Cardiac Operations in Patients 90 Years of Age and Older

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The Annals of Thoracic Surgery
Volume 63, Issue 6, June 1997, Pages 1685-1690

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doi:10.1016/S0003-4975(97)00091-X | How to Cite or Link Using DOI

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Original Articles

Cardiac Operations in Patients 90 Years of Age and Older

Carlos Blanche, MD^A, , Jack M Matloff, MD^A, Timothy A Denton, MD^A, Steven S Khan, MD^A, Michele A DeRobertis, RN^A, Sharon Nessim, DrPH^A and Aurelio Chaux, MD^A

^ADepartment of Cardiothoracic Surgery, Cedars-Sinai Medical Center, Los Angeles, CaliforniaUSA

Accepted 12 December 1996. 

Available online 27 August 1998.

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Abstract

Background. Growth of the elderly population worldwide, and specifically in the United States, will continue to accelerate and will have a profound impact on the cost and delivery of health care resources in the future. A medical strategy that allows the elderly to live independently is essential to most cost-effective use of our resources. The question remains as to what will be the future of surgical therapy for this increasing population.

Methods. We retrospectively studied the cases of 30 consecutive nonagenarians (mean age, 92.3 ± 1.8 years) who underwent a cardiac operation within a 9-year period. All patients were in New York Heart Association class III or IV and underwent operation urgently or emergently.

Results. The 30-day mortality rate was 10%, and the actuarial survival rates were 81% ± 8% and 75% ± 9% at 1 year and 2 years, respectively. Seventy-eight percent of survivors were in New York Heart Association class I or II within 2 years after operation and had an improved quality of life. The cost of providing care in this age group was 24% higher than in octogenarians.

Conclusions. Advanced age in and of itself (>90 years) should not be a contraindication to an open-heart operation, although morbidity, mortality, and cost may be higher. However, selective criteria identifying risks and benefits for individual patients should be applied. The aging of our population will have a profound impact on the cost and delivery of health care resources in the future. This issue must be addressed in the current debate on the provision of expensive procedures under a realigned national health-care system.

(Ann Thorac Surg 1997;63:1685–90)

Keywords: Nonagenarians; cardiac surgery; cost-effectiveness; health care resources

Article Outline

1.

Material and Methods

1.1. Financial Data

1.2. Statistical Methods

2.

Results

3.

Comment

Acknowledgements

References

Improved longevity of the population of the United States has resulted in a marked increase in the elderly population. There were 6.9 million persons 80 years of age and older in 1990, and there will be approximately 25 million by 2050. Currently, 1 in 35 Americans is older than 80 years, and by 2050, this proportion will be 1 in 12 [[1]]. The average American who reaches 65 years of age will live into his or her ninth decade [[2]]. People 90 years of age or older will number 1,900,000 by the year 2000, a 236% increase between 1980 and the end of the century [[3]]. These demographic changes are reflected in present-day cardiac surgical practice, with an increasing number of highly symptomatic elderly patients undergoing complex cardiac operations. As these changes continue to accelerate, the demand for support and acute care services will increase and will have a profound impact on health care practice and costs in the United States.

Several studies [[4], [5], [6], [7], [8], [9], [10], [11] and [12]] have demonstrated favorable results after open-heart operation in selected septuagenarians and octogenarians, and a previous study [[13]] from our institution has addressed outcomes in nonagenarians. The purpose of this retrospective study was to analyze the outcome and cost of cardiac surgical procedures in and the ensuing quality of life of 30 consecutive nonagenarians seen at a single institution over a 9-year period. We also wanted to foresee the potential impact that this form of therapy in the very elderly may have in the future under the provisions of health care reform.

1. Material and Methods

Thirty patients 90 years of age or older underwent cardiac operations between September 1986 and December 1995. Age ranged from 90 to 96 years with a mean age of 92.3 ± 1.8 years. Sixty percent of patients (n = 18) were male. Preoperative patient characteristics are shown in Table 1. All patients were in New York Heart Association (NYHA) class III or IV.

Table 1. Preoperative Characteristics of the 30 Patients

Variable	No. of Patientsa
Risk factors
Hypertension	21 (70)
History of smoking	15 (50)
Hypercholesterolemia	9 (30)
Prior myocardial infarction	8 (27)
Peripheral vascular disease	4 (13)
Family history	4 (13)
Renal dysfunction (creatinine > 2.0 mg/mL)	3 (10)
Diabetes mellitus	1 (3)
Presenting symptoms
Angina	19 (63)
CHF	20 (67)
NYHA functional class
I	0 (0)
II	0 (0)
III	12 (40)
IV	18 (60)
LVEF
>0.50	11 (37)
≥0.30–≤0.50	18 (60)
<0.30	1 (3)
Coronary artery disease
None	5 (17)
One-vessel	4 (13)
Two-vessel	8 (27)
Three-vessel	8 (27)
Left main artery	5 (17)
Prior intervention
CABG	4 (13)
AVR	1 (3)
PTCA	4 (13)

Full-size table

AVR = aortic valve replacement; CABG = coronary artery bypass grafting; CHF = congestive heart failure; LVEF = left ventricular ejection fraction; NYHA = New York Heart Association; PTCA = percutaneous transluminal coronary angioplasty.

^a Numbers in parentheses are percentages.

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Standard cardiopulmonary bypass technique with moderate systemic hypothermia (25°C) and myocardial protection achieved with antegrade blood or cold crystalloid cardioplegia and topical cooling with ice slush was employed. In addition, from 1992, cold retrograde crystalloid cardioplegia was used routinely. Twenty-four patients (80%) underwent operation on an urgent basis, and 6 patients (20%) were operated on emergently. No patient had an elective operation. No prophylactic antiarrhythmic medications were routinely given postoperatively. Intraoperative data are shown in Table 2.

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Table 2. Intraoperative Characteristics

Variable	No. of Patientsa b
Operation	30
CABG	11 (37)
AVR	7 (23)
CABG+ AVR	10 (33)
CABG+ MVR	2 (7)
Total	30
No. of distal CABG anastomoses
1	6 (26)
2	7 (30)
3	7 (30)
4	3 (13)
Total	23
Type of bypass graft
Mammary artery	4 (17)
Saphenous vein	19 (83)
CPB time (min)c	126 ± 39
Ischemic time (min)c	91 ± 29
Surgical urgency
Urgent	24 (80)
Emergency	6 (20)
Total	30

Full-size table

AVR = aortic valve replacement; CABG = coronary artery bypass grafting; CPB = cardiopulmonary bypass; MVR = mitral valve repair.

^a Number of patients applies unless otherwise indicated.
^b Numbers in parentheses are percentages.
^c Data are shown as the mean ± the standard deviation.

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1.1. Financial Data

Financial data, including direct and indirect costs, were obtained from the hospital’s cost-accounting system. Direct costs encompass patient care–related issues such as salaries, supplies, repair and maintenance of equipment, outside training, and transfer expenses. Indirect costs include building maintenance, equipment depreciation, departmental overhead, employee benefits, support services such as communications, hospital information systems, accounting, and medical records, and other administrative costs. Total cost, as the sum of direct and indirect costs, was available for 28 of the 30 patients. Outpatient costs were not available, and professional fees were not included in this analysis.

Follow-up assessment included eval‎uation of general health compared with that before operation (improved, same, or worse) and assessment of current level of activity (NYHA class). Data for this analysis were taken from our prospective surgical database with long-term follow-up. Patients are followed up annually through personal interviews, mailed questionnaires, or telephone calls. No patients were lost to follow-up.

1.2. Statistical Methods

Data were summarized using frequencies and percentages for categoric variables and means and standard deviations for continuous variables. Length of stay data were summarized using the geometric mean. Survival probabilities were calculated with the actuarial method of estimation. Kaplan-Meier estimates were used to construct survival curves.

Early survival (30-day or to discharge) was compared between patient subgroups on the basis of baseline characteristics using the Fisher exact test. Survival curves were compared for NYHA class III versus NYHA class IV using the log-rank test. Survival was also compared for patients having coronary artery bypass grafting alone, coronary artery bypass grafting in combination with a valve procedure, and valve procedure only. Because of the small sample sizes, test power was too low for these comparisons.

2. Results

There were no intraoperative deaths. The in-hospital or 30-day surgical mortality rate was 10%; two deaths were due to cardiac-related causes (postoperative heart failure), and the cause of the other death was unknown. Postoperative complications were as follows: supraventricular arrhythmias, 21 patients (70); prolonged intubation (>48 hours), 7 (23); pneumonia, 2 (7); pleural effusion (thoracentesis), 2 (7); reoperation (bleeding or tamponade), 2 (7); and requirement of an intraaortic balloon pump, 1 patient (3). Mean postoperative length of stay was 13.5 days (range, 5 to 69 days), and mean total hospital length of stay (preoperative and postoperative) was 18.6 days (range, 6 to 79 days). During the same period, the mean postoperative length of stay for patients 60 to 70 years of age (n = 1,966) was 9.3 days with a mean total hospital length of stay of 12.3 days. By comparison, the mean postoperative length of stay for all patients less than 90 years old (n = 5,145) was 10.3 days with a mean total hospital length of stay of 13.8 days.

Actuarial 1-year and 2-year survival rates were 81% ± 8% and 75% ± 9%, respectively. Six of 15 patients having operation more than 3 years ago are still alive, and 4 of 8 patients undergoing operation 5 or more years ago are still alive. Mean follow-up was 24 months (range, 3 to 73 months). All operative survivors (27 patients) were interviewed personally or through formal and validated quality-of-life questionnaires [[14] and [15]]. Twenty-four patients (89%) thought their condition was better than preoperatively and overall were satisfied with their functional status, whereas 3 patients (11%) noted no real change. Twenty-one survivors (78%) were in NYHA class I or II within 2 years after operation (Table 3). Causes of late death were noncardiac in 8 patients, cardiac related in 2, and unknown in 1 patient. The survival curve for this group of patients indicates a median survival of approximately 3 years (Fig. 1).

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Table 3. New York Heart Association Class of 27 Operative Survivors

Preoperative Class	Postoperative Classa
	I	II	III	IV
I	0	0	0	0
II	0	0	0	0
III	8	0	2	1
IV	11	2	2	1

Full-size table

^a Postoperative mean value was calculated at 12 months (range, 3 to 26 months).

View Within Article

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Fig. 1. Survival curve using Kaplan-Meier estimates for nonagenarians undergoing cardiac operations.

View Within Article

The average total hospital cost for preoperative, intraoperative, and postoperative care was $51,496 ± $30,503 (range, $24,463 to $162,692). Cost was also analyzed according to the type of operation and subdivided by age groups during a similar period (Table 4). There is an increase in cost as a function of age by decile; the average increase is 19% between 60 and 70 years, 17% between 70 and 80 years, and 24% between 80 and 90 years (see Table 4). The ultimate cost of wellness could not be calculated, as postoperative outpatient costs were not available.

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Table 4. Total Hospital Cost in Relation to Type of Operation by Age Groups^a

Operation	Age Group (y)
	≥90 (n = 28)a	80–89.9 (n = 430)	70–79.9 (n = 1,130)	60–69.9 (n = 933)
CABG only	$48,220 ± 24,686	$39,958 ± 24,797	$33,884 ± 24,052	$24,467 ± 21,458
AVR only	$59,580 ± 21,392	$41,856 ± 21,713	$37,109 ± 24,765	$37,752 ± 21,175
CABG+ AVR	$50,682 ± 41,351	$44,306 ± 23,089	$43,656 ± 38,812	$44,098 ± 39,215
MVR+ CABG	$39,269 ± 0b	$54,228 ± 37,923	$43,887 ± 25,803	$59,181 ± 75,192
All	$51,986 ± 30,955	$41,884 ± 25,093	$35,686 ± 26,226	$30,048 ± 26,822

Full-size table

No financial data were available for 2 patients.

AVR = aortic valve replacement; CABG = coronary artery bypass grafting; MVR = mitral valve repair.

^a Data are shown as the mean ± the standard deviation.
^b Only one cost variable was present for this particular combination of operations and age.

View Within Article

3. Comment

Quality of life should be an important indicator in assessing the effectiveness of any surgical intervention, particularly in the elderly, as any intervention in the geriatric patient population should seek to improve functional independence. Late clinical improvement as judged by a return to an independent life-style is a goal of such therapy and may justify this approach in select elderly patients. Although functional outcomes are rarely the focus of conventional medical care in younger individuals, they may be critical determinants of the quality of life and the prognosis among the elderly. This issue is particularly important in current considerations of health care reform because of its implications for achieving most cost-effective outcomes. This debate is particularly relevant for the elderly because of suggested strategies to reduce the volume and complexity of their health care. The benefits of expensive medical and surgical cardiac interventions in this population can be questioned, as 15% of the population may be using 70% of the available resources [[16]]. The increasing emphasis on cost containment in health care is a concern that raises not only medical but also multiple ethical and political issues that must be discussed across the spectrum of professional, financial, and governmental organizations.

With the increasing number of elderly patients being referred for cardiac intervention, it is imperative to develop accurate tools for predicting outcomes for each procedure and to identify risk factors that may adversely affect morbidity, mortality, and late clinical status. However, it must be appreciated that in the elderly, models may not predict outcome accurately [[17]]. Such models need to be developed separately for older and younger individuals, and they should be tested for potential interaction between age and risk factors. Although the experience with nonagenarians does not yet allow clear definition of risk factors, it should be appreciated that several independent predictors of mortality after coronary artery bypass grafting in octogenarians have emerged. These predictors include depressed left ventricular function [[18]], left ventricular dysfunction in combination with diabetes mellitus [[19]], preoperative congestive heart failure [[8] and [9]], urgency of the surgical intervention [[8] and [9]], female sex [[8]], preoperative myocardial infarction [[8]], and comorbid illnesses such as chronic renal dysfunction and peripheral and cerebral vascular disease that increase hospital and long-term mortality [[8]]. In a multivariate analysis, Williams and co-workers [[12]] found that preoperative or postoperative renal dysfunction, pulmonary insufficiency, use of an intraaortic balloon pump, and sternal wound infection were independent predictors of increased hospital mortality in octogenarians undergoing coronary revascularization. In addition, in a study by Ko and colleagues [[9]], urgent operations were associated with a fivefold increase in operative mortality, whereas emergency operations carried an eightfold to elevenfold increase in surgical mortality. Our experience with septuagenarians and octogenarians undergoing cardiac surgical procedures has identified several preoperative risk factors that influence outcome. They include depressed left ventricular function, acute ischemic symptoms, functional NYHA class IV, emergency operation, and late referral and delay in surgical treatment [[4] and [5]]. These same clinical predictors may be significant for and equally applicable to nonagenarians, although the sample size in this series is too small to accurately identify such risk factors.

Consideration of surgical intervention in these nonagenarians was made on the basis of the life expectancy of each patient in terms of other disease factors. Despite their advanced age, the decision to offer surgical procedures to these patients was similar to that for younger individuals, but we kept in mind two fundamental issues; how long would the patient live, and what quality of life would he or she have? Age by itself was not the deciding factor. A medicoethical approach was taken that aimed more at functional improvement and quality of life than at lengthening the life expectancy. These selective criteria excluded patients with recent cerebrovascular accidents and those with multiple-organ failure as a result of cardiogenic shock. In addition, debilitating musculoskeletal disorders, advanced senile dementia, or other major psychosocial factors were considered contraindications if the potential benefits from the surgical intervention were thought to be minimal. The decision regarding operation in these nonagenarians was made with a clear understanding of the individual risks and benefits in an open discussion with the patient and the patient’s family, the anesthesiologist, and the referring physician.

Notwithstanding refinements in surgical technique, postoperative complications are frequent [[6] and [11]], and mortality remains higher than in younger patients [[8], [11] and [12]]. This increased morbidity and mortality has a multifactorial basis and is probably related to factors other than just the aging process [[12]]. It may be related to marginal reserve of elderly patients with poor tolerance for postoperative complications and their propensity for development of multiple-organ failure. In addition, the elderly may have more advanced heart disease and comorbid factors than younger patients, findings suggesting that perhaps because of their advanced age, their late referral for operation is a function of biased selection [[12]]. Our group [[17]] has argued that a mortality rate nearly equivalent to that of younger individuals can be obtained in the older population if operation is undertaken within 24 hours of admission. This aggressive approach could potentially reverse a pessimistic attitude regarding complex cardiac interventions in the elderly. Several reports [[4], [5], [6], [7], [8], [9], [10], [11] and [12]] have confirmed the safety and efficacy of this approach, which is reflected in the 10% operative mortality rate in this series of 30 consecutive nonagenarians. Further, the clinical case mix was that of more acute and greater severity of illness coupled with comorbidity (see Table 1). Most importantly, no elective operations were performed.

Previous studies [[8] and [11]] have shown that elderly patients have increased total hospital costs (exclusive of professional fees) for coronary artery bypass grafting procedures. This is a reflection of longer total and postoperative hospital stays because of postoperative complications and slower functional recovery. In addition, octogenarians have higher costs for hospital stay as the result of the increased intensity of medical services delivered per day. These increased costs have a median value 20% to 40% higher for octogenarians than for younger patients [[8]]. Because the elderly population is the fastest-growing segment of the United States population with a decreased number of younger people [[16]], the overall cost of complex cardiac interventions in this cohort of patients has major health-policy implications. As demographic changes of the baby boomers continue to accelerate, this issue will have a greater impact on the allocation of sophisticated health-care technology. For instance, it is estimated that by 2050, there will be 30,000 bypass operations performed in octogenarians yearly compared with 8,000 in 1990. In addition, by 2050, in-hospital costs for coronary artery bypass grafting alone in this cohort of patients will exceed $1.2 billion [[8]]. As the group of individuals 85 years of age and older is growing at a rate six times faster than the general population and as the cost of health care for older persons will probably double in the coming decade [[20] and [21]], the problem must be addressed.

Several studies [[5], [6], [7], [9], [10], [11], [12] and [13]] have demonstrated improved quality of life and functional results in the elderly after open heart procedures, although at an increased risk. This is confirmed in our series in which 24 (89%) of 27 operative survivors thought they had improvement in general health and functional status at late follow-up compared with preoperatively. In addition, 78% of survivors were in NYHA class I or II within 2 years after operation (see Table 3). Median survival is 2.6 years, with some patients living as long as 6 years (see Fig. 1).

One limitation of this retrospective study is the small number of patients involved, which precludes a multivariate analysis to identify the preoperative factors that may influence the development of postoperative complications or the specific cause of death. As a retrospective study, it lacks a control group for the eval‎uation of an alternative type of treatment during the same period. However, considering that all patients in this series were operated on urgently or emergently, a randomized, prospective study of that nature is not medically or ethically feasible. In addition, the socioeconomic impact of the duration and cost of rehabilitation and general aftercare comprises complex issues beyond the scope of this study, and they were not analyzed. Finally, the heterogeneity of surgical interventions in these 30 patients does not allow the establishment of guidelines for each type of intervention because of small sample size.

Open heart operation in patients 90 years of age and older is not common. However, physicians in the future will be pressured to eval‎uate increased numbers of nonagenarians in light of the good results obtained in septuagenarians and octogenarians undergoing cardiac interventions. This study represents a trend in the clinical practice at a single institution that most likely will continue in the future as these demographic changes continue to accelerate. These data have important implications regarding the debate about the provision of expensive medical procedures under a realigned health-care system. Should we be providing expensive, risky interventions to patients this age?

Our data address some aspects of this complex issue. It can be argued that nonagenarians clearly at a higher risk will not receive substantial benefits from cardiac surgical procedures. A surgical mortality rate of 10% is certainly high, and a median survival of 2.6 years to date is modest. Conversely, all these patients underwent operation on an urgent or emergent basis, and 90% of them survived the operation. Most did well clinically and had an improved quality of life. Further, though the median survival was only 2.6 years, the expected survival of this population cohort by actuarial estimates (mean age, 92.3 years) is 3.35 years for men and 3.98 years for women, figures indicating that postoperative survival is approaching the expected survival for this population at large [[22]].

How should the surgical management of nonagenarians be approached in this increasingly cost-conscious era? Some authors have suggested an age-based rationing of use of high technology. Although such rationing may seem economically attractive, it lacks fairness and proposes an age criterion over a medical benefit criterion. Inappropriate use of technology rather than high technology itself is a cause of increasing health-care costs [[23] and [24]]. Our approach should not be to construct artificial barriers, such as age, to care. As with most biologic phenomena, there is large variability in populations, and each may respond differently to a particular intervention. We propose that no single age-based criterion be used for making such decisions. Rather, careful consideration of individual patient demographic and clinical characteristics, risks, and potential benefits in a selective fashion should be the basis for these complex decisions. To deny a patient improved survival and quality-of-life benefit on the basis of age alone is not in the best interests of patients, our profession, our health care system, or our society.

Acknowledgements

We thank Kathleen Farrington for her secretarial assistance in the preparation of this manuscript and Marilyn Sanders from OrthoBiotech, Inc, for her technical expertise.

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References

1 Specer G. US Bureau of the Census: Projections of the population of the United Stage by age, sex and race; 1988 to 2080. Washington, DC: US Government Printing Office, 1989 (Current population reports; series P-25; no. 1018).

2 US Bureau of the Census. Statistical abstract of the United States; 1990, ed 110. Washington, DC: US Government Printing Office, 1990.

3 Projection of the population of the United States by age, sex and race; 1983 to 2080. Washington, DC: US Department of Commerce, Bureau of the Census, 1984 (Current population reports, Population Estimates and Projection; series P-25; no 952).

4 TP Tsai, JM Matloff and A Chaux et al., Combined valve and coronary artery bypass procedures in septuagenarians and octogenarians: results in 120 patients, Ann Thorac Surg 42 (1986), pp. 681–684. Abstract | PDF (716 K) | View Record in Scopus | Cited By in Scopus (25)

5 T-P Tsai, A Chaux and JM Matloff et al., Ten-year experience of cardiac surgery in patients aged 80 years and over, Ann Thorac Surg 58 (1994), pp. 445–451. View Record in Scopus | Cited By in Scopus (113)

6 ME Cane, C Chen and BM Bailey et al., CABG in octogenarians: early and late events and actuarial survival in comparison with a matched population, Ann Thorac Surg 60 (1995), pp. 1033–1037. Abstract | PDF (471 K) | View Record in Scopus | Cited By in Scopus (79)

7 MS Adkins, D Amalfitano, NA Harnum, GW Laub and LB McGrath, Efficacy of combined coronary revascularization and valve procedures in octogenarians, Chest 108 (1995), pp. 927–931. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (25)

8 ED Peterson, PA Cowper and JG Jollis et al., Outcomes of coronary artery bypass graft surgery in 24,461 patients aged 80 years or older, Circulation 92 (Suppl 2) (1995), pp. 85–91.

9 W Ko, JP Gold and R Lazzaro et al., Survival analysis of octogenarian patients with coronary artery disease managed by elective coronary artery bypass surgery versus conventional medical treatment, Circulation 86 (Suppl 2) (1992), pp. 191–197.

10 P Kumar, KJ Zehr, A Chang, DE Cameron and WA Baumgartner, Quality of life in octogenarians after open heart surgery, Chest 108 (1995), pp. 919–926. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (59)

11 NM Katz, RL Hannan, RA Hopkins and RB Wallace, Cardiac operations in patients aged 70 years and over: mortality, length of stay, and hospital charge, Ann Thorac Surg 60 (1995), pp. 96–101. Abstract | PDF (571 K) | View Record in Scopus | Cited By in Scopus (56)

12 DB Williams, RG Carrillo and EA Traad et al., Determinants of operative mortality in octogenarians undergoing coronary bypass, Ann Thorac Surg 60 (1995), pp. 1038–1043. Abstract | PDF (592 K) | View Record in Scopus | Cited By in Scopus (90)

13 TP Tsai, TA Denton and A Chaux et al., Results of coronary artery bypass grafting and/or aortic or mitral valve operation in patients ≥90 years of age, Am J Cardiol 74 (1994), pp. 960–962. Article | PDF (1606 K)

14 JH Abramson, M Ritter, J Gofin and JD Kark, A simplified index of physical health for use in epidemiological studies, J Clin Epidemiol 45 (1992), pp. 651–658. Abstract | Article | PDF (875 K) | View Record in Scopus | Cited By in Scopus (8)

15 AM Jette, AR Davies and PD Cleary et al., The functional status questionnaire: reliability and validity when used in primary care, J Gen Intern Med 1 (1986), pp. 143–149. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (257)

16 JM Matloff, The practice of medicine in the year 2010, Ann Thorac Surg 55 (1993), pp. 1311–1325. Abstract | PDF (2205 K) | View Record in Scopus | Cited By in Scopus (11)

17 SS Khan, JM Kupfer, JM Matloff, TP Tsai and S Nessim, Interaction of age and preoperative risk factors in predicting operative mortality for coronary bypass surgery, Circulation 86 (Suppl 2) (1992), pp. 186–190.

18 CJ Mullany, GE Darling and JR Pluth et al., Early and late results after isolated coronary artery bypass surgery in 159 patients aged 80 years and older, Circulation 82 (Suppl 4) (1990), pp. 229–236.

19 WS Weintraub, SD Clements and J Ware et al., Coronary artery surgery in octogenarians, Am J Cardiol 68 (1991), pp. 1530–1534. Abstract | PDF (531 K) | View Record in Scopus | Cited By in Scopus (31)

20 HP Dustan, MP Hamilton, C McCullough and LB Page, Sociopolitical and ethical considerations in the treatment of cardiovascular disease in the elderly, J Am Coll Cardiol 10 (1987), pp. 4A–7A.

21 WB Stason, CA Sanders and HC Smith, Cardiovascular care of the elderly: economic considerations, J Am Coll Cardiol 10 (1987), pp. 18A–21A. Abstract | PDF (411 K)

22 Population projection of the United States. Washington, DC: Bureau of the Census, Population Division, 1996.

23 L Chelluri, A Grenvik and J Silverman, Intensive care for critically ill elderly; mortality, costs and quality of life, Arch Intern Med 155 (1995), pp. 1013–1022. View Record in Scopus | Cited By in Scopus (126)

24 D Callahan, Old age and new policy, JAMA 261 (1989), pp. 905–906. View Record in Scopus | Cited By in Scopus (20)