Systolic function, readmission rates, and survival among consecutively hospitalized patients with congestive heart failure

Congestive Heart Failure

Systolic function, readmission rates, and survival among consecutively hospitalized patients with congestive heart failure Mary McGrae McDermott, MD,a Joe Feinglass, PhD, a,d Peter I. Lee, MD, a Shruti Mehta, BA, a Brian Schmitt, MB, b'e Frank Lefevre, MD, a and Mihai Gheorghiade, MD c Chicago, I1L

We sought to describe the relation between left ventricular systolic function and rates of hospital readmission and survival among consecutively hospitalized patients with congestive heart failure. Medical records were reviewed for these patients at an academic medical center between Jan. 1, 1992, and Dec. 31, 1993. Left ventricular systolic function assessments performed within ó months before discharge were used to classify left ventricular systolic function. Hospital readmission rates and survival through Dec. 31, 1994, were compared between patients with systolic dysfunction and those with preserved systolic function. Among 412 patients hospitalized with a primary diagnosis of congestive heart failure, 224 had undergone a left ventricular function assessment during the ó months before hospital discharge. In-hospital mortality and readmission rates were higher among patients without a recent assessment of left ventricular systolic function. Of patients with systolic dysfunction, 55% versus 41% of patients with preserved systolic function were either readmitted or had an emergency room visit within ó months after discharge (p = 0.06). At 27 months' follow-up, cumulative survival probabilities were 65% for patients with preserved systolic function, 65% for patients with systolic dysfunction, and 60% for patients without a left ventricular systolic function assessment (p = 0.24). Patients without a recent left ventricular systolic function assessment have significantly higher hospital readmissi0n rates than patients with a recent systolic function assessment. Among hospitalized patients, mortality rates are comparable between patients with systolic dysfunction and those with preserved systolic function. However, patients with heart failure with systolic dysfunction may have higher readmission rates. (Am Heart J 1997;134:728-36.)

Recent data show that 30% to 40% of patients with congestive heart failure (CHF) have preserved left ventricular systolic function. 1-4 Because more than 4.5 million men and women in the United Stares have CHE as many as 1.8 million may have CHF with preserved left ventricular systolic function. 5 The morbidity and mortality rates associated with CHF are extremely high. Eighty-five percent of men and 65% of women die within 6 years of CHF diagnosis, 5

From the °Division of General Internal Medicine, bDepartrnent of Medicine, and CDivisian of Cardiology, Norfhwestern University Medical School; dlnstitute for Health Services Research and Policy Studies; and eChicago Lakeside ~ZA. Medical Center. Supported in part by a grant-in-aid from the American Heart Association of Metrapolitan Chicago. Received for publication Aug. 29, ;996; accepted March 26, 199Z Reprint requests: Mary M. McDermott, ME), Northwestern University Medical School, Division of General Internal Medicine, 303 E. Ohio St., Suite 300, Chicago, IL 60611. Copyright © 1997 by Mosby-Year Book, Inc. 0002-8703/97/$5.00 + 0 4/I/82108

and as many as 45% of hospitalized patients with CHF are readmitted within 90 days of hospital discharge. 6 Prognostic information for hospitalized patients with CHF with preserved systolic function versus systolic dysfunction is important to guide physicians' therapeutic management and to aid clinical decision making for hospitalized patients with CHE Prognostic information also will help guide future research endeavors designed to improve survival and reduce hospitalization rates for patients with CHF with each type of systolic function. Whereas some studies have suggested that preserved systolic function in CHF is associated with lower mortality rates, 7-1° others have shown no survival difference between patients with preserved systolic function and those with systolic dysfunction. 1>~3 These discrepancies in prognosis for patients with CHF with preserved systolic function may result from study selection criteria. Many prior studies of prognosis have

McDermott et al.

b e e n limited to specific subsets of patients with CHF, such as patients with c o r o n a r y artery disease, 7,8,11 elderly patients, s,l» or men. 6,13 We are u n a w a r e of prior studies c o m p a r i n g survival and readmission rates b y left

nonreadmitted patients who died within 100 days and 6 months of discharge, respectively.

Medical record review

an a c a d e m i c medical center during 1992 and 1993. Survival and readmission rates w e r e c o m p a r e d b e t w e e n

Before medical record review, a data abstraction form was developed. For each admission, the presence of CHF was confirmed by using the Framingham criteria. 14 Data recorded on the abstraction form included comorbidities, serum sodium and creatinine concentrations, arterial oxygen level, admission and discharge weights, admission blood pressure and pulse, and discharge medications. Trained health care professionals abstracted medical record data under the supervision of the principai investigator.

patients with p r e s e r v e d systolic function and those with

Comorbidity definitions

systolic dysfunction. B e c a u s e a l o w ejection fraction is

History of hypertension, diabetes mellitus, coronary revascularization, myocardial infarction, pulmonary disease, stroke or transient ischemic attack, and lower extremity peripheral vascular disease were recorded if they were documented by a physician in the admitting note. A history of cancer was defined as any previously diagnosed cancer other than a basal cell or squamous cell skin cancer documented by a physician in the admission history. Chronic renal insufficiency was defined as an admission creatinine level >1.6 mg/dl, and advanced renal disease was defined as the need for long-term dialysis. Ventricular arrhythmia was recorded if the patient was taking medication for a ventricular arrhythmia. Hypothyroidism was defined as a documented history of hypothyroidism in the physician's admission history or receipt of thyroid hormone medication. A randomly selected sample of 26 heart failure charts was abstracted a second time by the principal investigator (M. M.) for a reliability analysis of the abstracted comorbidity data. The kappa coefficient for agreement on the presence of comorbidities between the principal investigator and the chart abstractors was 0.78. Coronary artery disease was defined from review of the medical record, the electrocardiogram, and results of any thallium stress test or coronary angiogram performed before discharge from the index admission. The study institution's nuclear medicine and cardiac catheterization laboratories were searched to identify any thallium stress test or coronary angiogram ever performed before discharge from the index admission. Coronary artery disease was considered present if at least one of the following was true: (1) a history of myocardial infarction, angina, or prior coronary revascularization was documented in the admission note by a physician; (2) consecuxtive pathologic Q waves were present on the electrocardiogram; (3) reversible defects wem present on a thallium stress test; or (4) >70% stenosis in one or more coronary arteries was documented on a coronary angiogram.

ventricular systolic function t y p e a m o n g consecutively hospitalized patients with CHE By using hospital administrative databases and the National Center for Health Statistics National Death Index, w e assessed survival and readmission rates a m o n g c o n s e c u t i v e l y hospitalized patients with CHF at

associated with p o o r e r survival, w e h y p o t h e s i z e d that patients with CHF and p r e s e r v e d left ventricular systolic function w o u l d h a v e bet*er survival and f e w e r readmissions c o m p a r e d with patients with left ventticular systolic dysfunction. B e c a u s e a large p r o p o r t i o n of hospitalized patients h a d n o identifiable left ventricular systolic function assessment within 6 m o n t h s before discharge, w e characterized this g r o u p of patients and c o m p a r e d their o u t c o m e s with ~ o s e of patients with recent left ventricular systolic function assessments.

Methods Cohort inception The study hospital is part of an academic medical center serving a diverse patient population in metropolitan Chicago. Computerized files from the study institution's medical record and billing departments identified all patients discharged with a principal diagnosis of CHF (diagnosis-related group (DRG), 127) between Jan. 1, 1992, and Dec. 31, 1993. Medical records were reviewed for each patient's first CHF hospitalization (index admission) between Jan. 1, 1992, and Dec. 31, 1993. The research protocol was approved by the medical center's Institutional Review Board.

Determination of hospital readmissions and survival The National Center for Health Statistics' National Death Index was searched to identify deaths and mortality rates for all patients through Dec. 31, 1994. All emergency room visits and admissions to the study institution through Dec. 31, 1994, were identified for each patient by using the hospital's computerized billing data. Admissions subsequent to the index admission were classified according to whether they were emergency room visits, 23-hour observation admissions, or full inpatient readmissions. Full inpatient readmissions were classified according to whether the principal diagnosis at discharge was CHF (DRG, 127) or a diagnosis other than CEIF (DRG other than 127). Rates of readmission within 100 days and 6 months of discharge from the index admission were calculated after excluding

American Heart Journal Volume 134, Number 4

Left ventricular function assessment For each patient, nuclear medicine, echocardiographic, and cardiac catheterization records at the study institution were

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reviewed to identify the most recent assessments of left ventricular systolic function completed within 6 months before discharge from the index admission. Ejection fractions from echocardiograms, radionuclide angiograms, and contrast ventriculograms completed at outside institutions were documented during medicai-record abstraction and included in out analyses if they were performed within 6 months before discharge from the index admission. Patients with ejection fractions <40% on radionuclide angiogram or contrast ventriculogram were categorized with left ventricular systolic dysfunction. 1 Patients with ejection fractions >50% were categorized with preserved left ventricular systolic function. 3,15 Patients with severe aortic valve disease, severe mitral valve disease, or a large pericardial effusion were excluded from the preserved systolic function group. Patients with an ejection fraction <50% and >40% were excluded from the systolic dysfunction and preserved systolic function categories. Ejection fractions from radionuclide angiograms and contrast ventriculograms were used to classify left ventricular systolic function by using the criteria described. When this information was not available, echocardiogram reports were reviewed. Because echocardiogram results at our institution do not routinely include ejection fractions, we developed specific criteria to classify systolic function from the echocardiogram report. Patients whose echocardiograms (1) reported "preserved" or «'normal" systolic function; (2) mentioned no wall-motion abnormalities; or (3) described normal chamber sizes without mention of systolic dysfunction were classified with preserved systolic function. Patients whose echocardiograms reported moderate or severe systolic dysfunction with or without a dilated leit ventricle were classified with systolic dysfunction. By using these criteria, the principal investigator and a board-certified cardiologist (M. G.) reviewed and classified each echocardiogram report. Each reviewer was blinded to patient age and sex. The systolic-function classifications from the two independent reviews were compared. When echocardiograms could not be classified by using out definitions or when the two reviews were discrepant, echocardiogram tapes were reviewed by the board-certified cardiologist.

Chest roentgenogram and electrocardiogram assessments For patients with preserved systolic function or systolic dysfunction, all dictated chest roentgenogram reports from the index admission wem reviewed for mention of pleural effusions and interstitiaI edema. Cardiomegaly was defined from the cardiothoracic ratio. The cardiothoracic ratio was measured on the admission radiograph by a study coinvestigator who was blinded to systolic-function type. Cardiomegaly was defined as a cardiothoracic ratio >0.5. Electrocardiograms performed during the index admission were retrieved and reviewed by a board-certified cardiologist who was blinded to patient age, sex, and systolic-function

type. The prevalence of left ventricular hypertrophy, leit bundle branch block, and consecutive pathologic Q waves was assessed for patients with systolic dysfunction and preserved systolic function.

Statistics Chi-square tests of association were used to compare the significance of differences in the prevalence of clinical characteristics, hospital readmission rates, and other categoric variables between patients with systolic dysfunction and preserved systolic function. Student's t tests were used to compare length of hospital stay, age, serum creatinine concentrations, sodium concentrations, and other continuous variables between patients with the two major types of systolic function. By using the log-rank test for statisticai significance, Kaplan-Meier analyses were performed to compare survival probabilities between patients with preserved systolic function and those with left ventricular systolic dysfunction. After confinning that data mer the proportional hazards assumption, Cox proportional hazards analysis was performed to identify the signfficance of left ventricular systolic function type as an independent predictor of survival, controlling for age and sex. To characterize results for hospitalized patients who had no documented assessment of left ventricular systolic function within 6 months before discharge, we repeated analyses comparing clinical characteristics and outcomes between patients with and without an assessment of left ventricular systolic fi_mction.

Results Cohort description and severity of illness Four h u n d r e d thirty-three patients w e r e discharged with a principal diagnosis of CHF during 1992 and 1993. T w e n t y - o n e (5%) patients h a d medical records that c o u l d not b e located or did not m e e r F r a m i n g h a m criteria at their i n d e x admission. The remaining 412 medical records w e m reviewed. The N e w York Heart Association heart failure classification c o u l d b e d e t e r m i n e d from medical record r e v i e w for 96% of the cohort. A m o n g these, 325 (83%) patients h a d ctass 1V heart failure, and 58 (15%) m e t class III criteria. The underlying cause of CHF was r e c o r d e d in the medical record for just 15% of the cohort. In s o m e cases m o r e than o n e origin for heart failure was reported. A m o n g these, 51% had heart failure resulting from c o r o n a r y artery disease, 11% h a d heart failure attributable to vatve disease, 13% w e r e r e p o r t e d to h a v e heart failure c a u s e d by an alcoholic cardiomyopathy, and 21% w e r e r e p o r t e d to h a v e heart failure as a result of hypertension. The m e a n creatinine and b l o o d urea nitrogen values o n admission w e r e 1.8 and 21 m g / d l , respectively. The m e a n s o d i u m level for all patients was 138 mEq/L. The

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Clinical characteristics Mean age (yr) Female Black

Hypertension Diabetes mellitus Past myocardial infarction Past CABG or coronary angioplasty Coronary artery diseaset Cigarette smoking Advanced rend disease Pulmonary disease Past stroke or TIA History of ventriculararrhythmia Chronic renal insufficiency Atrial fibrillation History of alcoholism Hypothyroidism

Cancer Lower extremity peripheral vascular disease

All patients (n = 412)

Systolic dysfunction (n = 104)

Preserved systolic function (n = 88)

p Value *

73 54% 24% 60% 36% 27% 17% 54% 48% 3% 20% 17% 3% 20% 26% 8% 11% 14% 16%

72 42% 26% 55% 38% 33% 25% 68% 50% 2% 14% 12% 4% 22% 20% 7% 16% 16% 13%

73 71% 24% 73% 33% 14% 7% 34% 43% 5% 19% 22% 3% 19% 30% 7% 9% 14% 11%

0.57 <0.0001 0.71 0.01 0.51 <0.01 <0.001 <0.001 0.35 0.30 0.27 0.06 0.87 0.80 0.13 0.98 0.14 0.60 0.66

CABG, Coronaryartery bypassgraft; TIA, transientischemicattack. *Comparisonsare belween patientswith preservedsystolicfunctionvs systolicdysfunction. tCoronary arterydiseaseis defined as one or moreof the fol[owing: historyof myocardialinfarction,angina,or coronaryrevascularization;consecutivepathologicQ waveson electrocardiograrn;or evidenceof coronaryarterydiseaseon stressthaHiumor cardiac catheterization.

mean pO 2 on admission for the 152 patients who had an arterial blood gas performed on room air was 67 m m Hg.

Characteristics of patients without a left ventricular systolic function assessment Two hundred twenty-four (54%) of 412 patients had undergone left ventricular function assessment within 6 months before discharge from their index admission. There were no significant differences in m e a n age (73 vs 73 years; p = 0.39), the proportion of w o m e n (52% vs 56%; p = 0.39), or the proportion of African Americans (24% vs 23%; p = 0.88) between patients with and without an assessment of left ventricular function, respectively. Peripheral vascular disease was more c o m m o n among patients without a recent assessment of left ventricular function (21% vs 13%; p = 0.01). There were no other differences in clinical characteristics between the two groups. Rates of angiotensin-converting enzyme (ACE) inhibitor prescriptions at discharge were 51% and 41% for patients with and without a recent left ventricular function assessment, respectively (p = 0.64). Prescription rates of ACE inhibitors combined with digoxin or diuretics were 26% a n d 33% for patients with and without a recent left ventricular function assessment, respectively (p = 0.15). Patients without a left ventricular function assessment were more likely to

American Heart Journal Volume 134, Number 4

spend one or more days in the intensive care unit (77% vs 67%; p = 0.02) and more likely to have died during their index admission (9% vs 1%; p < 0.01). Of patients without a recent left ventricular systolic function assessment, 16% versus 12% of patients with a recent left ventricular systolic function assessment had a "do not resuscitate" order o n the medical record (p = 0.24).

Characteristics associated with preserved systolic function and systolic dysfunction Of the 224 patients who had undergone a left ventricular systolic function assessment within the previous 6 months, 104 (46%) patients w e m classified with systolic dysfunction and 88 (39%) were classified with preserved systolic function. Six additional patients had preserved systolic function in conjunction with severe mitral or aortic valve disease and were excluded from the preserved systolic function category. Four patients (3%) had an ejection fraction both <50% and >40% or features of both types of systolic function on echocardiography. These patients w e m excluded from the preserved and systolic dysfunction groups. Twentytwo patients (10%) had echocardiograms that were of poor quality or could not be located for review. Table I compares clinical characteristics between patients with preserved systolic function and those with

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Characteristic

Systolic dysfunction (n = 104)

Preserved systolic function (n = 88)

p Value*

73% 100% 67%

61% 92% 46%

<0.01 0,04 0.02

38% 10% 29%

16% 0 13%

<0.01 <0.01 0.01

104 mm Hg 137 mEq/L 30 mg/dl 1.74 mg/dl 67 mm Hg

110 mm Hg 138 mEq/L 29 mg/dl 1.94 mg/dl 66 mm Hg

Radiographiccharacteristics* Pleural effusions Cardiomegaly Interstitialedema Electrocardiographic characteristics Q waves Left bundle branch block Left ventricularhypertrophy

Laboratoryand physicalexaminationcharacteristics Mean arterialpressure Sodium BUN

Creatininelevel Oxygen level t

0.40 0.16 0.67 0.42 0.87

BUN, BIood urea nitrogen. *Any radiographsperforrnedduringthe indexadmissionand their dicta¢edreportswere reviewed.Heuraleffusionsand interstit]dedemawere consideredpresentif reportedon any of the dictated radiographicreports.The cardiothoracicratio was measuredfor each admissionradiograph.Cardiomegalywas defined as a cardiothoracicraiio >0.5. tOxygen levelsare reportedfor patientswho had a room air arteriaJblaad gas perforrnedon adrnission.

systolic dysfunction. Patients with preserved systolic function were more often w o m e n and were more often hypertensive than were patients with systolic dysfunction. Patients with left ventricular systolic dysfunction were significantly more likely to have undergone coronary revascularization, more likely to have a history of coronary artery disease, and more likely to have had a prior myocardial infarction.

Drug-prescribing patterns for patients with preserved versus systolic dysfunction At discharge, ACE inhibitors were prescribed to 72% of patients with systolic dysfuncüon versus 30% of patients with preserved systolic function (p < 0.001). Prescription rates of ACE inhibitors combined with diuretics and digoxin were 53% and 13% for patients with systolic dysfunction and preserved systolic function, respectively (p < 0.001). In contrast, ]3-blockers or calcium channel blockers were more frequently prescribed to patients with preserved systolic function (52% vs 14%; p < 0.001).

Chest roentgenogram, electrocardiograrn, and physical and laboratory findings As shown in Table II, radiographic findings of pleural effusion, cardiomegaly, and interstitial edema were all more common among patients with systolic dysfunction. On the electrocardiogram, clinically signfficant electrocardiographic Q waves, left bundle branch block, and left ventricular hypertrophy were more frequently

present among patients with systolic dysfunction. There were no significant differences in mean arterial pressure, sodium, blood urea nitrogen, creatinine, or arterial oxygen levels between patients with systolic dysfunction and those with preserved systolic function.

Readmission rates and emergency room visits Among the 353 patients discharged alive, 245 (69%) patients had one or more emergency room visits or hospital readmissions over a mean follow-up period of 1.61 years. These 245 patients had 133 emergency room visits and 730 readmissions through December 31, 1994, for an average of 3.5 admissions per patient. Among 510 full (non-23-hour) inpatient stays, 137 (27%) were readmissions with a principal diagnosis of CHF (DRG, 127), and 373 (73%) were readmissions with a principal diagnosis other than CHE

Readmission rates among patients without a recent left ventricular systolic function assessment Patients without a left ventricular systolic function assessment were significantly more likely to be readmitted or to visit the emergency room within 6 months of hospital discharge than wem patients w h o had undergone a left ventricular systolic function assessment (57% vs 46%; p = 0.04). Rates of readmission or emergency room visits within 100 days of discharge were 50% and 40%, respectively (p = 0.05). There were no significant differences in the proportion of patients without and with a left ventricular systolic function

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60%

50%

40%

E

=o 30°/° 20%

10%

0%

Hundred Day Readmissions

Six Month Readmissions

Rates of lO0-day and 6-month readmissionsby systolicfunction type among hospitalized patientswith congestiveheart failure.

assessment who were readmitted for diagnoses other than CHF (45% vs 41%; p = 0.30). The frequency of emergency room visits between patients without and with a recent left ventricular systolic function assessment was 18% and 14%, respectively (p = 0.07). Out findings did not significantly change when patients with a "do not resuscitate" order were excluded.

Readmission rates for patients with preserved versus those with systolic dysfunction Fig. 1 shows 100-day and 6-month readmission rates by systolic-function type. Rates of either readmissions or emergency room visits within 6 months after discharge were 55% and 41% among patients with systolic dysfunction and those with preserved systolic function, respectively (p = 0.06). As shown in Fig. 2, there were no significant differences in the types of readmissions (emergency room, 23-hour, or inpatient) between patients with preserved versus those with systolic dysfunction. There were also no differences in the proportion of readmissions for CHF versus other diagnoses among patients with preserved function or systolic dysfunction.

Survival analyses Fig. 3 shows the Kaplan-Meier survival curves for patients with preserved systolic function, systolic dysfunction, and no recent left ventricular systolicfunction assessment. The cumulative probability of survival at 27 months' follow-up was 65% for patients with preserved systolic function, 65% for patients with systolic dysfunction, and 60% for patients without a left ventricular systolic-function assessment (p = 0.24). There were no significant differences in survival

American Heart Journal Vdume 134, Number 4

Inpatient CHF

Inpatient nonCHF

Observation

Emergency Room

Comparison of readmissiontypes among readmitted patients with congestiveheart failure with preserved systolicfunctionvs systolicdysfunction.

between patients with preserved systotic function and those with systolic dysfunction (p = 0.78). After excluding patients with a "do not resuscitate" designation, survival rates between patients with and w-ithout a recent assessment of left ventricular systolic function were 69% versus 61%, respectively, at 31 months' follow-up (p = 0.32). In separate Cox proportional hazards analyses including all 412 patients and controlling for age and sex, neither preserved systolic function, systolic dysfunction, nor absence of a left ventricular systolicfunction assessment independently predicted survival. Increasing age (relative hazard = 1.03; p < 0.01) and female sex (relative hazard = 0.50; p = 0.03) were independent predictors of survival in an analysis including patients with either systolic dysfunction, preserved systolic function, or no recent systolicfunction assessment.

Discussion Congestive heart failure with preserved systolic function is common CHF is the most c o m m o n discharge diagnosis among men and w o m e n age 65 years and older. The p h e n o m e n o n of preserved systolic function is increasingly recognized among patients with CHF, affecting 30% to 40% of all patients with CHE 1-4 Compared with systolic dysfunction, much less is known about heart failure with preserved systolic function. Understanding the epidemiologic and prognostic implications of heart failure with preserved systolic function will aid development of targeted interventions to prevent readmissions and mortality.

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Survival in consecutively hospitalized patients with congestive heart faiture according to systolic function type.

Previous studies of outcomes for patients with CHF Most previous studies of heart failure with preserved systolic function have focused on specific subsets of patients with heart failure, such as patients with coronary artery disease, the elderly, o r m e n . 7-9,11,13 Perhaps because of these selection criteria, previous comparisons of survival have shown contradictory results. 7-13 Some reports have documented more favorable survival among patients with preserved systolic function, 7,9,1° whereas others have shown no difference in survival between patients with each type of systolic function. To help circumvent selection biases, we compared outcomes among consecutively hospitalized patients with a primary diagnosis of CHF over a 2-year period. In contrast to previous studies, we included a comparison of readmission rates and types of readmissions.

Hospital readmissions and systolic function Out results show that among consecutively hospitalized patients with CHF, preserved systolic function is associated with a survival prognosis similar to that of patients with systolic dysfunction. Readmission rates within 6 months of discharge to the study institution were nearly significantly higher among patients with systolic dysfunction. Among readmitted patients, there w e m no differences in the proportion of emergency room visits, readmissions for CHE or readmissions for non-CHF problems between patients

with preserved systolic function and those with systolic dysfunction. Out survival findings are consistent with recently published data of consecutive patients visiting a CHF clinic. 16 In this study of 566 patients, the 1-year mortality rate was 16% among 121 patients with diastolic dysfunction versus 24% for 441 patients with systolic dysfunction (p = 0 . 2 5 ) . 17 The higher mortality rates we report for consecutively hospitalized patients with CHF are most likely a result of greater illness severity in our hospitalized cohort compared with outpatients with heart failure. Readmission rates and in-hospital mortality rate are high among patients without a recent systolicfunction assessment. Because approximately half of the patients had not undergone a left ventricular systolicfunction assessment in the past 6 months, we compared characteristics and outcomes between patients with and without a recent left ventricular systolic-function assessment. Although clinical characteristics were largely similar between patients with and without a recent left ventricular systolic function assessment, patients without a left ventricular systolic function assessment had higher rates of intensive care unit stays and higher in-hospital mortality rates than did patients with a recent systolic-function assessment. Among patients discharged alive, readmission rates were higher among patients without a recent systolic-function

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assessment. Although these higher rates of adverse outcomes may be a consequence of suboptimal therapy for patients without defined systolic ffmction, it is also possible that the absence of a left ventricular systolic function assessment represented a decision to withhold maximally aggressive care for patients with more acute illness. "Do not resuscitate" orders w e m somewhat more c o m m o n among patients without a recent evaluation of left ventricular systolic function. However, out findings for readmissions and total mortality rates did not significantly change w h e n w e excluded patients with a "do not resuscitate" status.

Comorbid illness common among hospitalized patients with CHF The high prevalence of comorbidities w e observed in o u t cohort is consistent with the older age of hospitalized patients with CHE The reported prevalences of hypertension, diabetes mellitus, prior myocardial infarction, peripherat vascular disease, and coronary revascularization are consistent with prevalences reported in other smdies of hospitalized patients with CHF. 6,17-19 Our reported mean creatinine, b l o o d urea nitrogen, and sodium levels on admission are also consistent with those reported in prior studies. 17-19 We are unaware of other studies reporting the prevalence of previously diagnosed cancer among consecutively hospitalized patients with CHF. Our definition of cancer included any previously diagnosed nonskin cancer documented on admission by a physician. Although the specffic type of cancer was not recorded, c o m m o n and potentially indolent cancers among the elderly, such as breast and prostate cancer, are likely contributors to the 14% prevalence of cancer in our cohort.

Comorbid illness as a cause of morbidity and mortality Although the National Death Index ensured complete mortatity data for all patients, w e do not have data on cause of death. It is conceivable that patients with systolic dysfunction may have b e e n more likely to die from complications of heart failure or coronary artery disease, whereas patients with preserved systolic dysfunction may have b e e n more likely to die as a consequence of other comorbid illness. However, our data showing a high number of readmissions for diagnoses other than CHF for both patients with systolic dysfunction and those with preserved systolic function suggest that comorbid illness is an important cause of adverse outcomes among all hospitalized patients with CHF. Future studies should focus on the development

American Heart.Journal Vo]ume 134, Number 4

of interventions to prevent mortality from any cause among all patients with CHE

Readmissions to other study institutions Our study design did not allow us to identify readmissions to other institutions. To ascertain the extent to which patients might have b e e n admitted to other institutions, w e randomly selected and attempted to contact a 10% subset of patients wh0 were alive at the end of 1994. We interviewed 19 patients, representing 8% of subjects w h o were alive at the end of 1994. Of these, 16 (84%) reported that they were never admitted to an institution other than the study hospital. Of 3 patients w h o reported subsequent admissions to other study institutions, 2 were admitted for causes other than CHE All 3 patients reported that their readmissions to outside institutions occurred >6 months after discharge from the index admission. We found that 69% of all patients discharged alive had one or more readmissions or emergency r o o m visits to the study institution and that each of these patients averaged 3.5 emergency room visits or readmissions during 1.61 years of follow-up. Although absence of data on readmissions is a limitation of our study, our data are significant in that total readmission rates and emergency room visits are likely to be higher than the rates w e reported. We have no reason to believe that systolic-function type inftuenced the likelihood that a patient w o u l d be rehospitalized at another institution.

Echocardiography and classification of left ventricular systolic function Many study patients had only an echocardiographic evaluation of their left ventricular systolic function without a concomitant ejection fraction. However, at our institution and others, echocardiograms without ejection fractions are frequently relied on to classify patients' types of systolic function and to guide medical management. Out rigorous, blinded method of left ventricular systolic-function assessment, in which w e used prespecffied criteria for each systolic function category and reviewed original echocardiographic tapes for those not clearly in a specffied category, should have enhanced accurate classification of systolic ffmction. Our data are representative of methods currently being used to define left ventricular function for patients with CHF at out institutions and others in the 1990s.

Conclusions The clinical characteristics of patients in our study show that regardless of systolic-function type, hospitalized patients with heart failnre have a variety of

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comorbid diseases and a high severity of illness. Although the pathophysiologic characteristics of CHF in systolic dysfunction versus preserved systolic flmction are distinct, our data show that morbidity and mortality are significant among both types of CHE Optimal pharmacologic therapy has been defined for CI-IF patients with systolic dysfunction, but comparable clinical trials are not available to guide therapy among patienrs with preserved systolic function. To reduce morbidity and mortality, prospective studies are needed to improve outcomes among the growing group of patients with heart failure and preserved systolic function. We thank Bruce Irwin and Richard Anderson for their help with obtaining and processing the hospital administrative files.

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American Heart Journal October 1997