The relationship between EuroSCORE preoperative risk prediction and quality of life changes after coronary artery by-pass surgery
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a University of Pristina, Faculty of Medicine, Internal Clinic, Anri Didana bb, 28000 Kosovska Mitrovica, Serbia and Montenegro
b Dedinje Cardiovascular Institute, Belgrade, Serbia and Montenegro
Presented at the 53rd International Congress of the European Society for Cardiovascular Surgery, Ljubljana, Slovenia, June 2–5, 2004.
Abstract
Objective: To examine the relationship between preoperative risk prediction and the quality of life (QOL) changes six months after coronary artery by-pass surgery (CABG). Methods: From February to May 2002, we prospectively studied 243 consecutive patients, who underwent elective CABG. The Nottingham Health Profile Questionnaire (NHP) part 1 was used as the model for QOL determination. We distributed the questionnaire to all patients before CABG and six months after CABG. Two hundred and twenty-six patients filled in the postoperative questionnaire. We calculated the preoperative risk of death using the European System for Cardiac Operative Risk Evaluation (EuroSCORE). Results: Eighty-nine out of 243 (37%) patients were in low risk group, 108/243 (44%) were in medium risk group and 46/243 (19%) were in high risk group. Prior to CABG, higher EuroSCORE was related to poorer quality of life of the examinees (r=0.23, P<0.001). Six months after the operation, the improvement in QOL was related to higher EuroSCORE in section of energy (r=0.19, P=0.005). To determine the preoperative factors influencing the changes of QOL scores after CABG, we performed logistic regression, first by univariate analysis, and then by multivariate analysis. We analyzed 26 examined variables with potential influence on postoperative QOL. EuroSCORE was not the predictor of the QOL changes six months after CABG. Conclusions: Patients with higher EuroSCORE risk of death had worse preoperative QOL. Patients with higher EuroSCORE had greater improvement of QOL in section of energy. EuroSCORE was not the predictor of QOL changes after CABG.
Key Words: Quality of life; Preoperative risk prediction; Coronary artery by-pass surgery
1. Introduction
Numerous tables and scores for prediction of the preoperative risk and short- and long-term mortality after coronary artery by-pass surgery (CABG) were updated [1,2]. Preoperative risk stratification was defined as the possibility of predicting the outcome of a certain intervention, making the classification of the patients according to the severity of the illness. Based on that stratification, the expected postoperative mortality—which can be compared with the real mortality—is established, and, in that way, the effect of the surgical procedure can be determined.
The quality of life (QOL) represents a unique personal perception, e.g. a way of self-assessment of one's health status and non-medical aspects of life. As a medical entity, the QOL appeared in a medical publication in 1970, and in the past two decades, it was distinguished as an important attribute of the clinical examination and the medical care. When mortality or morbidity outcomes in clinical trials are less than clear-cut, the quality of life has particular value as an outcome measure [3].
The preoperative risk stratification and the QOL are widely examined individually, but the trials to establish an association between the two entities are rare.
2. Aims
Considering the results of various examinations and studies and no clear-cut association between preoperative risk stratification and the postoperative QOL, we established the following objectives of this study:
To study the preoperative QOL in patients with the diverse level of cardiac operative risk prediction.
To examine the relationship between preoperative risk prediction and the quality of life (QOL) changes six months after coronary artery by-pass surgery.
To examine the presumption that the preoperative risk can be the predictor of QOL change six months after coronary artery by-pass surgery.
3. Materials and methods
We prospectively studied 243 consecutive patients who underwent elective CABG on the Dedinje Cardiovascular Institute-Belgrade (Serbia and Montenegro), in the period of February–May 2002. The Nottingham Health Profile Questionnaire (NHP) part 1 was used as the model for QOL determination [4]. It was written originally in English, and underwent rigorous translation into Serbian and linguistic validation. NHP part 1 contains 38 subjective statements divided into six sections: physical mobility (PM), social isolation (SI), emotional reaction (ER), energy (En), pain and sleep. The scores of each section ranged from zero to 100, by adding the item weight, determined by Thurstone method of paired compares, to every positive answer [5]. A higher score indicates a higher level of dysfunction and worse quality of life. We distributed the questionnaire to all patients before CABG and six months after CABG. Two hundred and twenty-six patients filled in the postoperative questionnaire.
The analyzed preoperative and perioperative variables were: sex, age, marriage status, type of job, and actual working status, risk factors for the ischemic heart disease, the presence of valvular disease, preceding myocardial infarction(s), number of coronary vessels involved, risk factors for ischemic heart disease, functional class of angina according to Canadian Cardiology Society (CCS), functional class of dyspnea according to New York Heart Association classification (NYHA), ejection fraction, segmental mobility of the left ventricle walls, associated illness, EuroSCORE, type of surgical procedure, number and type of implanted grafts, earlier heart surgery, post-operative complications.
We calculated the preoperative risk of death using the European System for Cardiac Operative Risk Evaluation (EuroSCORE). EuroSCORE is the first model of pre-operative risk stratification which was made by the examining of European population. EuroSCORE is the scoring system that was created by a group of European authors [1,6]. It was made for the purpose of prediction of short-term mortality of the patients preparing for cardio-surgical procedures. Three groups of risk factors were identified: patient-related factors, cardiac-related factors and operation-related factors. According to these recommendations, three risk groups were defined: the low risk group (EuroSCORE 1–2), the medium risk group (EuroSCORE 3–5) and the high risk group (EuroSCORE 6 and higher).
4. Statistical analysis
The data are presented as mean±standard deviation. For determining the relation between preoperative QOL and the height of EuroSCORE, Spearman correlation was performed. The preoperative and postoperative scores for each section of QOL were compared using a Wilcoxon matched-pairs rank test. We compared preoperative and postoperative results of every QOL section with referent values, which were obtained by means of general population examinations [7], and applied to sex and age distribution of the examined patients. Individual preoperative vs. postoperative QOL were compared in order to identify the patients with improved QOL, those with worsened QOL, and the patients with no changes in postoperative QOL.
The relationship between EuroSCORE prediction of preoperative risk and quality of life changes after coronary artery by-pass surgery was determined by Spearman's correlation. The change in the QOL was calculated from the differences in preoperative and postoperative QOL for every section.
To determine the factors influencing the change of QOL after CABG, with the dependent variable being binary (improved or worsened), we performed logistic regression. During the examination of predictors of improvement, patients with no changes in postoperative QOL were considered together with the patients with worsening QOL (and vice versa). Every category of variables (total of 26) was analyzed in every section of QOL, using the univariate logistic regression. Variables with a level of significance less than or equal to 0.20 in the univariate analysis were included in the multivariate logistic regression.
Considering that NHP part 1 consists of six sections which we treated separately, in order to decrease the likelihood of statistical error, we took P-value0.008 (0.05/6=0.0083) as statistically significant difference.
5. Results
The preoperative features of examined population are shown in the Table 1. Among the patients who underwent surgery, 80% were males, aged 58.3±8.2, and 48 (20%) were females, aged 61.6±6.1. Data show that the 89/243 (37%) of patients were in low risk group, 108/243 (44%) were in medium risk group and 46/243 (19%) were in high risk group (according to the EuroSCORE system). The average values of preoperative scores QOL in the examined groups are shown in Table 2.
We compared the preoperative QOL in patients with various preoperative risks. Patients with higher EuroSCORE had significantly worse scores in the sections of physical mobility (r=0.24, P<0.001), energy (r=0.27, P<0.001) and worse total QOL (r=0.23, P<0.001) (Table 3).
Comparing the average values of NHP score for every QOL section before and six months after CABG, we found statistically highly significant improvement in QOL in all sections regarding the NHP part 1 (P=0.008 for section SI; P<0.001 for the remaining sections of NHP part 1). In some sections, the postoperative QOL approached the referent values for patient's age and sex (Fig. 1).
If the intersection preoperative and postoperative QOL (total NHP 1 score) in every patient is shown by a point in a diagram (according to the recommendation of Gill et al.) [8], all the points that lie below the bias present the patients in which QOL is improved, and the points above the bias present the patients in which QOL is worsened, while the patients in which there are no changes in QOL after the operation are shown by points on the bias (Fig. 2). In most patients, improvement in QOL can be noticed.
Tracking the changes in total QOL illustrated by NHP part 1, we concluded that the improvement was found in 85% of patients, and worsening in 15% (Fig. 3).
Six months after the operation, the improvement in QOL was related to higher EuroSCORE in section of energy (r=0.19, P=0.005). In the other sections, the level of operative risk, defined by EuroSCORE, was not significantly related to the level of QOL changes after CABG (Table 4). The level of changes in the diverse sections of QOL in patients with different EuroSCORE is shown in Fig. 4.
To determine the preoperative factors influencing the changes of QOL scores after CABG, we performed logistic regression, first by univariate analysis and then by multivariate analysis. EuroSCORE has not been the independent predictor of the QOL changes six months after CABG. These results are not shown here, due to abundance of data.
6. Discussion
Since the 1970s, the measurement of quality of life has grown from a small cottage industry to a large academic enterprise [8]. Provocative claims about ‘cold clinical science giving scant attention to the patient as a human being’ underlie a wide-ranging reaction that QOL is a positive step forward in clinical studies [9]. Good QOL means the ability of a person to function in a normal way and to be satisfied with participation in daily activities. The ability to perform daily activities includes preserved physical mobility, independence, amount of energy sufficient for daily activities, self-care, social contacts, emotional stability and absence of pain, relief of other difficulties, adequate sleeping and rest.
It is well known that high-risk patients often stand to benefit most from surgery in terms of prognosis (the cardiac surgical paradox). However, it remains unclear up to date, whether the patients with increased operative risk have more benefit after the operation and in view of the expected quality of life.
We used the model of the preoperative risk stratification that was composed of the results of the examination of European population (where our examined patients belong). Patients with higher EuroSCORE have worse total QOL and QOL in the physical mobility section and energy section before CABG (Table 3). These results are understandable regarding the fact that higher preoperative risk means more complicated disease, with more limitations.
There are numerous reports of improvement of QOL after CABG; our results are concordant with that (Fig. 1). However, compared with other studies, the examined patients in this study had higher NHP scores (worse QOL) before operation and after operation as well [10]. QOL depends on general life conditions, social, economic and political conditions in certain society. The results could be explained by poor life conditions during the transition and the bad social, economic and unstable political situation in our country at the time in which these results were obtained.
High preoperative risk always puts the physicians in a dilemma whether to operate or not. From the beginning of studies of QOL as the measure of the CABG outcome, this problem gained new dimensions. Namely, former studies showed that the most remarkable QOL improvement is often noted in patients with the greatest risk [11]. Our results are partly concordant. The patients with higher EuroSCORE had better improvement in QOL in the period of six months after CABG in the section of energy (Table 4 and Fig. 4).
Up to date, the relation of high preoperative risk and quality of life after CABG was often studied in older individuals—who already have higher risk due to co-morbidity and age. Nowadays, there is the increment of number of older patients who underwent CABG [12]. They usually have more extensive coronary artery disease and worse total preoperative state. Most reports showed that older patients (regarding the acceptable operative risk) have most benefits after CABG, comparing to the initial QOL [13]. This is concordant with our results that show most visible QOL improvement after CABG in patients with the most damaged initial QOL. However, some reports show that older persons tend to have lesser functional improvement after CABG, comparing with younger patients [14]. These results are not due only to higher preoperative risk in older patients. Studies in QOL in older patients as the high-risk population, represent the limited point of view.
Small number of studies directly relates level of operative risk and QOL after CABG. Radovanovic et al. examined the relation between QOL and expected operative risk of open-heart intervention, defined by Parsonnet's method. The negative correlation between the level of operative risk and the average preoperative QOL index was found. There was no correlation between QOL or QOL improvement and the level of operative risk in the 6-month period after CABG [11].
In this study, there is a statistically significant correlation between EuroSCORE and the change in QOL in the section of energy. However, the found correlation between the height of preoperative risk and the change in QOL for the section of energy is extremely small (Table 4). For that reason, in everyday hospital practice, EuroSCORE cannot serve for prediction of the change of quality of life, which was also confirmed by performed logistic regression.
We conclude that patients with the higher EuroSCORE risk of death had the worse total preoperative QOL and QOL in section physical mobility and energy. Patients with the higher EuroSCORE had the higher improvement of QOL in section energy six months after CABG. Although the EuroSCORE showed excellent results in the early mortality prediction after CABG, it is obvious that it cannot be the predictor of QOL changes after CABG.
References
Nashef SA, Roques F, Michel P, Gauducheau E, Lemeshow S, Salamon R. European system for cardiac operative risk evaluation (EuroSCORE). Eur J Cardiothorac Surg 1999;16:9–13.
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–I12.
Wenger NK, Mattson ME, Furberg CD, Elinson J. Assessment of quality of life in clinical trials of cardiovascular therapies. Am J Cardiol 1984;54:908–913.
Hunt SM, McKenna SP, McEwen J, Williams J, Papp E. The Nottingham Health Profile: subjective health status and medical consultations. Soc Sci Med 1981;15:221–229.
McKenna SP, Hunt SM, McEwen J. Weighting the seriousness of perceived health problems using Thurstone's method of paired comparisons. Int J Epidemiol 1981;10:93–97.
Roques F, Nashef SA, Michel P, Gauducheau E, de Vincentiis C, Baudet E, Cortina J, David M, Faichney A, Gabrielle F, Gams E, Harjula A, Jones MT, Pintor PP, Salamon R, Thulin L. Risk factors and outcome in European cardiac surgery: analysis of the EuroSCORE multinational database of 19030 patients. Eur J Cardiothorac Surg 1999;15:816–823.
Hunt SM, McEwen J, McKenna SP. Perceived health: age and sex comparisons in a community. J Epidemiol Community Health 1984;38:156–160.
Gill TM, Feinstein AR. A critical appraisal of the quality of life measurements. JAMA 1994;272:619–626.
Pocock SJ. A perspective on the role of quality of life assessment in clinical trials. Control Clin Trials 1991;12:257S–265S.
Chocron S, Etievent JP, Viel JF, Dussaucy A, Alwan K, Neidhardt M, Schipman N. Prospective study of quality of life before and after open heart operations. Ann Thorac Surg 1996;61:153–157.
Radovanovi N, Jakovljevi DJ. Long-term survival and quality of life after open heart surgery. Novi Sad 2003;79–102.
Ivanov J, Weisel RD, David TE, Naylor CD. Fifteen-year trends in risk severity and operative mortality in elderly patients undergoing coronary artery bypass graft surgery. Circulation 1998;97:673–680.
Peterson ED, Cowper PA, Jollis JG, Bebchuk JD, DeLong ER, Muhlbaier LH, Mark DB, Pryor DB. Outcomes of coronary artery bypass graft surgery in 24,461 patients aged 80 years or older. Circulation 1995;92:II85–II91.
Conaway DG, House J, Bandt K, Hayden L, Borkon AM, Spertus JA. The elderly: health status benefits and recovery of function one year after coronary artery bypass surgery. J Am Coll Cardiol 2003;42:1421–1426.(Vladan Peric, Milorad Bor)
b Dedinje Cardiovascular Institute, Belgrade, Serbia and Montenegro
Presented at the 53rd International Congress of the European Society for Cardiovascular Surgery, Ljubljana, Slovenia, June 2–5, 2004.
Abstract
Objective: To examine the relationship between preoperative risk prediction and the quality of life (QOL) changes six months after coronary artery by-pass surgery (CABG). Methods: From February to May 2002, we prospectively studied 243 consecutive patients, who underwent elective CABG. The Nottingham Health Profile Questionnaire (NHP) part 1 was used as the model for QOL determination. We distributed the questionnaire to all patients before CABG and six months after CABG. Two hundred and twenty-six patients filled in the postoperative questionnaire. We calculated the preoperative risk of death using the European System for Cardiac Operative Risk Evaluation (EuroSCORE). Results: Eighty-nine out of 243 (37%) patients were in low risk group, 108/243 (44%) were in medium risk group and 46/243 (19%) were in high risk group. Prior to CABG, higher EuroSCORE was related to poorer quality of life of the examinees (r=0.23, P<0.001). Six months after the operation, the improvement in QOL was related to higher EuroSCORE in section of energy (r=0.19, P=0.005). To determine the preoperative factors influencing the changes of QOL scores after CABG, we performed logistic regression, first by univariate analysis, and then by multivariate analysis. We analyzed 26 examined variables with potential influence on postoperative QOL. EuroSCORE was not the predictor of the QOL changes six months after CABG. Conclusions: Patients with higher EuroSCORE risk of death had worse preoperative QOL. Patients with higher EuroSCORE had greater improvement of QOL in section of energy. EuroSCORE was not the predictor of QOL changes after CABG.
Key Words: Quality of life; Preoperative risk prediction; Coronary artery by-pass surgery
1. Introduction
Numerous tables and scores for prediction of the preoperative risk and short- and long-term mortality after coronary artery by-pass surgery (CABG) were updated [1,2]. Preoperative risk stratification was defined as the possibility of predicting the outcome of a certain intervention, making the classification of the patients according to the severity of the illness. Based on that stratification, the expected postoperative mortality—which can be compared with the real mortality—is established, and, in that way, the effect of the surgical procedure can be determined.
The quality of life (QOL) represents a unique personal perception, e.g. a way of self-assessment of one's health status and non-medical aspects of life. As a medical entity, the QOL appeared in a medical publication in 1970, and in the past two decades, it was distinguished as an important attribute of the clinical examination and the medical care. When mortality or morbidity outcomes in clinical trials are less than clear-cut, the quality of life has particular value as an outcome measure [3].
The preoperative risk stratification and the QOL are widely examined individually, but the trials to establish an association between the two entities are rare.
2. Aims
Considering the results of various examinations and studies and no clear-cut association between preoperative risk stratification and the postoperative QOL, we established the following objectives of this study:
To study the preoperative QOL in patients with the diverse level of cardiac operative risk prediction.
To examine the relationship between preoperative risk prediction and the quality of life (QOL) changes six months after coronary artery by-pass surgery.
To examine the presumption that the preoperative risk can be the predictor of QOL change six months after coronary artery by-pass surgery.
3. Materials and methods
We prospectively studied 243 consecutive patients who underwent elective CABG on the Dedinje Cardiovascular Institute-Belgrade (Serbia and Montenegro), in the period of February–May 2002. The Nottingham Health Profile Questionnaire (NHP) part 1 was used as the model for QOL determination [4]. It was written originally in English, and underwent rigorous translation into Serbian and linguistic validation. NHP part 1 contains 38 subjective statements divided into six sections: physical mobility (PM), social isolation (SI), emotional reaction (ER), energy (En), pain and sleep. The scores of each section ranged from zero to 100, by adding the item weight, determined by Thurstone method of paired compares, to every positive answer [5]. A higher score indicates a higher level of dysfunction and worse quality of life. We distributed the questionnaire to all patients before CABG and six months after CABG. Two hundred and twenty-six patients filled in the postoperative questionnaire.
The analyzed preoperative and perioperative variables were: sex, age, marriage status, type of job, and actual working status, risk factors for the ischemic heart disease, the presence of valvular disease, preceding myocardial infarction(s), number of coronary vessels involved, risk factors for ischemic heart disease, functional class of angina according to Canadian Cardiology Society (CCS), functional class of dyspnea according to New York Heart Association classification (NYHA), ejection fraction, segmental mobility of the left ventricle walls, associated illness, EuroSCORE, type of surgical procedure, number and type of implanted grafts, earlier heart surgery, post-operative complications.
We calculated the preoperative risk of death using the European System for Cardiac Operative Risk Evaluation (EuroSCORE). EuroSCORE is the first model of pre-operative risk stratification which was made by the examining of European population. EuroSCORE is the scoring system that was created by a group of European authors [1,6]. It was made for the purpose of prediction of short-term mortality of the patients preparing for cardio-surgical procedures. Three groups of risk factors were identified: patient-related factors, cardiac-related factors and operation-related factors. According to these recommendations, three risk groups were defined: the low risk group (EuroSCORE 1–2), the medium risk group (EuroSCORE 3–5) and the high risk group (EuroSCORE 6 and higher).
4. Statistical analysis
The data are presented as mean±standard deviation. For determining the relation between preoperative QOL and the height of EuroSCORE, Spearman correlation was performed. The preoperative and postoperative scores for each section of QOL were compared using a Wilcoxon matched-pairs rank test. We compared preoperative and postoperative results of every QOL section with referent values, which were obtained by means of general population examinations [7], and applied to sex and age distribution of the examined patients. Individual preoperative vs. postoperative QOL were compared in order to identify the patients with improved QOL, those with worsened QOL, and the patients with no changes in postoperative QOL.
The relationship between EuroSCORE prediction of preoperative risk and quality of life changes after coronary artery by-pass surgery was determined by Spearman's correlation. The change in the QOL was calculated from the differences in preoperative and postoperative QOL for every section.
To determine the factors influencing the change of QOL after CABG, with the dependent variable being binary (improved or worsened), we performed logistic regression. During the examination of predictors of improvement, patients with no changes in postoperative QOL were considered together with the patients with worsening QOL (and vice versa). Every category of variables (total of 26) was analyzed in every section of QOL, using the univariate logistic regression. Variables with a level of significance less than or equal to 0.20 in the univariate analysis were included in the multivariate logistic regression.
Considering that NHP part 1 consists of six sections which we treated separately, in order to decrease the likelihood of statistical error, we took P-value0.008 (0.05/6=0.0083) as statistically significant difference.
5. Results
The preoperative features of examined population are shown in the Table 1. Among the patients who underwent surgery, 80% were males, aged 58.3±8.2, and 48 (20%) were females, aged 61.6±6.1. Data show that the 89/243 (37%) of patients were in low risk group, 108/243 (44%) were in medium risk group and 46/243 (19%) were in high risk group (according to the EuroSCORE system). The average values of preoperative scores QOL in the examined groups are shown in Table 2.
We compared the preoperative QOL in patients with various preoperative risks. Patients with higher EuroSCORE had significantly worse scores in the sections of physical mobility (r=0.24, P<0.001), energy (r=0.27, P<0.001) and worse total QOL (r=0.23, P<0.001) (Table 3).
Comparing the average values of NHP score for every QOL section before and six months after CABG, we found statistically highly significant improvement in QOL in all sections regarding the NHP part 1 (P=0.008 for section SI; P<0.001 for the remaining sections of NHP part 1). In some sections, the postoperative QOL approached the referent values for patient's age and sex (Fig. 1).
If the intersection preoperative and postoperative QOL (total NHP 1 score) in every patient is shown by a point in a diagram (according to the recommendation of Gill et al.) [8], all the points that lie below the bias present the patients in which QOL is improved, and the points above the bias present the patients in which QOL is worsened, while the patients in which there are no changes in QOL after the operation are shown by points on the bias (Fig. 2). In most patients, improvement in QOL can be noticed.
Tracking the changes in total QOL illustrated by NHP part 1, we concluded that the improvement was found in 85% of patients, and worsening in 15% (Fig. 3).
Six months after the operation, the improvement in QOL was related to higher EuroSCORE in section of energy (r=0.19, P=0.005). In the other sections, the level of operative risk, defined by EuroSCORE, was not significantly related to the level of QOL changes after CABG (Table 4). The level of changes in the diverse sections of QOL in patients with different EuroSCORE is shown in Fig. 4.
To determine the preoperative factors influencing the changes of QOL scores after CABG, we performed logistic regression, first by univariate analysis and then by multivariate analysis. EuroSCORE has not been the independent predictor of the QOL changes six months after CABG. These results are not shown here, due to abundance of data.
6. Discussion
Since the 1970s, the measurement of quality of life has grown from a small cottage industry to a large academic enterprise [8]. Provocative claims about ‘cold clinical science giving scant attention to the patient as a human being’ underlie a wide-ranging reaction that QOL is a positive step forward in clinical studies [9]. Good QOL means the ability of a person to function in a normal way and to be satisfied with participation in daily activities. The ability to perform daily activities includes preserved physical mobility, independence, amount of energy sufficient for daily activities, self-care, social contacts, emotional stability and absence of pain, relief of other difficulties, adequate sleeping and rest.
It is well known that high-risk patients often stand to benefit most from surgery in terms of prognosis (the cardiac surgical paradox). However, it remains unclear up to date, whether the patients with increased operative risk have more benefit after the operation and in view of the expected quality of life.
We used the model of the preoperative risk stratification that was composed of the results of the examination of European population (where our examined patients belong). Patients with higher EuroSCORE have worse total QOL and QOL in the physical mobility section and energy section before CABG (Table 3). These results are understandable regarding the fact that higher preoperative risk means more complicated disease, with more limitations.
There are numerous reports of improvement of QOL after CABG; our results are concordant with that (Fig. 1). However, compared with other studies, the examined patients in this study had higher NHP scores (worse QOL) before operation and after operation as well [10]. QOL depends on general life conditions, social, economic and political conditions in certain society. The results could be explained by poor life conditions during the transition and the bad social, economic and unstable political situation in our country at the time in which these results were obtained.
High preoperative risk always puts the physicians in a dilemma whether to operate or not. From the beginning of studies of QOL as the measure of the CABG outcome, this problem gained new dimensions. Namely, former studies showed that the most remarkable QOL improvement is often noted in patients with the greatest risk [11]. Our results are partly concordant. The patients with higher EuroSCORE had better improvement in QOL in the period of six months after CABG in the section of energy (Table 4 and Fig. 4).
Up to date, the relation of high preoperative risk and quality of life after CABG was often studied in older individuals—who already have higher risk due to co-morbidity and age. Nowadays, there is the increment of number of older patients who underwent CABG [12]. They usually have more extensive coronary artery disease and worse total preoperative state. Most reports showed that older patients (regarding the acceptable operative risk) have most benefits after CABG, comparing to the initial QOL [13]. This is concordant with our results that show most visible QOL improvement after CABG in patients with the most damaged initial QOL. However, some reports show that older persons tend to have lesser functional improvement after CABG, comparing with younger patients [14]. These results are not due only to higher preoperative risk in older patients. Studies in QOL in older patients as the high-risk population, represent the limited point of view.
Small number of studies directly relates level of operative risk and QOL after CABG. Radovanovic et al. examined the relation between QOL and expected operative risk of open-heart intervention, defined by Parsonnet's method. The negative correlation between the level of operative risk and the average preoperative QOL index was found. There was no correlation between QOL or QOL improvement and the level of operative risk in the 6-month period after CABG [11].
In this study, there is a statistically significant correlation between EuroSCORE and the change in QOL in the section of energy. However, the found correlation between the height of preoperative risk and the change in QOL for the section of energy is extremely small (Table 4). For that reason, in everyday hospital practice, EuroSCORE cannot serve for prediction of the change of quality of life, which was also confirmed by performed logistic regression.
We conclude that patients with the higher EuroSCORE risk of death had the worse total preoperative QOL and QOL in section physical mobility and energy. Patients with the higher EuroSCORE had the higher improvement of QOL in section energy six months after CABG. Although the EuroSCORE showed excellent results in the early mortality prediction after CABG, it is obvious that it cannot be the predictor of QOL changes after CABG.
References
Nashef SA, Roques F, Michel P, Gauducheau E, Lemeshow S, Salamon R. European system for cardiac operative risk evaluation (EuroSCORE). Eur J Cardiothorac Surg 1999;16:9–13.
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–I12.
Wenger NK, Mattson ME, Furberg CD, Elinson J. Assessment of quality of life in clinical trials of cardiovascular therapies. Am J Cardiol 1984;54:908–913.
Hunt SM, McKenna SP, McEwen J, Williams J, Papp E. The Nottingham Health Profile: subjective health status and medical consultations. Soc Sci Med 1981;15:221–229.
McKenna SP, Hunt SM, McEwen J. Weighting the seriousness of perceived health problems using Thurstone's method of paired comparisons. Int J Epidemiol 1981;10:93–97.
Roques F, Nashef SA, Michel P, Gauducheau E, de Vincentiis C, Baudet E, Cortina J, David M, Faichney A, Gabrielle F, Gams E, Harjula A, Jones MT, Pintor PP, Salamon R, Thulin L. Risk factors and outcome in European cardiac surgery: analysis of the EuroSCORE multinational database of 19030 patients. Eur J Cardiothorac Surg 1999;15:816–823.
Hunt SM, McEwen J, McKenna SP. Perceived health: age and sex comparisons in a community. J Epidemiol Community Health 1984;38:156–160.
Gill TM, Feinstein AR. A critical appraisal of the quality of life measurements. JAMA 1994;272:619–626.
Pocock SJ. A perspective on the role of quality of life assessment in clinical trials. Control Clin Trials 1991;12:257S–265S.
Chocron S, Etievent JP, Viel JF, Dussaucy A, Alwan K, Neidhardt M, Schipman N. Prospective study of quality of life before and after open heart operations. Ann Thorac Surg 1996;61:153–157.
Radovanovi N, Jakovljevi DJ. Long-term survival and quality of life after open heart surgery. Novi Sad 2003;79–102.
Ivanov J, Weisel RD, David TE, Naylor CD. Fifteen-year trends in risk severity and operative mortality in elderly patients undergoing coronary artery bypass graft surgery. Circulation 1998;97:673–680.
Peterson ED, Cowper PA, Jollis JG, Bebchuk JD, DeLong ER, Muhlbaier LH, Mark DB, Pryor DB. Outcomes of coronary artery bypass graft surgery in 24,461 patients aged 80 years or older. Circulation 1995;92:II85–II91.
Conaway DG, House J, Bandt K, Hayden L, Borkon AM, Spertus JA. The elderly: health status benefits and recovery of function one year after coronary artery bypass surgery. J Am Coll Cardiol 2003;42:1421–1426.(Vladan Peric, Milorad Bor)