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Ann Thorac Surg 2002;74:689-693
© 2002 The Society of Thoracic Surgeons

Original article: cardiovascular

In the eye of both patient and spouse: memory is poor 1 to 2 years after coronary bypass and angioplasty

Cecilia Bergh, MS*a, Martin Bäckström, PhDb, Henrik Jönsson, MD, PhDa, Lars Havinder, MSb, Per Johnsson, MD, PhDa

a Heart and Lung Center, Lund University Hospital, Lund, Sweden
b Department of Psychology, Lund University, Lund, Sweden

Accepted for publication April 24, 2002.

* Address reprint requests to Cecilia Bergh, Dept of Coronary Artery Disease, Heart and Lung Center, Lund University Hospital, SE-221 85 Lund, Sweden
e-mail: cecilia.bergh{at}skane.se


   Abstract
Top
 Abstract
Introduction
 Material and methods
 Results
 Comment
 Acknowledgments
 References
 
Background. The study aimed to investigate patient and spouse perception of cognitive functioning 1 to 2 years after coronary artery bypass grafting.

Methods. Seventy-six married patients who had undergone coronary artery bypass grafting were selected and sex- and age-matched with 75 concurrent married patients who had undergone percutaneous transluminal coronary angioplasty. Couples received a letter of explanation and then completed telephone interviews. Forty-seven questions assessed memory, concentration, general health, social functioning, and emotional state. Response choices were: improved, unchanged, or deteriorated function after coronary artery bypass grafting/percutaneous transluminal coronary angioplasty.

Results. Patients who had undergone coronary artery bypass grafting did not differ in subjective ratings on any measure from patients who had undergone percutaneous transluminal coronary angioplasty. There were no differences between spouses in the respective groups; spouse ratings also did not differ from patient ratings. Only in memory function did patients and spouses report a postprocedural decline.

Conclusions. No subjective differences were found in patients who had undergone either coronary artery bypass grafting or percutaneous transluminal coronary angioplasty. Spouse ratings agreed with each other and with patient ratings. Positive correlations were found between the questionnaire factors, suggesting that perceived health and well-being are associated with subjective cognition.


   Introduction
Top
 Abstract
 Introduction
Material and methods
 Results
 Comment
 Acknowledgments
 References
 
Cognitive sequelae after coronary artery bypass grafting (CABG) have been the focus of research interest for several decades. As a review study has shown [1], reported incidence of morbidity varies; incidence of in-hospital postoperative neuropsychological impairment as high as 79% has been cited. The discrepancy in results is very likely multifactorial and can be explained by heterogeneous definitions of cognitive decline and differences in neuropsychological test instruments, practice effects, testing intervals, surgical technique, and others.

The objective of the widespread research has been to determine the role of cardiopulmonary bypass in postoperative cognitive dysfunction. One review study concluded that postoperative neuropsychological deficits specific to cardiopulmonary bypass groups are attributable in part to perioperative embolization and other factors unique to the operation or cardiopulmonary bypass [2]. Lower baseline performance among patients with severe cardiac disease was also found, evidence of which has been corroborated elsewhere [3]. Keeping this in mind, the diagnostically similar cardiac patient groups undergoing CABG, valve procedures, or percutaneous coronary transluminal angioplasty (PTCA) were compared on neuropsychological measures. Results of the comparison showed that CABG and valve patients showed postoperative neuropsychological decline at discharge vis-à-vis PTCA patients. Nonetheless CABG and PTCA patients had comparable results after 5 years [4, 5]. These particular results suggest that CABG may give way to a higher incidence of short-term deficits. Although 18% to 29% of PTCA patients require revascularization within 1 year, PTCA is claimed to be a less costly and less invasive procedure [6]. Avoiding the potential central nervous system complications of cardiopulmonary bypass has spoken in favor of PTCA. In other surgical specialties, postoperative neuropsychological deterioration has been observed among abdominal, thoracic, orthopedic, and vascular groups [7, 8]. The mechanisms of the deterioration and the clinical relevance are, however, not yet fully understood.

In parallel several instruments and studies have been published regarding subjective perception of cognitive function after operation. In one instance 16% of patients rated 6 weeks after CABG that they sometimes or more often had cognitive difficulties according to the Cognitive Difficulties Scale [9]. Another instrument for self-assessment, the Cognitive Behavior Rating Scale, was used 2 to 3 years after CABG and valve procedures; the incidence of subjective complaints in specified cognitive domains was 2% to 14% (memory 11%) [10]. Shaw and co-workers [11] reported that 27% of patients had mild but not impeding cognitive symptoms 6 months after CABG; in comparison 38% reported cognitive impairment during the surgical hospital stay. Newman and colleagues [12] reported perceived memory decline in 27% of patients 1 year after CABG. Finally, Sotaniemi and associates [13] reported memory decline in 10 of 44 patients 5 years after valve replacement, although none of the patients found that this decrease in memory functioning affected activities of daily living. It was, however, concluded that postoperative cognitive decline was predictive of long-term cognitive functioning.

Among elderly noncardiac surgical patients, 17% of patients complained of residual cognitive symptoms 6 months after operation and of "not being the same as before surgery" [11]. Another report showed no preoperative test score differences among cardiac and vascular surgical patients on the self-assessed Cognitive Failures Questionnaire. After 2 months both groups reported significantly more cognitive failures than before operation [8].

As the cited studies show, a percentage of patients do report cognitive symptoms. Some patients even complain of being somehow different than before operation [7, 10]. Investigators have attempted to shed light on the significance of these reported symptoms. Poor cognitive functioning has been displayed to negatively affect perceived quality of life [14, 15]. The latter study showed that cognitive functioning before cardiac rehabilitation correlated to both quality of life before the intervention and to the degree of improvement after rehabilitation. Following this line of reasoning, relationships have been found between anxiety, depression, and reported cognitive dysfunction rather than between subjective and objective cognitive performance [9, 10, 12, 16]. In contrast one report found no relationship between depression levels and objective neuropsychological performance [16]. In sum, anxiety and depression can negatively affect perceived cognitive efficacy and, conversely, perceived cognitive functioning seemingly affects perceived quality of life.

To validate patient experience against other measures, we investigated subjective spousal experiences of patient quality of life after cardiac surgery [17]. Both patients and spouses reported improved quality of life 2 months and 1 year after operation. Agreement was highest on scales measuring physical health and physical functioning. Specific spouse perception of postoperative patient cognitive functioning was not assessed.

Consequently the study aimed to investigate subjective experiences of cognitive function, general health, and emotional state 1 to 2 years after CABG and PTCA, as perceived by 151 patients and their spouses.


   Material and methods
Top
 Abstract
 Introduction
 Material and methods
Results
 Comment
 Acknowledgments
 References
 
Subjects
Between September 16, 1997, and May 8, 1998, 273 patients underwent cardiac procedures at the Department of Cardiothoracic Surgery at the University Hospital in Malmö, Sweden, of which 212 had CABG as their sole procedure. Of these 212 patients, those participating in a concurrent study of postoperative neuropsychological function were excluded for the present study. The remaining 174 patients were investigated through the local census database for marital status and mortality. Starting with the most recent operation and going backward, the first 76 nondeceased, married patients were selected for inclusion.

Seventy-five married patients who had undergone PTCA with comparable mean age and date of procedure were selected as controls. Of the 151 selected couples, 37 patient couples (18 PTCA, 19 CABG) were excluded. Excluded patients did not differ in age from participating patients, but female subjects in the dropout group constituted 35% of the group compared to 17% in the patient group. Inability to participate occurred for the following reasons: medical reasons (3 patients), inclusion criteria were not met (3), PTCA followed by CABG (3), non-Swedish speaking (6), patient deceased (2), failure to contact patient (9), unwillingness to participate (6) and spouse inability (5 patients). Regarding PTCA followed by CABG, both patients with acute conversions and subsequent elective operation were excluded from the study. Demographic data for the remaining 114 patient couples are shown in Table 1.


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  		Table 1. Demographic Data of Participating Patients (CABG, n = 57; PTCA, n = 57)

 
Instruments
After approval from the local ethics committee (LU184-99; April 15, 1999), a questionnaire was constructed and revised, in two steps, after pilot interviews with nonstudy patients. Although perception of cognitive function was of primary interest, questions about memory and concentration were interspersed with questions about general health, social functioning, and emotional well-being. The interviewer, LH, explained to patients that the questionnaire’s objective was to inquire about patient and spousal perceptions of general health, social role functioning, and other changes that CABG or PTCA may have involved. Patients were instructed to answer questions by comparing their state of functioning just before operation or PTCA with functioning at the time of the interview. After modification, the final version of the questionnaire consisted of 47 questions covering five domains: perceived concentration (9 questions), perceived memory (7 questions), perceived general health (6 questions), perceived social functioning (2 questions), and perceived emotional state (17 questions). The objective was to cover a broad range of possible patient experience. All scales were intercorrelated. Internal reliability (Cronbach’s alpha) on the five original scales and the post-hoc depression scale ranged from 0.62 to 0.89. These are acceptable levels of internal consistency, that is, homogeneity, for an instrument of this type [18]. The majority of questions had the response options better/unchanged/worse, rated as 1/0/-1, respectively. Two questions were formulated as yes/no questions. The spouse questionnaire included exactly the same questions as the patient version.

Procedure
Patients and controls received a letter describing the study, after which a Master’s student in psychology (LH) contacted the patients per telephone to schedule an appointment with those patients and spouses willing and able to participate in the telephone interview. Each interview took 15 to 20 minutes. Spouses were interviewed first with patient interviews following immediately after. This procedure minimized the opportunity for couples to converse and thus influence the other’s responses.


   Results
Top
 Abstract
 Introduction
 Material and methods
 Results
Comment
 Acknowledgments
 References
 
There were no differences in demographic variables between patients who had undergone CABG or PTCA (Table 1). The hypothesis was that the two patient groups should differ on the psychological measures in this investigation. This was investigated in three ways. First, the patient groups were compared by means of t tests to discover any group differences in postprocedural psychological measures (Table 2). Second, the same comparisons were made using ratings from their spouses, thus comparing spouse ratings with patient ratings. Third, the spouse ratings of CABG and PTCA groups were compared. It was found that of the five scales none showed a significant difference between the groups on any of the analyses.


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  		Table 2. Comparison of CABG and PTCA Patients

 
One-sample t tests were used to determine whether patient scores differed from 0, that is, unchanged function after CABG/PTCA. The only scale in which patients perceived themselves as having deteriorated was memory (Table 3). Post-hoc analysis indicated a larger variance in the CABG group than in the PTCA group (Levene’s test) on the subscales memory (F = 3.58, p = 0.061) and social function (F = 3.74, p = 0.056).


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  		Table 3. CABG and PTCA Patients—One-Sample t Test

 
The results from the spouse ratings did not significantly discriminate between PTCA and CABG groups. As among patients, memory was the only scale in which spouses reported significant deterioration (Table 4). Spouses in both patient groups reported that patients had poorer postprocedural memory. A post-hoc variance analysis was replicated in the spouse group but yielded no significant results.


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  		Table 4. Spouses—One-Sample t Test

 
When comparing patient ratings with spouse ratings, a tendency toward greater variance among CABG patients than among their spouses (F = 3.25, p = 0.074) was found on the memory scale. No such difference was found with PTCA patients and their spouses.

Because no significant differences were found power must be considered. In the present study a moderate effect size (0.5 standard point) was expected. This power level suggests that in 75% of all studies significant results would be obtained. Given the obtained differences (post-hoc analysis) between the groups on the different subjective measures, between 200 to 4,000 patients in each group would be needed to reach a power level of 0.75. The objective of the study was to detect differences of clinical relevance for patients and spouses; the obtained differences were far from such levels.

Because depression has been reported to affect perception of cognitive performance, a post-hoc depression scale was constructed. Questions pertaining to mood were combined. Depression correlated not only with memory difficulties but also equally strongly with the original five scales of concentration, memory, social functioning, emotional state, and general health. Therefore, low ratings on any scale were associated with perceived poor functioning on all other scales.

The only significant correlation between demographic variables and perceived functioning was between education and the post-hoc category depression (r = 0.17, p < 0.05) for the entire sample. In the sample and patient/spouse groups, no correlations were found between the memory scale and age and education.


   Comment
Top
 Abstract
 Introduction
 Material and methods
 Results
 Comment
Acknowledgments
 References
 
No differences were found between CABG and PTCA patients, neither between patient and spouse ratings nor between spouse groups on any psychological measure. Therefore, bypass and angioplasty patients and their spouses rated patients similarly on scales assessing general health, memory, attention/concentration, emotional well-being, social functioning, and depression 1 to 2 years after intervention, a finding that renders the procedures comparable on these observed measures.

Patients with heart disease are generally known to have poorer neuropsychological test performance than age-matched controls [2, 3]. The presence and progress of atherosclerotic disease is generally assumed to be the root of the problem. Perhaps in this study a third noncardiac surgical group could have controlled for the effects of natural aging and general anesthesia on cognitive decline. One investigation has, for example, reported a reduction of two standard deviations from baseline values in as many as 10% of patients up to 2 years after noncardiac operations [19].

The only measure in which a significant change was found was the memory scale, and this decline was observed in both patient and spouse groups. Patients and spouses rated general health, social functioning, depression, and emotional well-being as unchanged compared to before the respective procedures.

Because the purpose of the investigation was to assess perceived change of function, absolute/relative levels of function were not studied. The questions were constructed to cover a fairly broad spectrum of memory and concentration. If differences between the groups do in fact exist, they must pertain to a specific aspect of cognitive functioning neglected in the questionnaire. Large differences in subjective experience between the groups could nonetheless be expected to surface in a study of this type.

Our instrument has not previously been validated. However, after surveying previously validated instruments we found none that specifically suited our objective: a retrospective judgment of cognitive function, emotional well-being, social functioning, and general health in comparison to pre-event (CABG or PTCA) functional level. Furthermore the available instruments were English or American; we found none that were translated and validated for a Swedish population.

Post-hoc analyses implied greater variance in the CABG group regarding memory and social functioning. Although the difference did not reach statistical significance, CABG patients and spouses had a higher level of education than did PTCA patients. There was no relationship between age, education, and perceived cognitive outcome in the present material. In agreement, in a follow-up of CABG patients neither age nor education was related to long-term neuropsychological outcome [19]. In general, patients with poorer memory also had poorer ratings on the other scales. Patients perceiving a decline in memory function did not differ from unchanged and improved groups on age and education. Thus, there was no evidence that postoperative memory decline was related to age or type of procedure.

A percentage of patients show long-term neuropsychological deficits after cardiopulmonary bypass [20, 21]. Different mechanisms of short- and long-term outcome have been suggested; it has been proposed that long-term outcome is more likely to be indicative of bypass-related deterioration. Using long-term incidence figures of less than 30% [21], this study should expect fewer than 34 of 114 patients to have deficits at the given time period. In the present study twice the expected number of patients, 34 of 57 CABG patients (59.6%), 36 of 57 PTCA patients (63.2%), 37 of 57 CABG spouses (64.9%), and 31 of 57 PTCA spouses (54.4%) reported that patient memory was inferior to preinterventional functioning. The discrepancy in this hypothetical comparison perhaps confirms the discrepancy between subjective and objective cognitive outcome described earlier.

The results suggest that both patients and spouses in the CABG/PTCA groups experienced significant deterioration in patient memory 1 to 2 years after operation or PTCA. Perceived cognitive dysfunction has been related to emotional factors and, therefore, it may be suggested that the positive correlations between the scales in the present study may partially be the result of the same phenomenon [18, 22]. Therefore, if one area of life is subjectively rated as poor, it follows that other areas also are perceived negatively.

On the measures of general health, emotional state, concentration, and depression, neither patients nor spouses in either group retrospectively reported postpreoperative differences. In contrast, prospective studies [18, 23] have reported postoperative improvement on quality of life measures among bypass patients at similar time points.

In sum, in the present data PTCA and CABG patients and their spouses rated memory as declined 1 to 2 years after treatment. Measures of attention, general health, social functioning, emotional state, and depression were unchanged. No differences were found between patient-patient, patient-spouse, or spouse-spouse in the CABG and PTCA groups.


   Acknowledgments
Top
 Abstract
 Introduction
 Material and methods
 Results
 Comment
 Acknowledgments
References
 
The study was funded by The National Association for Heart and Lung Patients, Stockholm, Sweden.


   References
Top
 Abstract
 Introduction
 Material and methods
 Results
 Comment
 Acknowledgments
 References
 

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  9. Khatri P., Babyak M., Clancy C., et al. Perception of cognitive function in older adults following coronary artery bypass surgery. Health Psychol 1999;18:301-306.[Medline]
  10. Kareken D.A., Williams J.M., Mutchnick M.G., Harter G., Torres I., George W.E. Self-report of cognitive function after cardiac surgery. Neuropsychol 1992;6:197-209.
  11. Shaw P., Bates D., Cartlidge N.E.F., et al. Long-term intellectual dysfunction following coronary artery bypass graft surgery. A six-month follow-up study. QJM 1987;62:259-268.[Abstract/Free Full Text]
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