receiver operating characteristic
curve areas for mortality and the R2 for
LOS for the diagnoses are as follows: acute myocardial infarction, 0.89 and
0.19, respectively; congestive heart failure, 0.85 and 0.14, respectively;
pneumonia, 0.88 and 0.25, respectively; and upper gastrointestinal hemorrhage,
0.91 and 0.23, respectively. Performance of the model was also similar in
different types of hospitals. We used our data to calculate the area under
the receiver operating characteristic curves, and found similar findings.
STATISTICAL ANALYSIS
Differences in patients' demographics and outcomes between physician
groups were analyzed: differences in patients' age, LOS, and risk of death
(severity-adjusted mortality rate) were examined using a Wilcoxon nonparametric
test, while those in sex, race, and mortality were examined using a  2 test. Multivariate analyses were also performed to analyze differences
in patients' outcomes of physician groups and to adjust patient outcomes for
patient severity of illness. Individual patient severity of illness was first
determined based on each patient's demographics (eg, age) and clinical factors
(eg, coexisting diseases, laboratory results, and vital signs) using the CHOICE
Severity of Illness System, assuming no unmeasured selection effects associated
with mortality rates and LOS due to the limitation of available data.
To estimate the magnitude of the difference in severity-adjusted LOS
between the physician groups, a linear regression analysis was used. A dummy
variable for each physician group was used within the model to ascertain the
differences between each group relative to one another. Because LOS is log
transformed, the antilog of the coefficient in the linear regression model
represents the ratio of severity-adjusted LOS between each physician group
and the reference group. If the coefficient is 0.1, for example, the ratio
of severity-adjusted LOS between a specific physician group and the reference
group is 1.26 (e0.1). It can also be interpreted
that the severity-adjusted LOS of the specific physician group is 26% higher
than the one of the reference group.
To analyze differences in mortality rates, logistic regression was used
with a dummy variable to ascertain the differences in mortality rates of physician
groups. With a certain formula of antilog transformation, the variable estimate
for each dummy variable in the logistic regression model measures the change
in the mortality rate between each physician group and the reference group.
Confidence intervals were then calculated for each estimate to reflect
the variation within the data and the statistical significance of the findings. P<.05 was considered statistically significant. SAS
statistical software was used for all of the statistical analyses.17
RESULTS
PATIENT DEMOGRAPHICS AND CLASSIFICATION
There were a total of 6485 patient hospital admissions that were potentially
eligible for the study. Of these patient hospital admissions, 1373 included
patients who were not clearly identified as being primarily treated by an
internal medicine subspecialist, a general internist, or a family practitioner.
The remaining 5112 patient admissions were enrolled in the study. Among them,
1143 patients (22%) had an acute myocardial infarction, 610 (12%) had an upper
gastrointestinal hemorrhage, 1946 (38%) had congestive heart failure, and
1413 (28%) had community-acquired pneumonia.
When patients were classified according to the type of physician who
provided their care, as seen in Table 2, a total of 1776 patients (35%) were treated by a physician practicing
within his or her specialty, 1083 (21%) were treated by an internist without
an identified specialty, 990 (19%) were treated by a family practitioner,
and 1263 (25%) were treated by a subspecialist practicing outside of his or
her specialty. There were 301 different physicians.
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Table 2. Demographics of Patients Treated by Different Types of Physicians*
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The mean ± SD age of the patients was 72.2 ± 13.9 years,
93% were white, and 51% were men. About 72% of the patients had Medicare insurance,
and 23% had commercial insurance. The mean ± SD LOS was 5.6 ±
3.9 days.
IN-HOSPITAL MORTALITY
The mean in-hospital mortality was 5.4%. The mean severity-adjusted
mortality was 5.5%. Mortality rates for each hospital are listed in Table 1. Patients cared for by subspecialists
practicing outside of their specialty had higher mortality rates than those
cared for by subspecialists practicing within their specialty (P = .047) (analysis 1 in Table 3). There were no significant differences in the mortality rates
when comparing patients cared for by general internists with those cared for
by subspecialists practicing outside of their specialty (P = .17) or when comparing patients cared for by general internists
with those cared for by subspecialists practicing within their subspecialty
(P = .65) (analysis 2 in Table 3). Similar results were found for the severity-adjusted mortality
rate. Too few patients with an upper gastrointestinal hemorrhage died to compare
mortality rates by physician types.
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Table 3. Comparison of Patient Mortality Rates Among Physician Types*
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LENGTH OF STAY
The mean patient hospital LOS was 5.7 days. The mean LOS was 5.5 days
for general internists' patients, 5.6 days for family practitioners' patients,
5.2 days for patients cared for by subspecialists practicing within their
specialty, and 6.6 days for those cared for by subspecialists practicing outside
of their specialty. The severity-adjusted LOS was longer for patients treated
by subspecialists practicing outside of their specialty than for those cared
for by subspecialists practicing within their specialty (Table 4). These differences were observed for patients with acute
myocardial infarction, congestive heart failure, gastrointestinal hemorrhage,
and pneumonia. In addition, patients cared for by subspecialists practicing
outside of their subspecialty had longer LOSs than those treated by general
internists (Table 4).
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Table 4. Comparison of Severity-Adjusted Lengths of Stay Among Physician
Types*
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COMMENT
This study demonstrated that subspecialists caring for patients outside
of their specialty may provide less efficient care, as evidenced by longer
LOSs, than either subspecialists practicing within their subspecialty or general
internists. In addition, patients cared for by physicians practicing outside
of their specialty may have slightly higher mortality rates than those cared
for by subspecialists practicing within their specialty. The odds ratio for
subspecialists caring for patients outside of their subspecialty when compared
with subspecialists caring for patients within their subspecialty was 1.46
(P = .047). Patients cared for by physicians outside
of their specialty also had 19% longer LOSs for the total population of patients,
and significantly longer LOSs for patients with congestive heart failure,
upper gastrointestinal hemorrhage, and community-acquired pneumonia. These
differences suggest that subspecialists practicing outside of their specialty
may provide less efficient care and possibly lower-quality care when compared
with physicians providing care within their subspecialty.
When comparing the mortality rates of patients treated by physicians
practicing outside of their specialty with those of patients cared for by
general internists, there were no statistically significant differences. However,
LOSs for patients cared for by subspecialists practicing outside of their
specialty were 17% longer than those of patients cared for by general internists,
and prolongations of stay were observed for patients with congestive heart
failure, upper gastrointestinal hemorrhage, and community-acquired pneumonia.
Therefore, LOSs were shorter when patients were treated by general internists
rather than subspecialists practicing outside of their specialty.
This study is one of few that have examined the potential implications
of having subspecialists care for patients outside of their subspecialty.
The strengths of the present study include the following: (1) it had more
than 5112 patients treated at 6 different hospitals and (2) a severity-of-illness
adjustment was performed to minimize the chance that differences in LOSs and
mortality rates could be attributed to differences in patient severity of
illness.12-13
This study also has limitations. First, teams of physicians often care
for hospitalized patients, including different subspecialists. It can be difficult
to attribute the efficiency or quality of care to a single physician or type
of physician. However, the identified physician in the study was the primary
attending physician of record as coded by the hospital. Although we attempted
to control for the number of patients with a particular condition treated
by a physician, we only had access to the information of patients treated
in the hospitals that participated in this study. It is possible that a physician
might have admitted patients to hospitals other than these 6. Therefore, the
real volume of patients treated by physicians in this study might be higher
than what was measured. Information regarding the volume of patients treated
by different types of physicians could be inaccurate and, thus, was not used
as a variable in the analyses. In addition, there were some differences in
demographics between those patients cared for by general internists, subspecialists
practicing within their subspecialty, and subspecialists practicing outside
of their subspecialty. However, patients' LOSs and mortality rates were adjusted
for patient severity of illness, which should account for any difference that
patient severity of illness or age might have had on LOS. In addition, the
LOS may impact hospital mortality rates. Finally, this study used the patient
as the unit of analysis rather than the hospital or the physician.
The observed differences in LOS may demonstrate that physicians caring
for patients outside of their chosen specialty are less familiar with patients
with these conditions because volume-outcome relationships have been shown
for many conditions in medicine, and subspecialists practicing outside of
their subspecialty may be a marker for low patient volume. Moreover, subspecialists
frequently care for patients outside of their chosen subspecialty, because
25% of patients were cared for by subspecialists practicing outside of their
subspecialty. A recent study8 showed that many
primary care physicians believe that the scope of conditions that they are
expected to treat is greater than it ought to be. Because many subspecialists
may perform primary care and treat hospitalized patients outside of their
subspecialty, it is possible that subspecialists may have similar concerns
that the scope of conditions that they treat outside of their subspecialty
is greater than it should be.
In conclusion, subspecialists commonly care for patients outside of
their subspecialty. Patients cared for by subspecialists practicing outside
of their subspecialty had longer LOSs and possibly higher mortality rates
than those cared for by subspecialists practicing within their subspecialty;
they also had longer LOSs when compared with those cared for by general internists.
If patients are cared for by subspecialists practicing outside of their specialty,
their LOSs, and possibly even mortality rates, may be higher than those of
patients cared for by subspecialists practicing within their subspecialty.
AUTHOR INFORMATION
Accepted for publication July 16, 2001.
We thank Dwain Harper, DO, for his assistance with this study.
Corresponding author and reprints: Scott R. Weingarten, MD, MPH,
Zynx Health, Inc, Cedars-Sinai Health System, 9100 Wilshire Blvd, Suite 655E,
Beverly Hills, CA 90212 (e-mail: weingarten{at}zynx.com).
From the Department of Health Services Research (Zynx Health, Inc),
Cedars-Sinai Health System, Beverly Hills, Calif (Drs Weingarten and Chiou);
and the Department of Medicine, University of California, Los Angeles, UCLA
School of Medicine (Drs Weingarten and Braunstein). Ms Lloyd is an independent
consultant.
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