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Asian Cardiovasc Thorac Ann 2004;12:218-223
© 2004 Asia Publishing EXchange Ltd

ORIGINAL CONTRIBUTION

Coronary Bypass Surgery in Patients Aged 70 Years and Over: Mortality, Morbidity, Length of Stay and Hospital Cost

Chye-Yew Ng, MBChB, Mohd Faizal Ramli, MSc1, Yahya Awang, FRCS1

General Surgery, Royal Infirmary of Edinburgh, Scotland
1 National Heart Institute, Kuala Lumpur, Malaysia

For reprint information contact: Chye Yew Ng, MBChB Tel: 44 131 662 9075 Fax: 44 776 674 4600 Email: cyng{at}excite.com 49 (2F1) Montague Street, Edinburgh EH8 9QS, Scotland, United Kingdom.


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 PATIENTS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
The objective of this investigation was to compare the outcome of isolated coronary artery bypass grafting surgery in patients ≥ 70 years with those < 70. The cardiac surgery database of the Institute was used to obtain the characteristics of patients undergoing coronary artery bypass grafting between January 2000 and September 2001. The patients were divided into those ≥ 70 years of age and those < 70 years old. A Parsonnet risk score was determined for each patient for the analysis of mortality, length of stay and hospital charges. During the study period, 1594 cases of isolated coronary artery bypass grafting were carried out. 184 (11.5%) cases were performed in the older group. The 30-day mortality for patients aged 70 and over was 7 (3.3%) out of 184 while that of patients < 70 years of age was 47 (3.8%) out of 1410 (p < 0.740). The overall hospital mortality was 10 (5.4%) of 184 and 53 (3.8%) of 1410 (p < 0.272) respectively. Apart from a higher incidence of wound infection in elderly patients, the frequency of other major complications was comparable in both groups. The average length of postoperative stay for the elderly patients was 10.4 ± 0.9 days compared to 8.7 ± 0.2 days for the younger group (p < 0.049). The mean hospital charge in patients ≥ 70 was RM 25,160.38 ± 1656.75 whereas for patients < 70, it was RM 21,801.47 ± 308.91 (p < 0.048). This study supports the continued performance of coronary artery bypass grafting in patients ≥ 70 years. Advanced age alone should not deter a cardiac surgeon from offering such a potentially beneficial intervention.


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
PATIENTS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
As elderly populations grow larger, cardiac surgeons are increasingly faced with the challenges of intervention in the elderly with coronary artery diseases. Elderly patients face higher surgical risks and are associated with increased mortality and morbidity rates as well as greater length of hospital stays.1,2 However, various retrospective studies have shown that cardiac surgery performed in selected elderly patients are associated with favourable outcomes.3–5 Thus far, there has not been any study on this subject in Malaysia. This would allow cardiac surgeons to reflect on their past experiences and to compare themselves to their contemporaries in other countries. The objective of this retrospective study was to compare the outcome of patients aged 70 years and above who underwent isolated coronary artery bypass grafting (CABG) surgery in the National Heart Institute (NHI), Malaysia with those younger than 70 years old.


   PATIENTS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 PATIENTS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
The cardiac surgery database of the NHI was used to obtain the characteristics of patients undergoing CABG between January 2000 and September 2001. The patients were divided into two groups, namely those who were 70 years old and above, and those less than 70. The Parsonnet risk stratification6 was integrated into our database software. In order to reduce subjectivity on the higher risk patients, we adopted the Bridgewater et al7 method which assigned an additional score of 10 points for a catastrophic state, rather than allowing a score between 10 and 50 as suggested in the original Parsonnet system. A Parsonnet risk score was determined for each patient for the analysis of mortality, length of stay and hospital charges. Both the 30-day and hospital mortalities were determined for the two groups of patients. The predicted mortality for each risk group was calculated by averaging the individual scores within each category.

Length of stay (LOS) was defined as the time from operation to hospital discharge. Prolonged length of stay was defined using a cut-off point as suggested by Tu and colleagues.8 The number of days equivalent to the 90th centile of the cumulative length of stay for the entire series was taken as the cut-off point. It was chosen because it is most likely to reflect prolonged LOS secondary to the development of morbidity.8

The information system of the hospital finance division was used to calculate the hospital charges for each patient. The total cost of the hospital stay included charges for the operating theatre, intensive care unit (ICU), ward, cardiology, laboratory, radiology, physiotherapy, pharmacy, dietetics, supplies and miscellaneous. A hospital charge ratio between the study groups was also determined by dividing the mean charges for the elderly patients by that for the younger patients.

Standard techniques of cardiopulmonary bypass were employed with moderate hypothermia to a core temperature of 28°C. Myocardial protection was achieved by cold crystalloid or cold blood cardioplegia supplemented with topical cooling with ice slush. The cardioplegia solution was given antegradely, retrogradely, or both depending on the surgeon’s preference. Eighty six (5.4%) cases of CABG were performed on beating hearts.

Results are expressed as the mean ± standard error of the mean. The {chi}2 test or Fisher’s exact test were used to compare sample proportions. The Mann-Whitney’s U test was employed to compare mean lengths of stay and the student’s t test was used to compare mean hospital charges. A p-value < 0.05 was considered statistically significant.


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 PATIENTS AND METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
During the period of the study a total of 1594 cases of isolated CABG, including 32 (2.0%) reoperations, were carried out in the Institute. Of them, 184 (11.5%) were performed in patients aged 70 and over. The baseline characteristics of the two study groups are compared in Table 1Go. There were no significant differences regarding gender, the incidence of obesity, diabetes mellitus, hypertension, left ventricular ejection fraction, renal failure, the usage of preoperative intraaortic balloon pump (IABP), or the frequency of emergency surgery. The incidence of reoperation and of significant left main stenosis (LMS) was higher in the older group. None of the elderly patients were dependent on dialysis.


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  		Table 1. Baseline Characteristics
 
The youngest patient in the study was 31 years old whilst the oldest was 83. The mean age of the younger group was 56.4 ± 0.2 years old whilst that of the older group was 72.9 ± 0.2 years old. The mean age of the whole series was 58.3 ± 0.2 years old. The age distribution of the older patients is shown in Table 2Go. Seven hundred and seventy-eight (48.8%) patients were Malay, 405 (25.4%) were Chinese, 312 (19.6%) were Indian and 99 (6.2%) were other races. At the time of CABG, coronary endarterectomy was performed in 12 (6.5%) patients aged 70 and over; and in 70 (5.0%) patients less than 70 years old (p < 0.368). Two (1.1%) patients of 70 years and over had carotid endarterectomy, compared to 3 (0.2%) in the younger group (p < 0.105). Left internal mammary artery (LIMA) was used as an arterial conduit for revascularization in 60 (32.6%) elderly patients. In contrast, it was employed as a conduit in 1065 (75.5%) younger patients (p < 0.0001). Right IMA (RIMA) was used in 1 (0.5%) patient aged over 70, and 19 (1.3%) patients less than 70 years old (p < 0.357). Fourteen (1.0%) patients less than 70 years old had bilateral IMAs as conduits for revascularization compared with none in the older group (p < 0.175).


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  		Table 2. Age Distribution of Elderly Patients
 
With regard to 30-day mortality, 7 (3.8%) out of 184 patients aged ≥ 70 died within 30 days of operation compared with 47 (3.3%) out of 1410 patients aged < 70 (p < 0.740). The overall 30-day mortality was 54 (3.4%) out of 1594. Table 3Go shows the 30-day mortalities observed for each category of the Parsonnet risk stratification for the two age groups. All elderly patients in the fair risk group survived the 30-day postoperative period. The Parsonnet model of risk stratification overestimates the mortality in each risk group. The ratio of observed-to-predicted 30-day mortality for the entire series was 0.57; for the elderly group it was 0.29 and for the younger group it was 0.66.


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  		Table 3. 30-day Mortality with Risk Stratification
 
Nine patients, who survived the initial 30-day postoperative period, died in hospital (6 of whom were younger than 70 years old). The hospital mortality then for patients ≥ 70 was 10 (5.4%) out of 184. In contrast, the hospital mortality for patients < 70 was 53 (3.8%) out of 1410. However, the difference between the mortality rates was not statistically significant (p < 0.272). The overall hospital mortality was 63 (4.0%) out of 1594. The hospital mortalities according to the risk stratification for all patients are shown in Table 4Go. The overall hospital mortality for the entire series increased according to the Parsonnet model of risk stratification.


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  		Table 4. Hospital Mortality with Risk Stratification
 
The occurrence of major complications in the two study groups is compared in Table 5Go. Apart from a higher incidence of wound infection in patients ≥ 70, the frequency of other major complications was comparable in both age groups.


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  		Table 5. Major Complications
 
The average length of postoperative stay for the elderly patients was 10.4 ± 0.9 days compared to 8.7 ± 0.2 days for the younger group (p < 0.049). Table 6Go shows the LOS for all patients according to the risk stratification. Figure 1Go shows the cumulative percentage of the LOS for the entire series. 90% of patients stayed in hospital for less than 13 days. Nineteen (10.3%) patients ≥ 70 had prolonged LOS after their operation compared to 126 (8.9%) younger patients (p < 0.537).


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  		Table 6. Length of Postoperative Stay with Risk Stratification
 


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  		Figure 1. Cumulative percentage of the length of postoperative stay.

 
The median LOS in the ICU for both age groups was one day. The mean ICU stay for the elderly group was 2.5 ± 0.3 days, and 2.3 ± 0.1 days for the younger group (p < 0.823). Seventy (38.0%) elderly patients stayed in the ICU for longer than 24 hours compared to 534 (37.9%) younger patients.

Table 7Go shows the mean hospital charges according to risk stratification. In patients ≥ 70, this was RM 25,160.38 ± 1656.75 and for patients < 70 years old, it was RM 21,801.47 ± 308.91 (p < 0.048). Thus elderly patients had 1.15 times greater charge than the younger patients.


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  		Table 7. Hospital Charges According to Risk Stratification
 

   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 PATIENTS AND METHODS
 RESULTS
 DISCUSSION
REFERENCES
 
CABG was first performed in Malaysia in 1982. However, an audit of the results of this cardiac surgery, in particular regarding the impact of age on outcome, has not been done before in this country. This study was thus carried out to shed light on some of these questions to which many of the country’s cardiac surgeons are eager to know the answers. The study represents a complete series of isolated CABG performed in a regional heart institution over a 21-month period. We appreciate that the selection of age 70 as the cut-off point to define elderly is somewhat arbitrary. However, this is in keeping with the Parsonnet model of risk stratification as additional weight for age is only given when a patient is 70 years old or older.

The use of IMA as an arterial conduit has become routine in most CABG. In a retrospective study by Katz and Chase, 186 (89%) of their 209 patients who underwent isolated CABG received at least one IMA.9 Overall, 1131 (71%) patients in our study received at least one IMA. However, the artery appeared to have been used less frequently in the elderly patients.10,11 In the present study population, LIMA was used in three quarters of the younger patients compared to only a third of the elderly group. Favourable results from IMA grafting in elderly patients have been reported.12,13 The frequency of non-use of IMA in our elderly population warrants further study.

There was no difference in either the 30-day mortality or hospital mortality between the two age groups. This is in spite of more severe coronary artery disease as indicated by the higher frequencies of reoperation and significant LMS in the older age group. In addition, the occurrence of major complications was generally low and not significantly different between the age groups. These encouraging results may be a refl ection of improved surgical technique, better myocardial protection, refinements in intensive care and reasonable patient selection.

However, the incidence of wound infection was significantly higher in the elderly patients (4.9% versus 1.8%) (p < 0.006). This could be due to age-related poorer wound healing. Of note, 22 (64.7%) out of the 34 patients who had wound infections were also diabetic (5 of whom were in the elderly group). In order to reduce the incidence of wound infection, strict aseptic technique and strict glycaemic control should be observed during the perioperative period.

The overall hospital mortality, but not the 30-day mortality, for the entire series increased with the Parsonnet risk groups. Nevertheless, this risk stratification overestimated the mortality in each risk group, which has been borne out in other studies.14,15 When the observed-to-expected mortality ratio was compared between the age groups, the elderly group had a much lower ratio than the younger group. This is in part due to a lower mortality rate in the elderly group. On the other hand, the impact of preoperative risk factors on the elderly may be more significant compared to the impact on younger patients.16 Given the rising number of elderly patients being referred for cardiac surgery, it is crucial to develop accurate models for predicting the outcome for each procedure and to identify risk factors that may adversely affect mortality, morbidity and long-term performance status.

Advanced age is a well-known predictor of increased length of hospitalization after cardiac surgery.17–19 In our institution, mean length of postoperative stay was longer by about two days in patients ≥ 70 years compared to those younger (10.4 days versus 8.7 days) (p < 0.049). This is reflected in the 15% higher overall hospital charges in the elderly patients compared to the younger patients. The longer stay may be attributable to slower functional recovery and higher intensity of medical care required for the elderly patients. However it is encouraging to note that the median postoperative length of stay for both age groups was only 7 days.

Even though the Parsonnet model was first developed to predict operative mortality of open-heart surgical patients, the risk score was also found to closely correlate with the overall complication rate and duration of postoperative hospitalization.6 Our study has confirmed its potential as a predictor of LOS as well as total hospital charges. Postoperative ICU stay longer than 24 hours indicates the presence of complications. Over 60% of patients in this study stayed in the ICU for less than 24 hours. ICU stay is a significant determinant of total hospital charges and the availability of ICU beds is often the determining factor in the turnover of surgical patients in the institution. Accordingly efficient management of ICU would have a positive impact on overall resource utilization.

Based on the findings from our study, the following conclusions can be drawn. The operative mortality for isolated CABG in patients ≥ 70 years did not differ significantly from those < 70 years old. The frequency of major complications was similar in both age groups, apart from a higher incidence of wound infection in the elderly population. Mean length of postoperative stay in elderly patients was about two days longer than that for younger patients. The mean duration of hospitalization increased with the Parsonnet risk groups. The hospital charges in patients ≥ 70 years were 15% higher than those in the younger patients. The average hospital charges correlated with the Parsonnet risk categories. Parsonnet risk stratification may be employed more widely in the prediction of LOS and hospital charges for patients undergoing CABG. Such application would have implications on the management of hospital resources and could be a useful tool in the dialogue between doctors and patients when the risks and benefits of CABG are being discussed.

Our study supports the continued performance of CABG in patients ≥ 70 years. Advanced age alone should not deter a cardiac surgeon from offering the potentially beneficial intervention of CABG.


   ACKNOWLEDGMENTS
 
This work was supported by the Royal College of Surgeons of England (Preiskel Elective Prize in Surgery), the Royal College of Physicians of Edinburgh (Myre Sim Student Bursary) and the British Medical and Dental Students’ Trust. We are grateful to Dr. Jill Tan for proof reading the manuscript.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 PATIENTS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 

  1. Edmunds LH Jr, Stephenson LW, Edie RN, Ratcliffe MB. Open-heart surgery in octogenarians. N Eng J Med 1988;319:131–6.[Abstract]

  2. Katz NM, Hannan RL, Hopkins RA, Wallace RB. Cardiac operations in patients aged 70 years and over: mortality, length of stay, and hospital charge. Ann Thorac Surg 1995;60:96–101.[Abstract/Free Full Text]

  3. Miller DJ, Samuels LE, Kaufman MS, Morris RJ, Thomas MP, Brockman SK. Coronary artery bypass surgery in nonagenarians. Angiology 1999;50:613–7.

  4. Kirsch M, Guesnier L, LeBesnerais P, Hillion ML, Bebauchez M, Seguin J, et al. Cardiac operations in octogenarians: perioperative risk factors for death and impaired autonomy. Ann Thorac Surg 1998;66:60–7.[Abstract/Free Full Text]

  5. Peterson ED, Cowper PA, Jollis JG, Debchuk JD, DeLong ER, Muhlbaier LH, et al. Outcomes of coronary artery bypass graft surgery in 24,461 patients aged 80 years or older. Circulation 1995;92:85–91.[Abstract/Free Full Text]

  6. Parsonnet V, Dean D, Bernstein AD. A method of uniform stratification of risk for evaluating the results of surgery in acquired adult heart disease. Circulation 1989;79:I3–12.

  7. Bridgewater B, Neve H, Moat N, Hooper T, Jones M. Predicting operative risk for coronary artery surgery in the United Kingdom: a comparison of various risk prediction algorithms. Heart 1998;79:350–5.[Abstract/Free Full Text]

  8. Tu JV, Jaglal SB, Naylor CD. Multicentre validation of a risk index for mortality, intensive care unit stay and overall hospital length of stay after cardiac surgery. Steering Committee of the Provincial Adult Cardiac Care Network of Ontario. Circulation 1995;91:677–84.[Abstract/Free Full Text]

  9. Katz NM, Chase GA. Risks of cardiac operations for elderly patients: reduction of the age factor. Ann Thorac Surg 1997;63:1309–14.[Abstract/Free Full Text]

  10. Salomon NW, Page US, Bigelow JC, Krause AH, Okies JE, Metzdorff MT. Coronary artery bypass grafting in elderly patients: comparative results in a consecutive series of 469 patients older than 75 years. J Thorac Cardiovasc Surg 1991;101:209–18.[Abstract]

  11. Horvath KA, DiSesa VJ, Peigh PS, Couper GS, Collins JJ Jr, Cohn LH. Favourable results of coronary artery bypass grafting in patients older than 75 years. J Thorac Cardiovasc Surg 1990;99:92–6.[Abstract]

  12. Edwards FH, Clark RE, Schwartz M. Impact of internal mammary artery conduits on operative mortality in coronary revascularization. Ann Thorac Surg 1994;57:27–32.[Abstract]

  13. He GW, Acuff TE, Ryan WH, Bowman RT, Douthit MB, Mack MJ. Determinants of operative mortality in elderly patients undergoing coronary artery bypass grafting. Emphasis on the influence of internal mammary artery grafting on mortality and morbidity. J Thorac Cardiovasc Surg 1994;108:73–81.[Abstract/Free Full Text]

  14. Wynne-Jones K, Jackson M, Grotte G, Bridgewater B. Limitations of the Parsonnet score for measuring risk stratified mortality in the north west of England. Heart 2000;84:71–8.[Abstract/Free Full Text]

  15. Poloniecki J, Valencia O, Littlejohns P. Cumulative risk adjusted mortality charts for detecting changes in death rates: observational study of heart surgery. BMJ 1998;316:1697–700.[Abstract/Free Full Text]

  16. Khan SS, Kupfer JM, Matloff JM, Tsai TP, Nessim S. Interaction of age and preoperative risk factors in predicting operative mortality for coronary bypass surgery. Circulation 1992;86:186–90.

  17. Lahey SJ, Borlase BC, Lavin PR, Levitsky S. Preoperative risk factors that predict hospital length of stay in coronary artery bypass patients > 60 years old. Circulation 1992;86:II181–5.

  18. Peigh PS, Swartz MT, Vaca KJ, Lohmann DP, Naunheim KS. Effect of advancing age on cost and outcome of coronary artery bypass grafting. Ann Thorac Surg 1994;58:II1362–7.

  19. Katz NM, Ahmed SW, Clark BK, Wallace RB. Predictors of length of hospitalization after cardiac surgery. Ann Thorac Surg 1988;45:656–60.[Abstract]




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