Instability on Hospital Discharge and the Risk of Adverse Outcomes in
Patients With Pneumonia
Author Information
<http://archinte.ama-assn.org/issues/v162n11/rfull/#aainfo> Ethan A. Halm,
MD, MPH; Michael J. Fine, MD, MSc; Wishwa N. Kapoor, MD, MPH; Daniel E.
Singer, MD; Thomas J. Marrie, MD; Albert L. Siu, MD, MSPH
Background Investigating claims that patients are being sent home from the
hospital "quicker and sicker" requires a way of objectively measuring
appropriateness of hospital discharge.
Objective To define and validate a simple, usable measure of clinical
stability on discharge for patients with community-acquired pneumonia.
Methods Information on daily vital signs and clinical status was collected
in a prospective, multicenter, observational cohort study. Unstable factors
in the 24 hours prior to discharge were temperature greater than 37.8°C,
heart rate greater than 100/min, respiratory rate greater than 24/min,
systolic blood pressure lower than 90 mm Hg, oxygen saturation lower than
90%, inability to maintain oral intake, and abnormal mental status. Outcomes
were deaths, readmissions, and failure to return to usual activities within
30 days of discharge.
Results Of the 680 patients, 19.1% left the hospital with 1 or more
instabilities. Overall, 10.5% of patients with no instabilities on discharge
died or were readmitted compared with 13.7% of those with 1 instability and
46.2% of those with 2 or more instabilities (P<.003). Instability on
discharge (1 unstable factor) was associated with higher risk-adjusted rates
of death or readmission (odds ratio [OR], 1.6; 95% confidence interval [CI],
1.0-2.8) and failure to return to usual activities (OR, 1.5; 95% CI,
1.0-2.4). Patients with 2 or more instabilities had a 5-fold greater
risk-adjusted odds of death or readmission (OR, 5.4; 95% CI, 1.6-18.4).
Conclusions Instability on discharge is associated with adverse clinical
outcomes. Pneumonia guidelines and pathways should include objective
criteria for judging stability on discharge to ensure that efforts to
shorten length of stay do not jeopardize patient safety.
Arch Intern Med. 2002;162:1278-1284
IOI10363
OVER THE past 15 years, hospital length of stay has fallen dramatically.
Studies assessing the impact of the prospective payment system on hospital
care of Medicare beneficiaries in the 1980s indicated that this shortening
length of stay was accompanied by a 43% relative increase in patients being
sent home clinically unstable with unresolved medical issues. 1
<http://archinte.ama-assn.org/issues/v162n11/rfull/#r1> , 2
<http://archinte.ama-assn.org/issues/v162n11/rfull/#r2> This was worrisome
because Medicare beneficiaries who were discharged unstable had a 60%
greater odds of death. 2
<http://archinte.ama-assn.org/issues/v162n11/rfull/#r2> This has been
called the "quicker and sicker" phenomenon. The widespread diffusion of
managed care throughout the 1990s has resulted in even more dramatic
declines in the length of stay for many common conditions, including
pneumonia. 3 <http://archinte.ama-assn.org/issues/v162n11/rfull/#r3> With
patients needing to be sicker than ever to justify admission and the
duration of hospital stays becoming even shorter, many providers, patients,
and policy makers have expressed concern that patients are being sent home
quicker and sicker than ever. 4-8
<http://archinte.ama-assn.org/issues/v162n11/rfull/#r4>
Investigating these claims in an unbiased fashion requires a way of
objectively measuring appropriateness of hospital discharge. In general,
federal and state legislative and regulatory approaches have focused on the
duration of hospital stay. 6
<http://archinte.ama-assn.org/issues/v162n11/rfull/#r6> Unfortunately,
since the landmark RAND study in the early 1990s, 2
<http://archinte.ama-assn.org/issues/v162n11/rfull/#r2> there have been
few, if any, clinical indicators proposed that empirically assess readiness
for hospital discharge. The RAND measure of instability on discharge, which
was developed in the 1980s, has the limitations of not including some
factors that are now considered core vital signs (such as oxygen
saturation), while including others that are no longer thought to have major
clinical significance (eg, premature ventricular contractions).
In a previous study, we developed a pneumonia-specific measure of clinical
stability that was based on a smaller number of key clinical variables,
included key variables such as oxygenation, and used vital sign cut points
that more closely corresponded to traditional thresholds than the original
RAND criteria (eg, heart rate is stable if 100/min vs RAND cut point of
<130/min). 2 <http://archinte.ama-assn.org/issues/v162n11/rfull/#r2> , 9
<http://archinte.ama-assn.org/issues/v162n11/rfull/#r9> , 10
<http://archinte.ama-assn.org/issues/v162n11/rfull/#r10> Our definition of
clinical stability was based on temperature, heart rate, blood pressure,
respiratory rate, oxygenation, mental status, and ability to maintain oral
intake. These factors have been identified by physicians as important for
deciding when to switch from intravenous to oral antibiotics 10
<http://archinte.ama-assn.org/issues/v162n11/rfull/#r10> and how to judge
appropriateness for hospital discharge. 11
<http://archinte.ama-assn.org/issues/v162n11/rfull/#r11> Once someone with
pneumonia was stable according to this disease-specific definition of
stability, the risk of serious clinical deterioration during the rest of
their hospital stay was 1% or less, even in the sickest subgroup of
patients. 9 <http://archinte.ama-assn.org/issues/v162n11/rfull/#r9>
From a patient safety perspective, it is equally important to assess the
relationship between stability on discharge and posthospital outcomes. Among
patients with pneumonia, the rates of death, readmission, and delayed return
to usual activities in the 30 days after leaving the hospital are
substantial. 12-14 <http://archinte.ama-assn.org/issues/v162n11/rfull/#r12>
The specific aims of the present study were to (1) describe rates and types
of instability on discharge, (2) examine associations between instability on
discharge and a range of posthospital outcomes, and (3) determine if
instability on discharge influences the risk of adverse events even after
adjusting for other important prognostic factors and potential confounders.
Our hypothesis was that the greater the number of instabilities on
discharge, the greater the risk of adverse outcomes following discharge.
SUBJECTS AND METHODS
STUDY POPULATION AND SITES
The present study was part of the Pneumonia Patient Outcomes Research Team
(PORT) cohort study (a prospective, multicenter, observational study of
outcomes in hospitalized and ambulatory patients with community-acquired
pneumonia). Complete details about the Pneumonia PORT cohort study have been
described previously. 12
<http://archinte.ama-assn.org/issues/v162n11/rfull/#r12> , 15
<http://archinte.ama-assn.org/issues/v162n11/rfull/#r15> Study inclusion
criteria were (1) age 18 years or older, (2) symptoms of acute pneumonia,
and (3) radiographic evidence of pneumonia. Patients were excluded if they
were human immunodeficiency virus positive or had been hospitalized within
10 days.
As part of a substudy on all hospitalized patients enrolled in the Pneumonia
PORT cohort study, detailed daily inpatient data were collected during 2
consecutive sampling periods. During period 1 (October 15, 1991, through May
14, 1993), medical record review was done on consecutive low-risk patients
(<4% predicted risk of death). During period 2 (May 15, 1993, through March
31, 1994), medical record review was done on all consecutive hospitalized
patients regardless of mortality risk. This strategy captured 680 patients
who were discharged alive from the overall Pneumonia PORT cohort study of
1343 inpatients. Because we oversampled low-risk patients during period 1,
the 680 patients in the detailed daily assessment cohort we report on in the
present study were younger (mean age, 61 vs 74 years) and had lower
predicted 30-day mortality (2% vs 6%) than patients in the overall Pneumonia
PORT study who did not have daily medical record review. The mortality rates
for all inpatients enrolled during study periods 1 and 2 (prior to exclusion
of high risk cases in period 1) were the same (7% vs 6%). There were no
differences in the mortality rates for patients entered in the 2 sampling
periods when we stratified by admission mortality risk class as defined by
the Pneumonia Severity Index (PSI), a multivariable logistic model of
short-term mortality described below. 15
<http://archinte.ama-assn.org/issues/v162n11/rfull/#r15>
The participating inpatient sites (and number of patients enrolled) were the
University of Pittsburgh Medical Center and St Francis Medical Center,
Pittsburgh, Pa (214 and 59, respectively); the Massachusetts General
Hospital, Boston (243); and the Victoria General Hospital, Halifax, Nova
Scotia (164). The study was conducted from October 15, 1991, through March
31, 1994, and was approved by the institutional review board of all
participating institutions.
BASELINE DATA, DAILY MEASUREMENTS, AND DEFINITIONS OF STABILITY
Information on sociodemographic characteristics, initial pneumonia severity,
comorbid conditions, vital signs, mental status, ability to eat, physical
examination findings, laboratory results, and chest radiography findings was
collected on admission. Pneumonia severity was assessed usingthe PSI, which
is a well-validated, disease severity classification using a 20-variable
composite score based on age, sex, nursing home residence, 5 comorbid
illnesses, vital signs on admission, mental status, and 7 laboratory and
chest radiography findings from presentation. 15
<http://archinte.ama-assn.org/issues/v162n11/rfull/#r15> Class I patients
have the least severe disease, and class V patients, the most severe
disease. The PSI has been shown to be a robust predictor of a full range of
30-day outcomes including mortality, readmissions, and return to usual
activities. 12 <http://archinte.ama-assn.org/issues/v162n11/rfull/#r12> ,
15-18 <http://archinte.ama-assn.org/issues/v162n11/rfull/#r15>
The highest temperature, heart rate, and respiratory rate and the lowest
systolic blood pressure, oxygen saturation, and PaO2 of each hospital day
was abstracted from the medical record. Nearly all temperatures on the
hospital ward were measured orally. The patient's mental status and ability
to eat each day were also recorded. A patient was considered to be stable on
discharge if their temperature, heart rate, respiratory rate, systolic blood
pressure, oxygenation, ability to eat, and mental status were all stable in
the 24-hour period prior to discharge. 9
<http://archinte.ama-assn.org/issues/v162n11/rfull/#r9> Stable values for
vital signs were selected prior to analysis based on the clinical literature
and common clinical practice. 2
<http://archinte.ama-assn.org/issues/v162n11/rfull/#r2> , 10
<http://archinte.ama-assn.org/issues/v162n11/rfull/#r10> The stability cut
point for temperature was 37.8°C or lower; heart rate, 100/min or lower;
systolic blood pressure, 90 mm Hg or higher; and respiratory rate, 24/min or
lower.
Oxygenation was considered stable if the oxygen saturation rate was 90% or
higher or the PaO2 was 60 mm Hg or higher and a patient was not receiving
mechanical ventilation or supplemental oxygen by face mask. We did not know
the oxygen flow rate for patients who received supplemental oxygen by nasal
prongs. Therefore, we regarded these patients to have stable oxygenation if
they had an oxygen saturation rate of 95% or higher. If oxygenation was not
measured on a given day, the value of the most recent assessment was used.
The mean last day that oxygen saturation was measured was 6.4 days. Patients
who used home oxygen prior to admission were not considered to have unstable
oxygenation on discharge.
Mental status was considered stable if the patient was either normal or, for
those with chronic dementia, back to baseline. Patients who were able to eat
(or resumed long-term tube feeding) were counted as having stable eating
status. The number of instabilities on discharge was defined as the number
of vital sign and clinical status factors that did not meet the above
criteria in the 24 hours prior to leaving the hospital.
CLINICAL OUTCOMES
All patients received a standard telephone follow-up call 30 days after
discharge to ascertain survival, readmissions, and return to their usual
activities. Any death or readmission within 30 days of discharge was
considered a major event. Patients who died after being readmitted were only
counted as having 1 major event. We constructed this composite outcome
because we believed that either adverse outcome could be a marker of a
patient being sent home prior to being clinically ready.
STATISTICAL ANALYSES
Means plusmnSDs are presented for normal data and medians with interquartile
ranges (IQRs) for nonnormal data. We used logistic regression to examine the
association between the number of instabilities on discharge and the risk of
death, readmission, major events, and failure to return to usual activities
within 30 days of hospital discharge. Candidate variables entered into the
multivariable models were PSI score, do not resuscitate (DNR) status, number
of comorbid conditions, presence of chronic obstructive pulmonary disease,
use of home oxygen, discharge to a skilled nursing home facility, discharge
against medical advice, and receipt of posthospital home health services.
Covariates that were significant at the 2-tailed level of P<.05 were
retained in the final multivariable models. All other analyses also used
2-tailed significance levels of P<.05 and were conducted with SAS
statistical software (version 6.12; SAS Institute, Cary, NC). Using the
Kaplan-Meier and Cox proportional hazards methods, we found similar
associations between instabilities on discharge and the time to death,
readmission, or failure to return to usual activities within 30 days as
those produced by the primary logistic regression models we report herein.
The sensitivity, specificity, positive predictive value, and negative
predictive value of 2 definitions of instability on discharge to identify
death or readmission within 30 days were calculated in the standard fashion.
19 <http://archinte.ama-assn.org/issues/v162n11/rfull/#r19>
RESULTS
PATIENT CHARACTERISTICS
Characteristics of the study subjects are summarized in Table 1
<http://archinte.ama-assn.org/issues/v162n11/fig_tab/ioi10363_t1.html> . The
patients' mean age was 57.9 plusmn19.3 years (range, 18-101 years). Half
(352) of the sample were women. According to the PSI score on admission, 70%
of patients were low-risk cases (class I-III), 20% were moderate risk (class
IV), and 8%, high risk (class V). One quarter (165) of patients had 1 major
comorbid illness, and half (345) had 2 or more.
VITAL SIGNS ON DISCHARGE AND RATES OF INSTABILITY
The mean length of hospital stay was 9.2 plusmn8.9 days (median, 7 days;
IQR, 5-10 days). The mean length of stay ranged from 7.7 to 11.3 days among
the 4 sites. The mean vital sign measures on discharge were a temperature of
36.7°C plusmn0.60°C, a heart rate of 82.4/min plusmn12.39/min, a respiratory
rate of 20.8/min plusmn3.3/min, a systolic blood pressure of 121.6 mm Hg
plusmn19.0 mm Hg, and an oxygen saturation rate of 93.6% plusmn4.7%. The
incidence of unstable vital signs on discharge ranged from 1% for a systolic
blood pressure of 90 mm Hg or lower to 5.9% for an oxygen saturation rate of
90% or lower ( Table 2
<http://archinte.ama-assn.org/issues/v162n11/fig_tab/ioi10363_t2.html> ).
Mental status and ability to maintain oral intake were both abnormal in
fewer than 2% of patients.
Overall, 130 patients (19%) had 1 or more instabilities on discharge. Among
the 117 patients with 1 instability on discharge, the most common
abnormalities were oxygenation (32%), respiratory rate (16%), heart rate
(16%), temperature (15%), mental status (8%), eating status (7%), and
systolic blood pressure (4%). Twelve patients had 2 instabilities on
discharge, and 1 patient had 3 abnormalities. Among patients with more than
1 instability on discharge, no specific combination of abnormalities
dominated. There were no differences in rates of instability on discharge
among the 4 study sites (range, 18.9%-20.6%).
OUTCOMES
In the 30 days after discharge, 23 patients (3.4%) died; the median time to
death was 18 days (IQR, 8-24 days). Sixty-seven patients were readmitted
within 30 days (9.9% readmission rate); the median time of readmission was
10 days (IQR, 4-16 days). Overall, 80 patients died or were readmitted
within 30 days of discharge (major adverse events rate, 11.8%). Ten patients
died after readmission to the hospital. Patients admitted from a nursing
home accounted for 15.0% of major events. We had data on return to usual
activities for 641 patients. Overall, 223 patients (32.8%) did not return to
their usual activities within 30 days of discharge.
UNIVARIABLE ASSOCIATIONS BETWEEN INSTABILITY ON DISCHARGE AND OUTCOMES
The greater the number of instabilities on discharge, the greater the risk
of death, readmissions, major events, and failure to return to usual
activities (P<.05 for all) ( Figure 1
<http://archinte.ama-assn.org/issues/v162n11/fig_tab/ioi10363_f1.html> ).
For example, 10.5% of patients with no instabilities on discharge died or
were readmitted within 30 days compared with 13.7% of those with 1
instability and 46.2% of those with 2 or more instabilities (P = .003). When
we considered patients with any instabilities on discharge as unstable, we
found that those who left the hospital prior to reaching stability had
higher rates of death (odds ratio [OR], 2.8; 95% confidence interval [CI],
1.2-6.7; P = .02), readmission (OR, 1.6; 95% CI, 0.9-2.9; P = .09), major
events (OR, 1.8; 95% CI, 1.0-3.0; P = .04), and failure to return to usual
activities (OR, 1.7; 95% CI, 1.1-2.6; P = .009) within 30 days ( Table 3
<http://archinte.ama-assn.org/issues/v162n11/fig_tab/ioi10363_t3.html> ).
Compared with patients with no instabilities on discharge, those with 1
unstable factor had modestly increased odds of death or readmission (OR,
1.4; 95% CI, 0.8-2.5) and not returning to usual activities (OR, 1.6; 95%
CI, 1.1-2.5) ( Table 3
<http://archinte.ama-assn.org/issues/v162n11/fig_tab/ioi10363_t3.html> ). In
contrast, having 2 or more instabilities on discharge increased the risk of
major events (death or readmission) 7-fold (OR, 7.4; 95% CI, 2.4-22.8), with
a trend toward doubling the chance of not returning to usual activities (OR,
2.5; 95% CI, 0.8-8.3). We also found a similar relationship between
instabilities on discharge and risk of adverse outcomes at 7 and 14 days
when complications are most likely to be purely pneumonia related (data not
shown).
MULTIVARIABLE ASSOCIATIONS BETWEEN INSTABILITY ON DISCHARGE AND OUTCOMES
The number of instabilities on discharge remained significantly associated
with posthospital outcomes even after controlling for other important
prognostic factors and potential confounders including: the admission PSI
score and DNR status. Patients with any instabilities on discharge had
higher risk-adjusted rates of major events (OR, 1.6; 95% CI, 1.0-2.8; P<.05)
and failure to return to usual activities (OR, 1.5; 95% CI, 1.0-2.4; P =
.04) within 30 days ( Table 3
<http://archinte.ama-assn.org/issues/v162n11/fig_tab/ioi10363_t3.html> ).
Those persons with 2 or more instabilities on discharge experienced
dramatically higher risk-adjusted rates of death (OR, 14.1; 95% CI,
3.1-69.0), readmission (OR, 3.5; 95% CI, 1.0-12.4), and total major events
(OR, 5.4; 95% CI, 1.6-18.4). Forcing other potentially important clinical
variables such as the presence of chronic obstructive pulmonary disease or
use of home oxygen therapy into the multivariable model did not alter our
findings.
We also performed a series of stratified analyses to assess whether certain
subgroups might be more sensitive to the hazards related to clinical
instability. Among the 54 patients (7.9%) who were DNR, 24.1% were
discharged prior to reaching stability compared with 18.7% who were not DNR
(P = .33). Analyses that stratified by DNR status revealed that instability
on discharge was associated with higher risk of poor outcomes in all
subgroups. Similarly, instability on discharge increased the risk of major
events across the PSI risk strata.
One of our secondary hypotheses was that patients who were unstable on
discharge would be more likely to be sent to a monitored setting such as a
skilled nursing facility and be spared adverse consequences compared with
patients returning home. The greater the number of instabilities a patient
had on discharge, the more likely they were to be discharged to a skilled
nursing facility (10.5% of patients with no instabilities on discharge,
14.9% of those with 1 instability on discharge, and 41.7% of those with 2 or
more instabilities on discharge were institutionalized; P = .007). However,
instability on discharge remained a significant predictor of risk-adjusted
rates of death, readmissions, major events, and failure to return to usual
activities even after stratifying by discharge to a skilled nursing facility
(P<.05 for all). Nor were the adverse outcomes of instability on discharge
mitigated among patients sent home with visiting nurse services compared
with those who went home alone.
We found no significant relationship between hospital length of stay and
instability on discharge. For example, the median length of stay was 7 days
(IQR, 5-10 days) in those with no instabilities, 8 days (IQR, 6-11 days) for
those with 1 instability, and 6 days (IQR, 5-9 days) for patients with 2 or
more instabilities (P = .19); the median length of stay was 8 days (IQR,
6-11 days) among patients with 1 or more instabilities (P = .28). Nor were
there any associations between the natural logarithm of length of stay (or
stays shorter than 4 days) and instability on discharge.
TEST OPERATING CHARACTERISTICS OF INSTABILITY ON DISCHARGE
From a clinical perspective, individual physicians or medical groups may
want to use a specific definition of instability to help gauge
appropriateness for hospital discharge. In this respect, the instability
criteria may be considered a type of diagnostic test for future adverse
events. The sensitivity, specificity, and predictive values of the 2
definitions of instability are displayed in Table 4
<http://archinte.ama-assn.org/issues/v162n11/fig_tab/ioi10363_t4.html> .
Instability defined as any abnormalities (1) was more sensitive than the
more extreme definition of 2 or more abnormalities (27.5% vs 7.5%), but less
specific (83.1% vs 98.8%). To put the prognostic value of the instability
information in context, knowing that a patient had 2 or more instabilities
on discharge was a better predictor of the risk of death or readmission
(positive predictive value, 46.1%) than knowing that they were DNR (positive
predictive value, 35.1%) or in the highest pneumonia risk group (PSI class
V) on admission (positive predictive value, 28.6%).
The negative predictive value of the instability information was 89% for
both definitions. There were 58 patients who were discharged with no
instabilities but who went on to die or be readmitted within 30 days. These
patients had a worse initial prognosis than the overall cohort. Half of
these patients had moderate- or high-risk pneumonia on admission (50.0%),
24.1% were DNR, and 19.3% were discharged to a nursing home. They had
similar socioeconomic status as the overall group.
COMMENT
In this multicenter, prospective cohort study, nearly 1 in 5 patients with
pneumonia left the hospital with 1 or more unstable vital sign or clinical
status factor. Leaving the hospital prior to becoming stable had important
clinical consequences because the greater the number of instabilities, the
greater the risk of death or readmission and failure to return to usual
activities. Patients with any one of 7 unstable factors on discharge had a
60% increased odds of death or readmission and a 50% increased odds of not
returning to their usual activities in the 30 days after discharge, even
after adjusting for other important prognostic factors and potential
confounders. Among the small group of patients with 2 or more unstable
factors on discharge, the risk of major adverse events increased 5-fold.
We deliberately defined stability in a clinically simple manner based on
vital signs, oxygenation, ability to eat, and mental status. All of these
factors are measured in everyday practice and have been identified by
physicians as very important in deciding the readiness to switch to oral
antibiotics and appropriateness for hospital discharge. 11
<http://archinte.ama-assn.org/issues/v162n11/rfull/#r11> We have previously
shown that once a patient is stable by these criteria, the risk of serious
clinical deterioration during the index hospitalization was 1% or less, even
in the sickest subgroup of patients. 9
<http://archinte.ama-assn.org/issues/v162n11/rfull/#r9> It is now clear
that the same criteria are strongly associated with a range of important
medical outcomes following discharge. Instability on discharge remained an
important marker of posthospital adverse outcomes even after adjusting for
pneumonia severity, comorbid illness burden, DNR status, and discharge
location. The instability criteria outlined herein can help a clinician or
case manager to quickly ascertain if a given patient is safe for discharge
(in the absence of extenuating medical or social circumstances).
Which of the 2 instability criteria modeled in our study is to be
recommended? Unfortunately, we have no easy answer to this question. The
more conservative definition (1 instability) identified more patients at
risk for doing poorly (but at a higher false-positive rate) compared with
the less conservative definition (2 instabilities) in which the opposite was
true. There was no doubt that patients with 2 or more instabilities had
extremely high rates of poor outcomes and should not be discharged in the
absence of extenuating circumstances. Individual clinicians will need to
decide for themselves if just 1 instability on discharge is an absolute
reason for continued hospitalization, since the associated increased risk of
adverse events was more modest. Though we weighed all instabilities equally
to facilitate feasibility and use in real world practice, findings from
additional analyses suggest that inability to eat and hypotension, though
uncommon, were more serious single indicators of the risk of adverse events.
All of the other factors had relatively similar prognostic weights.
Our definition of stability differed from the one used in the original RAND
study of instability on discharge in several ways. 2
<http://archinte.ama-assn.org/issues/v162n11/rfull/#r2> The criteria we
used were disease specific (eg, oxygenation), had fewer elements, and were
based on vital sign cut points closer to traditional values for stability
(eg, heart rate 100/min vs 130/min). 10
<http://archinte.ama-assn.org/issues/v162n11/rfull/#r10> However, despite
the differences in methodology, time, and patient population studied,
Kosecoff and colleagues 2
<http://archinte.ama-assn.org/issues/v162n11/rfull/#r2> also reported an
association of similar magnitude between instability on discharge and
short-term mortality. As expected, the more extreme cut points (eg,
temperature >38.4°C or heart rate >130/min), which were used in the original
RAND study, have greater specificity for predicting adverse events, though
with the trade-off of lower sensitivity.
Our study had several strengths such as its multicenter, prospective nature;
clinically simple definition of stability; focus on both fatal and nonfatal
outcomes; and use of well-validated, disease-specific risk adjustment tools.
Some limitations are worth noting. Because this was an observational study,
we cannot unambiguously infer causality. We do not know what would have
happened if patients we identified as unstable on discharge had stayed in
the hospital longer instead of being sent home. However, we do know from
previous work that most patients will stabilize over time. 9
<http://archinte.ama-assn.org/issues/v162n11/rfull/#r9> There may have been
some patients who were sent home prior to attaining stability because the
physician and patient desired intentionally less aggressive care. This was
one of the reasons why we controlled for DNR status. While we observed a
trend toward patients who were DNR being more likely to be discharged
unstable, instability on discharge exposed all patients to increased risk of
poor outcomes regardless of advanced directive status.
Because we did not have data on all vital signs in the 24 hours prior to
discharge, it is possible that some of the patients we identified as
unstable may have had 1 set of stable vital signs on discharge. However, we
knew the most abnormal value of the day, such as the highest temperature,
which usually factors heavily into medical decision making. In any event,
any abnormalities in the 24 hours prior to discharge increased the risk of
adverse outcomes. Finally, our data reflect the medical practice from 1991
to 1994, when there was considerably less pressure to shorten length of
stay. We expect that rates of instability on discharge are likely to be
higher today, which would only strengthen the importance of our findings.
CONCLUSIONS
Physicians should be aware that instability in the 24 hours prior to
discharge increases the risk of poor posthospital outcomes. At a minimum,
patients with 1 instability on discharge should have close outpatient
follow-up and appropriate patient education about warning signs and symptoms
that merit urgent medical attention. Persons with 2 or more instabilities
should almost certainly remain in the hospital for continued treatment and
observation in the absence of extenuating circumstances. From a policy
standpoint, pneumonia practice guidelines and critical pathways should
include objective criteria for judging stability on discharge to ensure that
efforts to reduce length of stay do not jeopardize patient safety. Our
findings may also have implications for quality measurement and improvement
efforts. The 2 main national quality indicators for pneumonia care focus
primarily on initial management (antibiotic selection and time to first dose
of antibiotics). 20-22
<http://archinte.ama-assn.org/issues/v162n11/rfull/#r20> Our data would
support including the proportion of patients discharged prior to attaining
clinical stability as a complementary patient safety indicator with which to
compare provider or health plan performance and stimulate quality
improvement initiatives.
Author/Article Information
From the Department of Health Policy and Division of General Internal
Medicine, Mount Sinai School of Medicine, New York, NY (Drs Halm and Siu);
the Division of General Internal Medicine and Center for Research on Health
Care, University of Pittsburgh, Pittsburgh, Pa (Drs Fine and Kapoor); VA
Pittsburgh Center for Health Services Research, VA Pittsburgh Healthcare
System, Pittsburgh (Dr Fine); the General Medicine Division, Department of
Medicine, Massachusetts General Hospital and Harvard Medical School, Boston
(Dr Singer); and the Department of Medicine, University of Alberta, Edmonton
(Dr Marrie).
Corresponding author: Ethan A. Halm, MD, MPH, Department of Health Policy,
Box 1077, Mount Sinai School of Medicine, One Gustave L. Levy Place, New
York, NY 10029 (e-mail: [log in to unmask]
<mailto:[log in to unmask]> ).
Accepted for publication October 2, 2001.
This study was supported by grant HS09973 from the Agency for Healthcare
Research and Quality, Rockville, Md, and grant HS06468 from Pneumonia PORT.
Dr Halm is also currently supported as a Generalist Physician Faculty
Scholar by the Robert Wood Johnson Foundation, Princeton, NJ.
This study was originally presented in part at the 23rd Annual Meeting of
the Society of General Internal Medicine, Boston, Mass, May 4, 2000.
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