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Click here to read this article as a CME activity
a Departments of Surgery, and Community and Family Medicine, and The Dartmouth Institute for Health Policy and Clinical Practice, Dartmouth Medical School, Hanover, New Hampshire
b Dartmouth-Hitchcock Medical Center, Hanover, New Hampshire
c Catholic Medical Center, Manchester, New Hampshire
d Fletcher Allen Health Care, Burlington, Vermont
e Eastern Maine Medical Center, Bangor, Maine
f Central Maine Medical Center, Lewiston, Maine
g Maine Medical Center, Portland, Maine
h Portsmouth Regional Hospital, Portsmouth, New Hampshire
i Dartmouth Medical School, Hanover, New Hampshire
Accepted for publication December 26, 2007.
* Address correspondence to Dr Likosky, Department of Surgery, Dartmouth-Hitchcock Medical Center, Lebanon, NH 03756 (Email: donald.likosky{at}dartmouth.edu).
| Adult cardiac surgery:
The Annals of Thoracic Surgery CME Program is located online at http://cme.ctsnetjournals.org. To take the CME activity related to this article, you must have either an STS member or an individual non-member subscription to the journal.
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Abstract |
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 Top Abstract IntroductionPatients and MethodsResultsCommentReferences |
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Methods: We conducted a cohort study of 54,397 consecutive patients undergoing primary, isolated CABG surgery between July 1, 1987, and June 30, 2006. Patient records were linked to the Social Security Administration’s Death Master File.
Results: During 390,871 person-years of follow-up, there were 17,352 deaths. There were 51,149 patients younger than 80 years, 2,661 patients aged 80 to 84 years, and 587 patients aged 85 or more years who underwent isolated CABG surgery. Crude in-hospital survival was 97.2% for those less than 80 years, 98.3% for those aged 80 to 84 years, and 87.6% for those aged 85 or more years. Patients aged 80 or more years were more likely to be female (46.9%), more likely to be emergency priority (10.2%), and more likely to have associated comorbidities than younger patients. Patients aged 85 or more years were more likely to have intraoperative and postoperative morbid events. Among patients younger than 80, median survival was 14.4 years with an annual incidence of death of 4.2%. Among patients 80 to 84 years old, median survival time was 7.4 years, with an annual incidence rate of death of 10.3%. Among patients aged 85 or more years, median survival was 5.8 years, and the annual incidence of death was 13.7%.
Conclusions: Although very elderly CABG patients have more comorbidities and more acute presentation than younger patients and their in-hospital mortality rate is high, their long-term survival is surprisingly good.
Life expectancy has increased in the developed world, with the United States Census Bureau estimating that by 2050 there will be 20 million persons over the age of 85 years [1]. Utley and Leyland [2] first reported in 1991 a series of 25 octogenarians undergoing coronary artery bypass grafting (CABG) surgery. In-hospital survival was 100%, 94% at 1 year, and 88% at 5 years [2]. With this aging population, there has been and will continue to be an increasing demand for the treatment of complex coronary artery disease among this population. With the need to service this population, it is important to provide clinicians and these patients accurate and reliable information regarding short- and long-term outcomes.
Since the time of Utley’s report, with few exceptions, additional single-center studies have reported mostly on short-term outcomes for octogenarians [3, 4]. Reports have additionally identified risk factors for mortality among this subgroup of high-risk patients [5–8]. These articles have included a mixture of cardiac procedures, have been limited by their small case counts, and have included factors other than those known preoperatively.
We examined the short- and long-term survival of consecutive patients undergoing isolated CABG surgery from 1987 through 2006 in northern New England, and determined the increased risk attributed to older age.
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Patients and Methods |
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Data Collection
Data were obtained from the registries of the NNECDSG, a voluntary research consortium composed of clinicians, research scientists, and hospital administrators. The goal of the group is to foster the continuous improvement in the quality of care, safety, and effectiveness of cardiovascular interventions through the analysis of process and outcomes data and the timely feedback of this data to the clinicians involved in providing these services [9–11]. Data are collected on all CABG in the region prospectively and are periodically validated using administrative data sources. The data collected included patient demographics, comorbid conditions, cardiac history, cardiac anatomy, cardiac function, procedural indication and priority, procedural details, and outcomes. The priority of a patient’s intervention was defined as nonelective (urgent/emergent) or elective. Urgent indicated that medical factors require the patient to stay in the hospital for the procedure before discharge. Elective was defined by medical factors that indicate the need for the procedure, but allow the patient to be discharged from the hospital with readmission at a later date. Complete definitions of these variables have been previously published [12]. Institutional Review Board (IRB) approval was obtained at each participating medical center. The IRBs of seven of our eight member centers have designated the NNECDGS as a Quality Improvement Registry, and therefore patient consent was not required. Written patient consent was obtained for the one remaining center.
Patient Follow-Up
The outcome measure for this study was all-cause mortality. Mortality through June 30, 2006, was determined by a probabilistic match of the regional registry to the Social Security Administration’s Death Master File (SSA), US Department of Commerce Technology Administration. Linkage was made using a combination of first name, last name, date of birth, date last known alive, last known state of residence, and Social Security number. The sensitivity of the SSA (92.2%) is comparable to that of the National Death Index among American-born persons (87% to 98%) [13]. Schisterman and Whitcomb [13] reported a drop of nearly 10% in the sensitivity of the SSA file among foreign-born persons.
Statistical Analysis
Patients were stratified by age categories (less than 80 years, 80 to 84 years, and 85 or more years). Characteristics were summarized by percentages for categorical variables and means for continuous variables and compared using 
2 tests and t tests, respectively. Crude and adjusted survival curves were created according to the nonparametric Kaplan-Meier method and compared using a log-rank test. A Cox proportional hazard regression model was used to compare strata of age while adjusting for baseline characteristics. Hazard ratios (HR) and 95% confidence intervals (95% CI) were calculated using younger than 80 as the referent group. Hazard ratios less than 1 indicated better survival for patients aged 80 years or older; HR greater than 1 indicated better survival for patients aged less than 80 years. To account for the effect of an aging cohort over time, we tested for an interaction between patient age and year of operation. We adjusted for the following 11 characteristics: age, sex, peripheral vascular disease, diabetes mellitus, chronic obstructive pulmonary disease, congestive heart failure, renal insufficiency (creatinine > 2 mg/dL) or renal failure, cancer, left ventricular ejection fraction, history of previous myocardial infarction, and priority at intervention. Analyses were performed using Stata release 10.0 software (Stata Corp, College Station, Texas).
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Results |
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Older age was associated with most preoperative risk factors (Table 1) and postoperative outcomes (Table 2). Survival over the entire follow-up period was statistically different across age strata, favoring the younger cohort (log-rank p < 0.001), with discharge, 1-, 5-, 10-, and 15-year survival shown in Table 3. Among patients younger than 80, median survival was 14.4 years (annual incidence of death of 4.2%). Among patients 80 to 84 years old, median survival time was 7.4 years, with an annual incidence rate of death of 10.3%. Among patients aged 85 or more years, median survival was 5.8 years, and the annual incidence of death was 13.7%. No interaction existed between patient age and year of operation (p = 0.33).
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Comment |
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Our findings are in general agreement with previous studies focused on assessing outcomes among the very elderly undergoing CABG surgery. Parry and colleagues [6] in 1994 investigated mortality among a series of 306 patients aged 70 years or more undergoing coronary or valve procedures or both from January 1987 through June 1991. In this series, mortality among emergent cases was 16.7% (n = 96) versus 1.9% among patients undergoing elective surgery (n = 210). Baskett and colleagues [14] reported a series of 15,070 patients undergoing isolated CABG surgery from 1996 through 2001. The proportion of octogenarians increased over time from 4.8% in 1996 to 6.2% in 2001 (p = 0.03). Adjusted rates of death were reported among patients aged 80 years or more versus those younger than 80 years. Octogenarians had increased odds of death (odds ratio 2.64; 95% CI: 1.95 to 3.57) relative to patients younger than 80 years. Mortality among both age groups declined over time (p for linear trend < 0.001) [14]. In our series, the percentage of patients aged 80 years or more increased from 2.5% between 1987 and 1989 to 7.8% from 2005 to 2006 (p < 0.001).
Additional research has focused on survival for this cohort of patients beyond their index admission. Rosengart and associates [15] reported mortality up to 5 years after cardiac surgery among 100 patients aged 85 or more years between 1994 and 1997. Patients were followed by the National Death Index (median survival, 40 months). Probability of survival at 1 year was 68%; at 2 years, 66%; at 3 years, 58%; and at 51 months, 41%. Mortality at 30 days was higher among patients undergoing emergent versus urgent or elective surgery (18% versus 6%). Stoica and coworkers [16] reported favorable results for 12,461 consecutive patients undergoing CABG surgery relative to an age- and sex-matched population in the United Kingdom. There were 706 patients over the age of 80 years. The 5-year survival for this cohort was 82.1% (95% CI: 79.0%, 85.1%), compared with 55.9% among the matched cohort. Underlying comorbid diseases of this matched cohort were not addressed. These findings complement those reported in the current series, and suggest continued revascularization strategies on the octogenarian population are warranted and appear to result in favorable short- and long-term survival.
Johnson and colleagues [17] reported 7,726 patients undergoing CABG or valve replacement from 1993 through 2001 (73% CABG, 8% VR, 17% CABG/VR, 2% other). Among this cohort, 522 patients were aged more than 80 years. Octogenarians had an increased risk of death (8% for 80+ years versus 2% for less than 80 years). Johnson commented that chronologic age did not equate with physiologic age. Scott and coworkers [18], in a series of 1,746 patients undergoing CABG surgery from 1999 through 2001, reported resource utilization, mortality, and morbidity. Octogenarians accounted for 8.9% of the study population, and had an increased risk of 30-day mortality (9% versus 1.2%). In our current series, the median predicted risk of in-hospital death across age strata was 1.5% (less than 80 years), 4.5% (80 to 84 years), and 8.8% (85 or more years). Twenty-five percent of the octogenarians had a predicted risk of death of less than 1%, suggesting that some octogenarians might be considered "low risk" candidates. Follow-up over more than 15 years reveals a slightly different story. The median predicted risk of death over the entire follow-up period across age strata was 25.4% (less than 80 years), 44.9% (80 to 84 years), and 50.0% (85 or more years). Twenty-five percent of the octogenarians had a predicted risk of death over the follow-up period of less than 21%.
In conclusion, our findings reveal the long-term effect of CABG in northern New England from 1987 to 2006, and demonstrate a favorable survivorship for octogenarians undergoing isolated CABG surgery relative to the general population. The care of this elderly population will become progressively more important given the estimated increase in numbers of elderly in the United States [1]. The median survivorship of those 80 to 84 years was 7.4 years, and for those aged 85 or more years, it was 5.8 years. This finding suggests that revascularization should remain a suitable option for elderly patients.
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