- Email: [email protected]
Risk Evaluation of Cardiac Surgery in Octogenarians
Risk Evaluation of Cardiac Surgery in Octogenarians Raili Tuulikki Suojaranta-Ylinen, MD, PhD,* Anne Hellevi Kuitunen, MD, PhD,* Sinikka Irmeli Kukkonen, MD, PhD,* Antti Erland Vento, MD, PhD,† and Ulla-Stina Salminen, MD, PhD† Objective: To assess the predictive value of risk factors in the European System for Cardiac Operative Risk Evaluation (EuroSCORE) for cardiac surgery on octogenarians. Design: An observational study of octogenarians undergoing cardiac surgery and average-aged controls matched according to the cardiac surgical procedure. Setting: A university hospital. Participants: One hundred sixty-two consecutive patients 80 years or older who underwent cardiac surgery between January 1, 2001, and June 30, 2003, and 162 average-aged controls. Interventions: None. Measurements and Main Results: Risk factors according to the EuroSCORE (The European System for Cardiac Risk Evaluation) model and EuroScore algorithm without an age component (EuroSCOREex) were evaluated. The EuroSCORE model and EuroSCOREex predicted mortality (odds ratio 1.4) and morbidity (odds ratio 1.2 and 1.3, respectively)
equally well in both age groups. Adding age group information into the EuroSCOREex model in combined data, the odds ratio estimate was 3.5 for age group. The 30-day mortality of octogenarians was 8.6% versus 1.9% in controls (p < 0.01). Incidences of organ-related complications were comparable. Octogenarians spent more days in the hospital’s intensive care unit and surgical ward than did controls (3.4 ⴞ 3.3 days v 2.7 ⴞ 3.1 days, p < 0.01; 9.9 ⴞ 5.8 days v 8.6 ⴞ 3.8 days, p ⴝ 0.02). Only 31 (19.1%) octogenarians were discharged home, whereas the corresponding number was 66 (40.7%) in controls (p < 0.01). Conclusions: Risk factors other than age were not higher in octogenarians, and the EuroSCORE model predicted mortality and morbidity. Age was an important single risk factor predicting mortality. © 2006 Elsevier Inc. All rights reserved.
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5 years over 60. In its original database of 19,030 patients, the proportion of octogenarians was not reported.13 The author’s clinical hypothesis is that risk factors in octogenarians may be elevated. Thus, this study was conducted to evaluate the predictive performance of risk factors according to the EuroSCORE model for the mortality and morbidity of octogenarians compared with those of younger patients undergoing similar cardiac surgical procedures. In addition, using the EuroSCORE model without an age component, the study focused on the question of whether risk factors other than age are accentuated in the elderly. The authors’ interest was also in the mortality and morbidity of octogenarians treated with surgical techniques.
HE ELDERLY SEGMENT of the population in Finland is increasing rapidly. According to recent information from Statistics Finland, 188,432 of the population of 5 million (3.6%) were 80 years or older in 2002, and the number of octogenarians is expected to increase by 2020 to approximately 275,000 (5.2%).1 A similar transition is occurring in the United States, Canada, and in many European countries.2-4 The number of patients 80 years or older referred for cardiac surgery will increase in the future.3,5 In previous studies, the mortality of octogenarians undergoing cardiac surgery compared with that of younger patients was only moderately increased, but their morbidity was clearly higher.3,5-9 Preoperative risk factors predicting operative mortality in these studies were quite similar for both age groups and included prior coronary artery bypass graft (CABG) surgery, emergency operation, poor preoperative condition, and preoperative renal dysfunction.2,4,6 No studies based on a preoperative cardiac risk evaluation scoring system have been published for octogenarians. The European System for Cardiac Operative Risk Evaluation (EuroSCORE), constructed from a multinational cardiac database, is widely used in Europe.10 The EuroSCORE has been validated in North America, and its discriminatory power to predict 30-day mortality was significantly better than the Society of Thoracic Surgeons algorithm.11,12 With the EuroSCORE, the contribution of age is significant: 1 score per each
From the Departments of *Anesthesia and Intensive Care Medicine and †Cardiothoracic Surgery, Helsinki University Hospital, Helsinki, Finland. Address reprint requests to Raili Suojaranta-Ylinen, MD, PhD, Department of Anesthesia and Intensive Care Medicine, Helsinki University Hospital, Meilahti Hospital,Haartmaninkatu 4, FIN-00029 HUS, Helsinki, Finland. E-mail: [email protected] © 2006 Elsevier Inc. All rights reserved. 1053-0770/06/2004-0009$32.00/0 doi:10.1053/j.jvca.2005.11.016 526
KEY WORDS: cardiopulmonary bypass, elderly, prognosis, risk analysis
METHODS Data were analyzed from 162 consecutive patients 80 years of age or older who underwent cardiac surgery between January 1, 2001, and June 30, 2003, at Helsinki University Hospital. The total number of cardiac surgical patients during this observation period was 3,305. Data were collected on demographics, risk factors according to the EuroSCORE model, and surgical procedures. Risk factors included in the EuroSCORE model10 are presented in Table 1. These data were supplemented daily with postoperative information: length of stay in the intensive care unit (ICU) and surgical ward, ICU mortality, status at discharge (admitted to secondary referral hospital or sent home), 30-day mortality, postoperative complications including arrhythmias other than atrial fibrillation requiring medical or pacemaker interventions, and perioperative myocardial infarction of which criteria were 2 of the following: persistent new Q waves in an electrocardiogram, myocardial-specific creatine kinase release, or a new regional wall motion abnormality on echocardiography. Other complications included in the data were resternotomy caused by hemorrhage or ischemia, renal failure necessitating renal replacement therapy or high doses of furosemide, stroke, new epileptic symptoms or delirium, infections in the ICU, and respiratory failure requiring prolonged ventilator support. Data on 162 octogenarians (study group) were compared with data on 162 average-aged controls who underwent a similar surgical procedure (using the average age of cardiac surgical patients each year). The
Journal of Cardiothoracic and Vascular Anesthesia, Vol 20, No 4 (August), 2006: pp 526-530
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dence intervals for small proportions were calculated by the method described by Armitage and Berry.14 The association between postoperative 30-day mortality and the risk scores was evaluated via logistic regression analysis by age group and the groups combined. Performance of the risk scores was assessed by odds ratios with 95% confidence intervals and c-indexes (equivalent to the area under the receiver-operating characteristic curve). The Hosmer and Lemeshow test was used in assessment of model goodness of fit. For complications, the same methodologic approach was applied as for the 30-day mortality. The conventional level of 5% was considered statistically significant. Statistical calculations were carried out with SAS software (SAS Inc, Cary, NC).
Table 1. The EuroSCORE Scoring System Score
Patient-related factors Age per each 5 years over 60 Female gender COPD/asthma Extra-cardiac arteriopathy Renal dysfunction Previous cardiac surgery Neurologic dysfunction Active endocarditis Critical preoperative state Cardiac-related factors Unstable angina pectoris Left ventricle dysfunction Ejection fraction 30-50% ⬍30% Recent myocardial infarct Pulmonary hypertension Operation-related factors Emergency Other than isolated CABG Surgery on thoracic aorta Postinfarct septal rupture
1 1 1 2 2 3 2 3 3
RESULTS
2 1–3 1 3 2 2 2 2 3 4
control group was matched according to surgical procedure. To investigate the possible accentuation of preoperative risk factors other than age in predicting outcome after cardiac surgery in octogenarians, the EuroSCORE model without the age component (EuroSCOREex) was used for the 2 groups Mean, standard deviation, and frequency tables provided descriptive statistics of the data. Demographics, procedural characteristics, and the 2 risk scores were compared between the groups by parametric and nonparametric analyses (t test and Wilcoxon rank sum test for continuous and Cochran-Mantel-Haenszel test for categoric data). Because of small-cell frequencies, a Fisher exact test (one-sided) was applied when the incidences of mortality and complications were analyzed. Confi-
The mean age of the 162 octogenarians was 82.1 ⫾ 2.0 years (80-89), and in the control group it was 64 ⫾ 1.72 years. The majority of study group patients were female, 94 (58%) versus 45 (27.8%) for controls (p ⬍ 0.01). The EuroSCORE was 8.6 ⫾ 2.26 in the study group versus 4.0 ⫾ 2.4 in the control group (p ⬍ 0.01), and the corresponding EuroSCOREex was 3.5 ⫾ 2.3 (range 0-11) versus 2.7 ⫾ 2.3 (range 0-10, p ⬍ 0.01). The main procedures and procedural characteristics are presented in Table 2. Three patients underwent repair of the thoracic aorta, and 4 patients had mitral valve repairs. Total mortality and morbidity data are presented in Table 3. CABG mortality without additional procedures, including both offpump and on-pump methods, was 8.7% in the study group versus 0.9% in the control group. Mortality in octogenarians undergoing CABG on-pump surgery was 10.9% versus 1.5% in the control group and 5.0% versus 0% for off-pump surgery. Octogenarians spent more days in the ICU and surgical ward than did the controls (3.4 ⫾ 3.3 v 2.7 ⫾ 3.1 days, p ⬍ 0.01; 9.9 ⫾ 5.8 v 8.6 ⫾ 3.8 days, p ⫽ 0.02, respectively). In addition, 32 (19.7%) octogenarians and 25 (15.4%) younger controls came directly to surgery from the cardiac care or ICUs because of an acute cardiac event. The majority of the older patients were discharged to local hospitals (102, 63%), instead of home (31,
Table 2. Surgical Procedures and Procedural Characteristics in Octogenarians and Controls Patients ⱖ80 Years
CABG AVR CABG ⫹ AVR Others OPCAB AO time (min) ⫾ SD CPB time (min) ⫾ SD Operative Risk Acuity Emergency Urgent Elective Missing data Resternotomy IABP
Controls ⫾ 64 Years
n ⫽ 162
%
n ⫽ 162
%
104 20 31 7 40 75 ⫾ 38 114 ⫾ 44
64.2 12.3 19.1 4.3 38.5
106 20 29 7 36 77 ⫾ 33 119 ⫾ 51
65.4 12.3 17.9 4.3 40.0
18 81 42 21 13 12
11.1 50.0 25.9 13 8.0
13 43 73 33 2 4
8.0 26.5 45.1 20.4 2.0
p Value
0.44 0.53 ⬍0.01
⬍0.01 ⬍0.01
Abbreviations: CABG, coronary artery bypass grafting; AVR, aortic valve replacement; OPCAB, off-pump coronary artery bypass grafting; CPB, cardiopulmonary bypass; AO, aortic cross-clamping time, resternotomy during ICU stay caused by bleeding or ischemia; IABP, intra-aortic balloon pump.
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SUOJARANTA-YLINEN ET AL
Table 3. Mortality and Morbidity in Octogenarians and Controls Octogenarians (n ⫽ 162)
Controls (n ⫽ 162)
Number of patients (%)
Mortality OR ⫹ ICU 30 days Complications Cardiac Renal Infectious Neurologic Respiratory Total
95% CI
Number of patients (%)
95% CI
p Value
12 (7.4) 14 (8.6)
4.3-11.8 5.3-13.3
3 (1.9) 3 (1.9)
0.7-4.4 0.7-4.4
0.02 ⬍0.01
18 (11.1) 5 (3.1) 1(0.6) 10 (6.2) 2 (1.2) 31 (19.1)
7.2-16.3 1.4-6.2 0.1-2.3 3.4-10.3 0.4-3.4 13.9-25.4
11 (6.8) 3 (1.9) 3 (1.9) 8 (4.9) 4 (2.5) 21 (13.0)
3.9-11.1 0.7-4.4 0.7-4.4 2.6-8.7 1.0-5.3 8.7-18.4
0.12 0.36 0.93 0.4 0.89 ⬍0.01
Abbreviations: OR, operating room; ICU, intensive care unit.
19.1%), with the corresponding numbers in the control group being 66 (40.7%) and 74 (45.7%) (p ⬍ 0.01). EuroSCORE and EuroSCOREex predicted mortality and morbidity equally well in both groups (Table 4). According to the mortality analysis, the effect of a unit change in EuroSCORE or EuroSCOREex increased the odds of death in both age groups by a factor of 1.4. Because of the low number of deaths in the control group, the p value did not reach significance. Based on combined data (n ⫽ 324), adding age-group information (0 for controls and 1 for octogenarians) into the EuroSCORE model (Table 5, Model 1) did not improve the model (odds ratio ⫽ 1.0 for age group); but with the EuroSCOREex model (Table 5, Model 2), the odds ratio estimate for age group was 3.5, reflecting the higher mortality of octogenarians. However, the risk increase associated with Euro-
SCOREex was similar between age groups, with no evidence for interaction between EuroSCOREex and age group (odds ratio ⫽ 1.0, p ⫽ 0.86). DISCUSSION
This study suggests that in cardiac surgery, preoperative risk factors are not accentuated in the elderly. Both EuroSCORE and EuroSCOREex predicted mortality; hence, the current EuroSCORE with its accent on age is an adequate measure of risk associated with cardiac surgery in the older population. However, octogenarians have a 4-fold higher mortality, they stay longer in the ICU and in surgical wards, and are less often discharged home than are the average-aged patient population after a similar surgical procedure. In this study, age was a reliable predictive risk factor. The
Table 4. Prediction of Mortality and Morbidity in Octogenarians and Controls
Mortality Octogenarians (14/162) MODEL 1 EuroSCORE MODEL 2 EuroSCOREex Controls (n ⫽ 3/162) MODEL 1 EuroSCORE MODEL 2 EuroSCOREex Morbidity Octogenarians (31/162) MODEL 1 EuroSCORE MODEL 2 EuroSCOREex Controls (n ⫽ 21/162) MODEL 1 EuroSCORE MODEL 2 EuroSCOREex
Odds Ratio
95% CI
p Value
1.4
1.1-1.8
⬍0.01
1.4
1.1-1.8
⬍0.01
1.4
0.9-2.0
0.11
1.4
0.9-2.0
0.10
1.2
1.0-1.4
0.08
1.2
1.0-1.4
0.06
1.3
1.1-1.5
⬍0.01
1.3
1.1-1.5
⬍0.01
C-Index
0.77 0.78
0.70 0.71
0.62 0.62
0.7 0.68
NOTE. Model 1 tests EuroSCORE and model 2 tests EuroSCOREex (EuroSCORE without age component). Frequencies and total numbers are for mortality and morbidity in both groups; p ⫽ 0.38 for mortality and 0.51 for morbidity (Hosmer and Lemeshow goodness-of-fit test).
RISK EVALUATION OF CARDIAC SURGERY
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Table 5. Prediction of Mortality Based on Combined Data (n ⴝ 324) All Patients (n ⫽ 324)
Model 1 EuroSCORE Group factor EuroSCORE group Model 2 EuroSCOREex Group factor EuroSCOREex group
Odds Ratio
95% CI
p Value
1.4 1.0 1.0
0.9-2.0 0.0-33.9 0.7-1.6
0.11 0.99 0.91
1.4 3.5 1.0
0.9-2.0 0.3-44.0 0.7-1.6
0.01 0.34 0.86
C-Index
0.81
0.81
NOTE. EuroSCOREex: EuroSCORE without age component age group information added to both models; p ⫽ 0.48 for mortality (Hosmer and Lemeshow goodness-of-fit test).
other risk factors predicted mortality and morbidity equally in the elderly and average-aged patient populations. Preoperative risk factors had no additional value for the octogenarians. The explanation may be that, in cardiac surgical patients, risk factors range across the same spectrum in different age groups. Each score in the EuroSCORE system led to increased mortality, supporting the significant value of each risk factor despite age. This result is in agreement with previous findings in octogenarians in whom emergency surgery was the best predictive factor for mortality, followed by renal failure3,4; both these risk factors are included in the EuroSCORE. These data show that both EuroSCORE and EuroSCOREex predicted morbidity less well than mortality, which is also in agreement with previous findings, and the fact that EuroSCORE was originally validated to predict mortality.10,15-17 To take into account a few other postoperative complications in the data would increase the accuracy of the EuroSCORE in predicting morbidity.16,17 This study did not include atrial fibrillation as a complication because it appears some days later in the ward and data were only collected in the ICU. The intra-aortic balloon pump was considered separately because it was already inserted in many patients preoperatively. Even with these exclusions, the data support the idea that the EuroSCORE may predict risk for serious complications associated with cardiac surgery. The overall 30-day mortality of the octogenarians was significantly higher than that of the average-aged patient population.5,6,8 However, age is not likely to be the only factor involved. Almost two thirds of the octogenarians underwent emergency or urgent surgery, and more than one third underwent procedures in addition to CABG surgery. In-hospital mortality of octogenarians in 1 previous study was 33.3% in emergency CABG surgery and 11% in urgent CABG surgery.2 Combined aortic valve replacement and CABG surgery in octogenarians has been associated with increased mortality.3 The majority of the present octogenarians were also women, which is a confirmed risk factor.3,10 Thus, the octogenarian mortality was relatively low (8.6%); in-hospital mortality for those undergoing cardiac surgery has ranged from 4.1% to 13.5%.4,5,8,9 Introducing the offpump technique into CABG surgery may have an impact on mortality.18 More than one third of these elderly patients underwent off-pump surgery. Improved techniques and technologies related to cardiopulmonary bypass, myocardial pro-
tection, surgical methods, and optimal patient selection may explain the overall trend toward the decreased mortality of octogenarians after cardiac surgery.4,5,8,9 No difference in organ-related complications appeared to exist between the 2 age groups, in contrast to previous findings.5,6,8 The total incidence of operative complications was lower in these octogenarians than in earlier reports,6,8 but interpretation of complication rates after cardiac surgery is difficult because of the variety in types of reporting among studies. Because the 2 groups were matched on the basis of surgical procedures and clustering of high-risk surgical procedures in 1 group was avoided, the authors can conclude that surgical procedure-associated morbidity in both age groups seemed to be similar. The fact that older patients with very serious comorbidity are the most readily chosen to receive either medical or cardiologic interventions may also have affected the results. Postoperative ICU and surgical ward stays for the octogenarians were longer, approximately 1 day in both units. This cannot be explained by the preoperative hospital stay in octogenarians because only 7 more of them were admitted to surgery from the hospital because of an acute cardiac event. Furthermore, fewer than one fifth of the elderly patients were discharged home. Thus, it can be stated that the octogenarians consumed more medical resources, and other medical therapies might have postponed their operations. Delayed intervention in an urgent situation for an octogenarian can in part explain major complications or interventions such as resternotomy or use of intra-aortic balloon pump, both of which are known to affect length of stay.19,20 However, what has not been evaluated is whether early surgical intervention could impact on postoperative outcome in elderly people.21 The authors’ view is that surgery might still prove to be cost-effective compared with medical management in octogenarians.22 It is concluded that the EuroSCORE algorithm including age as a stepwise risk factor predicts mortality well in the oldest cardiosurgical patient group, and no single risk factor except age is accentuated in the elderly. Together with good clinical experience, the EuroSCORE algorithm provides a helpful tool for optimizing patient selection, informing patients and relatives, and estimating postoperative care resources.
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REFERENCES 1. Statistics Finland: Statistics of population and predicted population in Finland, 2003. Available at: http://www.tilastokeskus.fi 2. Williams DB, Carrillo RG, Traad EA, et al: Determinants of operative mortality in octogenarians undergoing coronary bypass. Ann Thorac Surg 60:1038-1043, 1995 3. Kirsch M, Guesnier L, LeBesnerais P, et al: Cardiac operations in octogenarians: Perioperative risk factors for death and impaired autonomy. Ann Thorac Surg 66:60-67, 1998 4. Fruitman DS, Mac Dougall CE, Boss DB: Cardiac surgery in octogenarians: Can elderly patients benefit? Quality of life after cardiac surgery. Ann Thorac Surg 68:2129-2135, 1999 5. Graver JM, Puskas JD, Weintraub WW, et al: 601 Octogenarians undergoing cardiac surgery: Outcome and comparison with younger age groups. Ann Thorac Surg 67:1104-1110, 1999 6. Alexander KP, Anstrom KJ, Muhlbaier LH, et al: Outcomes of cardiac surgery in-patients age ⱕ80 years: Results from the National Cardiovascular Network. J Am Coll Cardiol 35:731-738, 2000 7. Smith KM, Lamy A, Arthur HM, et al: Outcomes and costs of coronary artery bypass grafting: Comparison between octogenarians and septuagenarians at a tertiary care center. CMAJ 165:759-764, 2001 8. Barnett SD, Halpin LS, Speir AM, et al: Postoperative complications among octogenarians after cardiovascular surgery. Ann Thorac Surg 76:726-731, 2003 9. Avery GJ, Ley SJ, Hill JD, et al: Cardiac surgery in the octogenarian: evaluation of risk, cost and outcome. Ann Thorac Surg 71:591596, 2001 10. Nashef SAM, Roques F, Michel P, et al: European system for cardiac operative risk evaluation (EuroSCORE). Eur J Cardiothorac Surg 16:9-13, 1999 11. Nashef SAM, Roques F, Hammill BG, et al: Validation of European system for cardiac operative risk evaluation (EuroSCORE) in North American cardiac surgery. Eur J Cardiothorac Surg 22:101-105, 2002
12. Nilsson J, Algotsson L, Höglund P, et al: Early mortality in coronary bypass surgery: The EuroSCORE versus the Society of Thoracic Surgeons Risk Algorithm. Ann Thorac Surg 77:1235-1240, 2004 13. Roques F, Nashef SAM, Gauducheau ME, et al: Risk factors and outcome in European cardiac surgery: Analysis of the EuroSCORE multinational database of 19030 patients. Eur J Cardiothorac Surg 15:816-823, 1999 14. Armitage P, Berry G: Statistical Methods in Medical Research (ed 2). Oxford, UK, Blackwell, 1987, pp 117-120 15. Geissler HJ, Hölzl P, Marohl S, et al: Risk stratification in heart surgery: Comparison of six score systems. Eur J Cardiothorac Surg 17:400-406, 2000 16. Kurki TS, Järvinen O, Kataja MJ, et al: Performance of three preoperative risk indices; CABDEAL, EuroSCORE and Cleveland models in a prospective coronary bypass database. Eur J Cardiothorac Surg 21:406-410, 2002 17. Pitkänen O, Niskanen M, Rehnberg S, et al: Intra-institutional prediction of outcome after cardiac surgery: Comparison between a locally derived model and the EuroSCORE. Eur J Cardiothorac Surg 18:703-710, 2000 18. Hoff SJ, Ball SK, Coltharp WH, et al: Coronary artery bypass in patients 80 years and over: Is off-pump the operation of choice? Ann Thorac Surg 74:S1340-S1343, 2002 19. Karthik S, Grayson AD, Mc Carron EE, et al: Reexploration for bleeding after coronary artery bypass surgery: Risk factors, outcomes, and the effect of time delay. Ann Thorac Surg 78:527-534, 2004 20. Aranki SF, Shaw DP, Adams DH, et al: Predictors of arterial fibrillation after coronary artery surgery: current trends and impact on hospital resources. Circulation 94:390-397, 1996 21. Rady MY, Johnson DJ: Cardiac surgery for octogenarians: Is it an informed decision? Am Heart J 147:347-353, 2004 22. Sollano JA, Rose EA, Williams DL, et al: Cost-effectiveness of coronary artery bypass surgery in octogenarians. Ann Surg 228:297306, 1998
equally well in both age groups. Adding age group information into the EuroSCOREex model in combined data, the odds ratio estimate was 3.5 for age group. The 30-day mortality of octogenarians was 8.6% versus 1.9% in controls (p < 0.01). Incidences of organ-related complications were comparable. Octogenarians spent more days in the hospital’s intensive care unit and surgical ward than did controls (3.4 ⴞ 3.3 days v 2.7 ⴞ 3.1 days, p < 0.01; 9.9 ⴞ 5.8 days v 8.6 ⴞ 3.8 days, p ⴝ 0.02). Only 31 (19.1%) octogenarians were discharged home, whereas the corresponding number was 66 (40.7%) in controls (p < 0.01). Conclusions: Risk factors other than age were not higher in octogenarians, and the EuroSCORE model predicted mortality and morbidity. Age was an important single risk factor predicting mortality. © 2006 Elsevier Inc. All rights reserved.
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5 years over 60. In its original database of 19,030 patients, the proportion of octogenarians was not reported.13 The author’s clinical hypothesis is that risk factors in octogenarians may be elevated. Thus, this study was conducted to evaluate the predictive performance of risk factors according to the EuroSCORE model for the mortality and morbidity of octogenarians compared with those of younger patients undergoing similar cardiac surgical procedures. In addition, using the EuroSCORE model without an age component, the study focused on the question of whether risk factors other than age are accentuated in the elderly. The authors’ interest was also in the mortality and morbidity of octogenarians treated with surgical techniques.
HE ELDERLY SEGMENT of the population in Finland is increasing rapidly. According to recent information from Statistics Finland, 188,432 of the population of 5 million (3.6%) were 80 years or older in 2002, and the number of octogenarians is expected to increase by 2020 to approximately 275,000 (5.2%).1 A similar transition is occurring in the United States, Canada, and in many European countries.2-4 The number of patients 80 years or older referred for cardiac surgery will increase in the future.3,5 In previous studies, the mortality of octogenarians undergoing cardiac surgery compared with that of younger patients was only moderately increased, but their morbidity was clearly higher.3,5-9 Preoperative risk factors predicting operative mortality in these studies were quite similar for both age groups and included prior coronary artery bypass graft (CABG) surgery, emergency operation, poor preoperative condition, and preoperative renal dysfunction.2,4,6 No studies based on a preoperative cardiac risk evaluation scoring system have been published for octogenarians. The European System for Cardiac Operative Risk Evaluation (EuroSCORE), constructed from a multinational cardiac database, is widely used in Europe.10 The EuroSCORE has been validated in North America, and its discriminatory power to predict 30-day mortality was significantly better than the Society of Thoracic Surgeons algorithm.11,12 With the EuroSCORE, the contribution of age is significant: 1 score per each
From the Departments of *Anesthesia and Intensive Care Medicine and †Cardiothoracic Surgery, Helsinki University Hospital, Helsinki, Finland. Address reprint requests to Raili Suojaranta-Ylinen, MD, PhD, Department of Anesthesia and Intensive Care Medicine, Helsinki University Hospital, Meilahti Hospital,Haartmaninkatu 4, FIN-00029 HUS, Helsinki, Finland. E-mail: [email protected] © 2006 Elsevier Inc. All rights reserved. 1053-0770/06/2004-0009$32.00/0 doi:10.1053/j.jvca.2005.11.016 526
KEY WORDS: cardiopulmonary bypass, elderly, prognosis, risk analysis
METHODS Data were analyzed from 162 consecutive patients 80 years of age or older who underwent cardiac surgery between January 1, 2001, and June 30, 2003, at Helsinki University Hospital. The total number of cardiac surgical patients during this observation period was 3,305. Data were collected on demographics, risk factors according to the EuroSCORE model, and surgical procedures. Risk factors included in the EuroSCORE model10 are presented in Table 1. These data were supplemented daily with postoperative information: length of stay in the intensive care unit (ICU) and surgical ward, ICU mortality, status at discharge (admitted to secondary referral hospital or sent home), 30-day mortality, postoperative complications including arrhythmias other than atrial fibrillation requiring medical or pacemaker interventions, and perioperative myocardial infarction of which criteria were 2 of the following: persistent new Q waves in an electrocardiogram, myocardial-specific creatine kinase release, or a new regional wall motion abnormality on echocardiography. Other complications included in the data were resternotomy caused by hemorrhage or ischemia, renal failure necessitating renal replacement therapy or high doses of furosemide, stroke, new epileptic symptoms or delirium, infections in the ICU, and respiratory failure requiring prolonged ventilator support. Data on 162 octogenarians (study group) were compared with data on 162 average-aged controls who underwent a similar surgical procedure (using the average age of cardiac surgical patients each year). The
Journal of Cardiothoracic and Vascular Anesthesia, Vol 20, No 4 (August), 2006: pp 526-530
RISK EVALUATION OF CARDIAC SURGERY
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dence intervals for small proportions were calculated by the method described by Armitage and Berry.14 The association between postoperative 30-day mortality and the risk scores was evaluated via logistic regression analysis by age group and the groups combined. Performance of the risk scores was assessed by odds ratios with 95% confidence intervals and c-indexes (equivalent to the area under the receiver-operating characteristic curve). The Hosmer and Lemeshow test was used in assessment of model goodness of fit. For complications, the same methodologic approach was applied as for the 30-day mortality. The conventional level of 5% was considered statistically significant. Statistical calculations were carried out with SAS software (SAS Inc, Cary, NC).
Table 1. The EuroSCORE Scoring System Score
Patient-related factors Age per each 5 years over 60 Female gender COPD/asthma Extra-cardiac arteriopathy Renal dysfunction Previous cardiac surgery Neurologic dysfunction Active endocarditis Critical preoperative state Cardiac-related factors Unstable angina pectoris Left ventricle dysfunction Ejection fraction 30-50% ⬍30% Recent myocardial infarct Pulmonary hypertension Operation-related factors Emergency Other than isolated CABG Surgery on thoracic aorta Postinfarct septal rupture
1 1 1 2 2 3 2 3 3
RESULTS
2 1–3 1 3 2 2 2 2 3 4
control group was matched according to surgical procedure. To investigate the possible accentuation of preoperative risk factors other than age in predicting outcome after cardiac surgery in octogenarians, the EuroSCORE model without the age component (EuroSCOREex) was used for the 2 groups Mean, standard deviation, and frequency tables provided descriptive statistics of the data. Demographics, procedural characteristics, and the 2 risk scores were compared between the groups by parametric and nonparametric analyses (t test and Wilcoxon rank sum test for continuous and Cochran-Mantel-Haenszel test for categoric data). Because of small-cell frequencies, a Fisher exact test (one-sided) was applied when the incidences of mortality and complications were analyzed. Confi-
The mean age of the 162 octogenarians was 82.1 ⫾ 2.0 years (80-89), and in the control group it was 64 ⫾ 1.72 years. The majority of study group patients were female, 94 (58%) versus 45 (27.8%) for controls (p ⬍ 0.01). The EuroSCORE was 8.6 ⫾ 2.26 in the study group versus 4.0 ⫾ 2.4 in the control group (p ⬍ 0.01), and the corresponding EuroSCOREex was 3.5 ⫾ 2.3 (range 0-11) versus 2.7 ⫾ 2.3 (range 0-10, p ⬍ 0.01). The main procedures and procedural characteristics are presented in Table 2. Three patients underwent repair of the thoracic aorta, and 4 patients had mitral valve repairs. Total mortality and morbidity data are presented in Table 3. CABG mortality without additional procedures, including both offpump and on-pump methods, was 8.7% in the study group versus 0.9% in the control group. Mortality in octogenarians undergoing CABG on-pump surgery was 10.9% versus 1.5% in the control group and 5.0% versus 0% for off-pump surgery. Octogenarians spent more days in the ICU and surgical ward than did the controls (3.4 ⫾ 3.3 v 2.7 ⫾ 3.1 days, p ⬍ 0.01; 9.9 ⫾ 5.8 v 8.6 ⫾ 3.8 days, p ⫽ 0.02, respectively). In addition, 32 (19.7%) octogenarians and 25 (15.4%) younger controls came directly to surgery from the cardiac care or ICUs because of an acute cardiac event. The majority of the older patients were discharged to local hospitals (102, 63%), instead of home (31,
Table 2. Surgical Procedures and Procedural Characteristics in Octogenarians and Controls Patients ⱖ80 Years
CABG AVR CABG ⫹ AVR Others OPCAB AO time (min) ⫾ SD CPB time (min) ⫾ SD Operative Risk Acuity Emergency Urgent Elective Missing data Resternotomy IABP
Controls ⫾ 64 Years
n ⫽ 162
%
n ⫽ 162
%
104 20 31 7 40 75 ⫾ 38 114 ⫾ 44
64.2 12.3 19.1 4.3 38.5
106 20 29 7 36 77 ⫾ 33 119 ⫾ 51
65.4 12.3 17.9 4.3 40.0
18 81 42 21 13 12
11.1 50.0 25.9 13 8.0
13 43 73 33 2 4
8.0 26.5 45.1 20.4 2.0
p Value
0.44 0.53 ⬍0.01
⬍0.01 ⬍0.01
Abbreviations: CABG, coronary artery bypass grafting; AVR, aortic valve replacement; OPCAB, off-pump coronary artery bypass grafting; CPB, cardiopulmonary bypass; AO, aortic cross-clamping time, resternotomy during ICU stay caused by bleeding or ischemia; IABP, intra-aortic balloon pump.
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Table 3. Mortality and Morbidity in Octogenarians and Controls Octogenarians (n ⫽ 162)
Controls (n ⫽ 162)
Number of patients (%)
Mortality OR ⫹ ICU 30 days Complications Cardiac Renal Infectious Neurologic Respiratory Total
95% CI
Number of patients (%)
95% CI
p Value
12 (7.4) 14 (8.6)
4.3-11.8 5.3-13.3
3 (1.9) 3 (1.9)
0.7-4.4 0.7-4.4
0.02 ⬍0.01
18 (11.1) 5 (3.1) 1(0.6) 10 (6.2) 2 (1.2) 31 (19.1)
7.2-16.3 1.4-6.2 0.1-2.3 3.4-10.3 0.4-3.4 13.9-25.4
11 (6.8) 3 (1.9) 3 (1.9) 8 (4.9) 4 (2.5) 21 (13.0)
3.9-11.1 0.7-4.4 0.7-4.4 2.6-8.7 1.0-5.3 8.7-18.4
0.12 0.36 0.93 0.4 0.89 ⬍0.01
Abbreviations: OR, operating room; ICU, intensive care unit.
19.1%), with the corresponding numbers in the control group being 66 (40.7%) and 74 (45.7%) (p ⬍ 0.01). EuroSCORE and EuroSCOREex predicted mortality and morbidity equally well in both groups (Table 4). According to the mortality analysis, the effect of a unit change in EuroSCORE or EuroSCOREex increased the odds of death in both age groups by a factor of 1.4. Because of the low number of deaths in the control group, the p value did not reach significance. Based on combined data (n ⫽ 324), adding age-group information (0 for controls and 1 for octogenarians) into the EuroSCORE model (Table 5, Model 1) did not improve the model (odds ratio ⫽ 1.0 for age group); but with the EuroSCOREex model (Table 5, Model 2), the odds ratio estimate for age group was 3.5, reflecting the higher mortality of octogenarians. However, the risk increase associated with Euro-
SCOREex was similar between age groups, with no evidence for interaction between EuroSCOREex and age group (odds ratio ⫽ 1.0, p ⫽ 0.86). DISCUSSION
This study suggests that in cardiac surgery, preoperative risk factors are not accentuated in the elderly. Both EuroSCORE and EuroSCOREex predicted mortality; hence, the current EuroSCORE with its accent on age is an adequate measure of risk associated with cardiac surgery in the older population. However, octogenarians have a 4-fold higher mortality, they stay longer in the ICU and in surgical wards, and are less often discharged home than are the average-aged patient population after a similar surgical procedure. In this study, age was a reliable predictive risk factor. The
Table 4. Prediction of Mortality and Morbidity in Octogenarians and Controls
Mortality Octogenarians (14/162) MODEL 1 EuroSCORE MODEL 2 EuroSCOREex Controls (n ⫽ 3/162) MODEL 1 EuroSCORE MODEL 2 EuroSCOREex Morbidity Octogenarians (31/162) MODEL 1 EuroSCORE MODEL 2 EuroSCOREex Controls (n ⫽ 21/162) MODEL 1 EuroSCORE MODEL 2 EuroSCOREex
Odds Ratio
95% CI
p Value
1.4
1.1-1.8
⬍0.01
1.4
1.1-1.8
⬍0.01
1.4
0.9-2.0
0.11
1.4
0.9-2.0
0.10
1.2
1.0-1.4
0.08
1.2
1.0-1.4
0.06
1.3
1.1-1.5
⬍0.01
1.3
1.1-1.5
⬍0.01
C-Index
0.77 0.78
0.70 0.71
0.62 0.62
0.7 0.68
NOTE. Model 1 tests EuroSCORE and model 2 tests EuroSCOREex (EuroSCORE without age component). Frequencies and total numbers are for mortality and morbidity in both groups; p ⫽ 0.38 for mortality and 0.51 for morbidity (Hosmer and Lemeshow goodness-of-fit test).
RISK EVALUATION OF CARDIAC SURGERY
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Table 5. Prediction of Mortality Based on Combined Data (n ⴝ 324) All Patients (n ⫽ 324)
Model 1 EuroSCORE Group factor EuroSCORE group Model 2 EuroSCOREex Group factor EuroSCOREex group
Odds Ratio
95% CI
p Value
1.4 1.0 1.0
0.9-2.0 0.0-33.9 0.7-1.6
0.11 0.99 0.91
1.4 3.5 1.0
0.9-2.0 0.3-44.0 0.7-1.6
0.01 0.34 0.86
C-Index
0.81
0.81
NOTE. EuroSCOREex: EuroSCORE without age component age group information added to both models; p ⫽ 0.48 for mortality (Hosmer and Lemeshow goodness-of-fit test).
other risk factors predicted mortality and morbidity equally in the elderly and average-aged patient populations. Preoperative risk factors had no additional value for the octogenarians. The explanation may be that, in cardiac surgical patients, risk factors range across the same spectrum in different age groups. Each score in the EuroSCORE system led to increased mortality, supporting the significant value of each risk factor despite age. This result is in agreement with previous findings in octogenarians in whom emergency surgery was the best predictive factor for mortality, followed by renal failure3,4; both these risk factors are included in the EuroSCORE. These data show that both EuroSCORE and EuroSCOREex predicted morbidity less well than mortality, which is also in agreement with previous findings, and the fact that EuroSCORE was originally validated to predict mortality.10,15-17 To take into account a few other postoperative complications in the data would increase the accuracy of the EuroSCORE in predicting morbidity.16,17 This study did not include atrial fibrillation as a complication because it appears some days later in the ward and data were only collected in the ICU. The intra-aortic balloon pump was considered separately because it was already inserted in many patients preoperatively. Even with these exclusions, the data support the idea that the EuroSCORE may predict risk for serious complications associated with cardiac surgery. The overall 30-day mortality of the octogenarians was significantly higher than that of the average-aged patient population.5,6,8 However, age is not likely to be the only factor involved. Almost two thirds of the octogenarians underwent emergency or urgent surgery, and more than one third underwent procedures in addition to CABG surgery. In-hospital mortality of octogenarians in 1 previous study was 33.3% in emergency CABG surgery and 11% in urgent CABG surgery.2 Combined aortic valve replacement and CABG surgery in octogenarians has been associated with increased mortality.3 The majority of the present octogenarians were also women, which is a confirmed risk factor.3,10 Thus, the octogenarian mortality was relatively low (8.6%); in-hospital mortality for those undergoing cardiac surgery has ranged from 4.1% to 13.5%.4,5,8,9 Introducing the offpump technique into CABG surgery may have an impact on mortality.18 More than one third of these elderly patients underwent off-pump surgery. Improved techniques and technologies related to cardiopulmonary bypass, myocardial pro-
tection, surgical methods, and optimal patient selection may explain the overall trend toward the decreased mortality of octogenarians after cardiac surgery.4,5,8,9 No difference in organ-related complications appeared to exist between the 2 age groups, in contrast to previous findings.5,6,8 The total incidence of operative complications was lower in these octogenarians than in earlier reports,6,8 but interpretation of complication rates after cardiac surgery is difficult because of the variety in types of reporting among studies. Because the 2 groups were matched on the basis of surgical procedures and clustering of high-risk surgical procedures in 1 group was avoided, the authors can conclude that surgical procedure-associated morbidity in both age groups seemed to be similar. The fact that older patients with very serious comorbidity are the most readily chosen to receive either medical or cardiologic interventions may also have affected the results. Postoperative ICU and surgical ward stays for the octogenarians were longer, approximately 1 day in both units. This cannot be explained by the preoperative hospital stay in octogenarians because only 7 more of them were admitted to surgery from the hospital because of an acute cardiac event. Furthermore, fewer than one fifth of the elderly patients were discharged home. Thus, it can be stated that the octogenarians consumed more medical resources, and other medical therapies might have postponed their operations. Delayed intervention in an urgent situation for an octogenarian can in part explain major complications or interventions such as resternotomy or use of intra-aortic balloon pump, both of which are known to affect length of stay.19,20 However, what has not been evaluated is whether early surgical intervention could impact on postoperative outcome in elderly people.21 The authors’ view is that surgery might still prove to be cost-effective compared with medical management in octogenarians.22 It is concluded that the EuroSCORE algorithm including age as a stepwise risk factor predicts mortality well in the oldest cardiosurgical patient group, and no single risk factor except age is accentuated in the elderly. Together with good clinical experience, the EuroSCORE algorithm provides a helpful tool for optimizing patient selection, informing patients and relatives, and estimating postoperative care resources.
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12. Nilsson J, Algotsson L, Höglund P, et al: Early mortality in coronary bypass surgery: The EuroSCORE versus the Society of Thoracic Surgeons Risk Algorithm. Ann Thorac Surg 77:1235-1240, 2004 13. Roques F, Nashef SAM, Gauducheau ME, et al: Risk factors and outcome in European cardiac surgery: Analysis of the EuroSCORE multinational database of 19030 patients. Eur J Cardiothorac Surg 15:816-823, 1999 14. Armitage P, Berry G: Statistical Methods in Medical Research (ed 2). Oxford, UK, Blackwell, 1987, pp 117-120 15. Geissler HJ, Hölzl P, Marohl S, et al: Risk stratification in heart surgery: Comparison of six score systems. Eur J Cardiothorac Surg 17:400-406, 2000 16. Kurki TS, Järvinen O, Kataja MJ, et al: Performance of three preoperative risk indices; CABDEAL, EuroSCORE and Cleveland models in a prospective coronary bypass database. Eur J Cardiothorac Surg 21:406-410, 2002 17. Pitkänen O, Niskanen M, Rehnberg S, et al: Intra-institutional prediction of outcome after cardiac surgery: Comparison between a locally derived model and the EuroSCORE. Eur J Cardiothorac Surg 18:703-710, 2000 18. Hoff SJ, Ball SK, Coltharp WH, et al: Coronary artery bypass in patients 80 years and over: Is off-pump the operation of choice? Ann Thorac Surg 74:S1340-S1343, 2002 19. Karthik S, Grayson AD, Mc Carron EE, et al: Reexploration for bleeding after coronary artery bypass surgery: Risk factors, outcomes, and the effect of time delay. Ann Thorac Surg 78:527-534, 2004 20. Aranki SF, Shaw DP, Adams DH, et al: Predictors of arterial fibrillation after coronary artery surgery: current trends and impact on hospital resources. Circulation 94:390-397, 1996 21. Rady MY, Johnson DJ: Cardiac surgery for octogenarians: Is it an informed decision? Am Heart J 147:347-353, 2004 22. Sollano JA, Rose EA, Williams DL, et al: Cost-effectiveness of coronary artery bypass surgery in octogenarians. Ann Surg 228:297306, 1998