Ann Thorac Surg 2006;81:2115-2120
© 2006 The Society of Thoracic Surgeons
Original article: Cardiovascular
Severity of Angina as a Predictor of Quality of Life Changes Six Months After Coronary Artery Bypass Surgery
Vladan M. Peric, MD
a
,
*
,
Milorad D. Borzanovic, MD
b
,
Radojica V. Stolic, MD
a
,
Aleksandar N. Jovanovic, MD
a
,
Sasa R. Sovtic, MD
a
a University of Pristina, School of Medicine, Internal Clinic, Kosovska Mitrovica
b Dedinje Cardiovascular Institute, Belgrade, Serbia and Montenegro
Accepted for publication January 9, 2006.
* Address correspondence to Dr Peric, University of Pristina, Faculty of Medicine, Internal Clinic, Kosova, Serbia and Montenegro. (Email: drperic{at}eunet.yu).
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Abstract
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BACKGROUND: Although the fact that chest pain has a negative influence on the quality of life is well known, it is not completely clear whether the preoperative severity of angina can be a predictor of the quality of life change after coronary artery bypass grafting (CABG).
METHODS: We studied 243 consecutive patients who underwent elective CABG. The Nottingham Health Profile Questionnaire part 1 was used as the model for determination of quality of life. We distributed the questionnaire to all patients before and six months after coronary artery bypass surgery. Two hundred and twenty-six patients filled in the postoperative questionnaire. Severity of angina was estimated by Canadian Cardiovascular Society (CCS) classification of angina.
RESULTS: Quality of life (before and after CABG surgery) in all sections was significantly worse in patients with higher CCS angina class (p < 0.001). The CCS angina class was 1.89 ± 0.97 at baseline and improved to 0.46 ± 0.75 (p < 0.001) after CABG. Six months after the operation, quality of life significantly improved in patients with all classes of angina (p < 0.01). The improvement in quality of life was related to higher CCS angina class in sections of physical mobility (r = 0.4, p < 0.001), energy (r = 0.31, p < 0.001), and pain (r = 0.48, p < 0.001). High CCS angina class before CABG was an independent predictor of quality of life improvement after coronary artery bypass surgery in sections of physical mobility (p = 0.005; odds ratio [OR] = 2.11; confidence interval [CI] 1.25 to 3.55), energy (p = 0.021; OR = 1.77; CI 1.09 to 2.87), and pain (p < 0.001; OR = 3.99; CI 2.2 to 7.22).
CONCLUSIONS: Patients with higher CCS angina class had worse preoperative and postoperative quality of life. Patients with preoperative higher CCS angina class had greater improvement in sections of physical mobility, energy, and pain. High CCS angina class before CABG was the independent predictor of quality of life improvement six months after CABG.
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Introduction
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The current wide use of coronary artery by-pass surgery (CABG) could be explained by its efficiency in the removal of angina and prolonged survival in certain categories of patients. In patients with less improved coronary disease, the decision for performing an operation was based mainly on an improvement of angina and quality of life (QOL) of patients. The removal of angina during 5 and 10 years was recorded in 83% and 63% of patients, retrospectively [1]. In some studies, appearance and severity of angina were used as criteria (beside the other indexes) for an estimation of the QOL [2]. Today, it is acceptable that the estimation of the QOL should be based on the analysis of data received from the questionnaires that already had confirmed their efficiency in clinical examinations. It is well known that chest pain has a negative influence on the QOL, but it is not completely clear whether the preoperative severity of angina can be a predictor of the QOL change after CABG. Considering the complex relation between angina before CABG and QOL after CABG, the following aims of the examinations were set.
- • To examine the preoperative quality of life in patients with different severity of angina;
- • to examine the quality of life change six months after CABG in patients with different severity of angina;
- • to examine the relationship between preoperative severity of angina and the QOL changes six months after coronary artery by-pass surgery;
- • to examine the presumption that the severity of angina can be the predictor of QOL change six months after coronary artery by-pass surgery.
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Patients and Methods
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A group of 243 consecutive patients who underwent elective CABG on the Dedinje Cardiovascular Institute, Belgrade (Serbia and Montenegro), prospectively was studied between February and May 2002. Individual consent for the participation in the scientific study was obtained from all examined patients. On February 10, 2002, the Ethical Committee of Dedinje Cardiovascular Institute approved accomplishment of the study. The Nottingham Health Profile Questionnaire (NHP) part 1 was used as the model for QOL determination [3]. It was written originally in English and it underwent rigorous translation into Serbian and linguistic validation. The 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 the Thurstone method of paired compares, to every positive answer [4]. A higher score indicates a higher level of dysfunction and worse QOL. We distributed the questionnaire to all patients before CABG and six months after CABG. Two hundred twenty-six patients filled in the postoperative questionnaire.
There were 26 analyzed preoperative and postoperative variables: 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, Canadian Cardiovascular Society (CCS) classification of angina, functional class of dyspnea according to New York Heart Association classification (NYHA), ejection fraction, segmental mobility of the left ventricle walls, associated illness, European system for cardiac operative risk evaluation (EuroSCORE), type of surgical procedure, number and type of implanted grafts, earlier heart surgery, and postoperative complications. All data before and after CAGB were gathered by the same examiner.
Statistical Analysis
The data are presented as mean ± standard deviation. For determining relation between preoperative (and postoperative) severity of angina and the QOL, Spearman correlation was performed. The preoperative and postoperative scores of QOL in patients with differences in CCS angina class were compared using the Wilcoxon matched-pairs rank test. We compared preoperative and postoperative results with referent values, which were obtained by means of general population examinations [5] and applied to sex and age distribution of the examined patients. Individual preoperative versus 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 difference in CCS angina class six months before and after CABG was also tested by the Wilcoxon matched-pairs rank test.
The relationship between preoperative severity of angina and the QOL changes six months after coronary artery bypass 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. Every single category of variables (a 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. The CCS class III and IV angina were treated as the same group in statistical analysis as well as in graphics and tables, because there was a small number of patients with CCS class IV.
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Results
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Among the patients who underwent surgery, 80% were males, aged 58.3 ± 8.2, and 20% were females, aged 61.6 ± 6.1. Mean scores of QOL before CABG for different sections of NHP part 1, in patients with different severity of angina, are shown in Table 1. Patients with higher CCS angina class showed statistically significant worse NHP 1 scores within the preoperative period in all sections of QOL compared with patients who had lower CCS angina class and those without angina (p < 0.001).
Comparing the average values of total NHP part 1 score before and six months after CABG, we found statistically significant improvement in QOL (p = 0.008 for CCS class I; p < 0.001 for the remaining angina class). In some angina classes (no angina and CCS class I) the postoperative QOL approached the referent values for patient's age and sex (Fig 1). The CCS angina class were 1.9 ± 1.0 at baseline and improved to 0.5 ± 0.7 (p < 0.001) after CABG. Preoperatively, most patients belonged to CCS class II angina (50%) and class III (24%). Six months after CABG, most patients were free from any angina difficulties (68%), while there were 20% estimated as CCS class I angina (Table 2). It has been reported that patients with higher angina class have worse preoperative QOL. Figure 2
shows the relationship between NHP part 1 score and severity of angina in patients before and after CABG (p < 0.001). As well as before CABG, patients with higher postoperative CCS angina class have worse postoperative QOL. Six months after the operation, the improvement in QOL was related to higher CCS angina class in the section of physical mobility (r = 0.4, p < 0.001), energy (r = 0.31, p < 0.001), and pain (r = 0.48, p < 0.001). In the other sections, the severity of angina was not significantly related to the level of QOL changes after CABG (Table 3). The level of changes in the diverse sections of QOL in patients with different classes of angina is shown in Figure 3.
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Fig 1. Mean NHP part 1 score in patients with different severity of angina before and after CABG, compared with expected scores for age and sex (p = 0.008 for CCS I; p < 0.001 for other severity of angina). Black bar = before CABG; dark grey bar = after CABG; light grey bar = expected scores. (CABG = coronary artery bypass grafting; CCS = Canadian Cardiovascular Society classification of angina; NHP = Nottingham Health Profile questionnaire.)
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Table 3. Correlation Between Preoperative Class of Angina Pectoris and Quality of Life Change Six Months After Coronary Artery Bypass Graft Surgery
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In order to find independent predictors of QOL changes we performed the univariate and multivariate logistic regression tests. After univariate logistic regression, severity of angina in all sections was appropriate to be included in multivariate logistic regression. Multivariate logistic regression showed that the serious chest pain is an independent predictor of QOL improvement in sections of physical mobility (p = 0.005; odds ratio [OR] =2.11; confidence interval [CI] 1.25 to 3.55), energy (p = 0.02; OR = 1.77; CI 1.09 to 2.87), and pain (p < 0.001; OR=3.99; CI 2.2 to 7.22) (Table 4).
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Comment
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Chest pain is the main reason for coronary patients to refer to the doctor. Removal or decreasing of angina, after some therapeutic treatment, is the greatest benefit that a coronary patient can have. The wide use of CABG was primary aimed on removal of angina and improved survival.
To monitor the positive effects of CABG usually means observing the reducing of angina difficulties, decreasing the use of nitrates, and increasing physical persistence, as standards for QOL. Although those standards represent the main somatic effects of myocardium revascularization, they hardly can be equivalent to QOL. Quality of life is determined by personal perceptions of symptoms and physical and mental functional abilities. The 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.
Pain and fear of new attacks significantly limit daily activities. Before CABG, patients with higher CCS angina class have worse QOL in all its sections (Table 1). Most authors who examined QOL in patients with different severity of angina reported that the bad quality of life was associated with the presence of serious chest pain [6–8]. Patients with angina show a lack of energy, sleeping problems, and reduced physical mobility compared with the normal population [8]. In this study, patients with higher severity of angina show worse results in physical mobility, higher degrees of social isolation and emotional unstableness, a lack of energy necessary for daily activities, and worse sleeping compared with patients with no angina and those with lower degrees of angina. In coronary patients with chest pain there is an occurrence of anxiousness and depression that substantially disorders QOL [9]. A large number of authors reported about significant improvement of QOL with the help of CABG [10, 11]. A year after CABG, the QOL of patients was significantly better than before the operation and those changes were directly connected with the reduction of angina [12]. Six months after CABG, we found an average improvement of quality of life in all CCS angina classes of patients (Fig 1). During the same period, we also found an improved symptomatology in patients; frequency and intensity of angina was significantly lower compared with the preoperative period (Table 2).
With increased CCS angina class there was increased NHP part 1 score (QOL got worse) six months before and after CABG. Patients with no angina have QOL proximate to average population standards for age and sex (Fig 2). This is important because six months after CABG most patients are set free from angina (Table 2). These results agree with findings of the Randomized Intervention Treatment of Angina study where the bad QOL was related to severity of angina both before and after revascularization procedures (CABG and coronary angioplasty). With a reduction of angina after revascularization, there was an improvement in all aspects of QOL. There is no difference in QOL between patients without angina and expected mean population norms. Patients with angina had significantly worse results compared with those with no angina, even when their pain was minimal [13]. High preoperative CCS angina class was related to higher improvement of QOL of patients for sections of physical mobility, energy, and pain six months after CABG (Table 3; Fig 3). High CCS angina is associated with intensive symptomatology and a large number of limitations that disorder the quality of life. By decreasing or removing angina after an operation, we have the reduction of previously mentioned limitations as well as a significant improvement of QOL of patients. After CABG, there is a benefit regarding QOL in patients with all angina class (Fig 1). However, there is the greatest benefit for patients with highest preoperative CCS angina class (Fig 3). That does not mean that six months after CABG they have better QOL compared with patients with lower preoperative angina class (Fig 1), but they only profit more after CABG compared with preoperative QOL. It is obvious the more QOL impaired preoperatively the more difficult it returns in normal range postoperatively. This is certainly, to some extent, caused by residual angina but other factors (such as irreversible myocardial damage caused by severe angina that could not be resolved by revascularization) may have influence. In a large study in Sweden it was also emphasized that the improvement of the QOL two years after CABG was related to severity of preoperative angina. The more symptomatic patients, and those with the greatest physical limitations, had the highest improvements in QOL [6].
The NHP questionnaire is the generic scale and it is specific not only for coronary disease, but for the wide scale of disturbances of QOL caused by numerous pathological states. The relationship between the severity of angina and QOL is doubtless, but one must not exclude the influence of comorbidity and other, additional factors (general life, social, economic, and political conditions) on the measures of the QOL.
The connection between severity of angina and QOL was clearly confirmed in most studies that analyzed this problem [7, 8, 13, 14]. However, this study showed that high angina class is the independent predictor of the QOL improvement six months after CABG for sections of physical mobility, energy, and pain. Besides, the high angina class was the most significant predictor (comparing with other predictors derived by multivariate analysis) of improvement of quality of life in the majority of sections (Table 4). The CCS angina class was not the predictor of QOL change for the remaining sections of QOL. In patients with no preoperative angina there is more frequent disorder of QOL after CABG compared with patients with angina [15]. When mortality or morbidity outcomes in clinical trials are less than clear-cut, the QOL has particular value as an outcome measure [16]. Independent from its influence on survival, CABG is potentially indicated to be the symptomatic therapy in the following cases: to reduce angina that occurs despite medicative therapy and to decrease the frequency of nonfatal consequences of coronary heart disease (infract, congestive heart failure, hospitalizations) [1]. It is thought that there is a much larger group of patients, where CABG can reduce anginal pain and improve QOL, compared with the group of patients where this operation leads to prolonged life. Considering the fact that only three patients were classified as CCS class IV of angina (Table 2), the conclusions of this study cannot be readily applicable to the patients with CCS class IV angina.
Finally, this study confirms the strong relationship between angina pectoris and poor QOL. After CABG, patients with the most intensive preoperative angina have the greatest benefits regarding the QOL changes. High CCS angina class is an independent predictor of QOL improvement six months after CABG. In patients with high CCS angina class, CABG should be recommended as a procedure that significantly improves QOL without ignoring an influence of operation on the survival of patients.
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Acknowledgments
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Special thanks to the patients and the staff of Dedinje Cardiovascular Institute–Belgrade.
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References
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Top
Abstract
Introduction
= before CABG; 
= after CABG; – – – = expected scores. (CABG = coronary artery bypass grafting; CCS = Canadian Cardiovascular Society classification of angina; NHP = Nottingham Health Profile questionnaire.)
= PM; 
= ER; 
= En; 
= Pain; 
= Sleep. (CABG = coronary artery bypass grafting; CCS = Canadian Cardiovascular Society classification of angina; En = energy; ER = emotional reaction; PM = physical mobility; QOL = quality of life; SI = social isolation.)