New York Heart Association (NYHA) functional classification .... 2.60ââ. aEducation dummy-coded as greater than high school = 0 and high school or less = 1.
C 2005) Journal of Behavioral Medicine, Vol. 28, No. 5, October 2005 ( DOI: 10.1007/s10865-005-9010-y
Perceived Cognitive Function and Emotional Distress Following Coronary Artery Bypass Surgery Linda C. Gallo,1,4 Mary J. Malek,2 Alan D. Gilbertson,3 and Jeffrey L. Moore3 Accepted for publication: November 1, 2004; Published online: September 23, 2005
Many patients experience decrements in cognitive function and emotional adjustment following coronary artery bypass graft (CABG) surgery. Moreover, cognitive decline and emotional distress are often positively related. This study evaluated the cross-sectional and prospective associations of emotional and subjective cognitive complaints, to assess the hypothesis that they would be mutually reinforcing. Participants were 76 CABG patients recruited from Akron General Medical Center. Depression and anxiety symptoms and perceived cognitive difficulties were evaluated at a baseline postsurgical visit and re-assessed 5 months later. Emotional symptoms and perceived cognitive difficulties were significantly related both within and across time. After controlling for numerous potential confounds, baseline perceived cognitive difficulties predicted a more negative course of emotional symptoms during follow-up. Baseline emotional symptoms did not predict the course of perceived cognitive difficulties. Perceptions of cognitive decline may contribute to emotional distress in patients post-CABG. KEY WORDS: anxiety; cognitive function; coronary artery bypass surgery; depression .
and a significant proportion of CABG patients experience postsurgical alterations in their cognitive abilities (Borowicz et al., 1996; Haddock et al., 2003; van Dijk et al., 2000). Pooled findings from six studies suggest that about 23% of the patients experience cognitive decline following CABG (van Dijk et al., 2000). Typically these cognitive difficulties are transient and reversible (Selnes et al., 2003); however, for some patients, declines may persist for a year or even longer (McKhann et al., 1997; Newman et al., 2001). Additional research shows that CABG patients frequently experience anxiety and depression preand postoperatively (Andrew et al., 2000; Burker et al., 1995; Duits et al., 1999; Rymaszewska et al., 2003; Timberlake et al., 1996). Poor psychological adjustment following surgery can impede physical recovery, interfering with resumption of former activities (Carr and Powers, 1986; Dracup et al., 1984; Soderman et al., 2003), leading to more persistent symptoms (Borowicz et al., 2002; Perski et al., 1998), and increasing the likelihood of recurrent coronary events, hospitalizations, or mortality (Blumenthal et al., 2003; Burg et al., 2003; Connerney et al., 2001;
Coronary artery bypass graft (CABG) surgery is a well-established and widely used procedure for treating coronary artery disease (CAD) with severe angina pectoris (Califf et al., 1996). Recent statistics from the American Heart Association (2001) indicate that approximately 51,600 CABG surgeries are performed annually. CABG frequently results in substantial alleviation of angina symptoms, yet it may also impair quality of life by adversely impacting other areas of functioning, including emotional well-being and cognition. Prior research has demonstrated that aspects of the CABG procedure have a direct effect on cognitive functioning (Newman, 1996; Selnes et al., 1999) 1 SDSU/UCSD
Joint Doctoral Program in Clinical Psychology, San Diego State University, San Diego California. 2 Wellspring Counseling Center, Akron, Ohio. 3 Department of Psychiatry & Behavioral Sciences, Akron General Medical Center, Akron, Ohio. 4 To whom correspondence should be addressed at SDSU/UCSD Joint Doctoral Program in Clinical Psychology, 6363 Alvarado Court, Suite 103, San Diego CA 92120; e-mail: lcgallo@sciences. sdsu.edu.
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434 Scheier et al., 1999; Sullivan et al., 2003; for review, see Pignay-Demaria et al., 2003). Importantly, previous research suggests that patients high in “neuroticism” (Chandarana et al., 1988; Ramshaw and Stanley, 1984), or depression and anxiety (Khatri et al., 1999; Vingerhoets et al., 1995), often perceive cognitive declines in excess of those that are observed on objective tests. The converse association might also be important. That is, CABG patients who perceive that they are having greater cognitive difficulties could experience higher levels and a more persistent course of emotional distress. This assertion is consistent with research showing that individuals who perceive their health as poor are generally more depressed than those who perceive their health as good (Taylor and Aspinwall, 1990; see, Duits et al., 2002, for a recent report of this association in CABG patients). Individuals who are depressed may magnify the existence of cognitive problems by attending to negative events and disregarding positive occurrences, fostering further escalation of distress and perceptions of cognitive problems. Thus, perceived cognitive difficulties and emotional distress could be associated in a dynamic manner, so that each influences and maintains the other (c.f., Khatri et al., 1999). If borne out, this cyclic relationship would have important implications for psychosocial interventions in CABG patients. However, to our knowledge, the effects of perceived cognitive impairment on the course of emotional distress has not been tested. The current study examined emotional symptoms and perceived cognitive functioning on two occasions following CABG surgery. Thus, we examined (1) the effects of perceived cognitive difficulties at the first time point on the course of depression and anxiety and (2) the effects of emotional symptoms at the first time point on the course of perceived cognitive functioning. We hypothesized that perceived cognitive difficulties and emotional distress would be positively associated at an initial postsurgical visit and at a 5-month follow-up visit. We further hypothesized that patients perceiving more cognitive difficulties at the first visit would experience a more persistent course of emotional symptoms and that the converse prospective association would also be observed. METHOD Participants and Recruitment Patients presenting to the offices of cardiothoracic surgeons at Akron General Medical Center
Gallo, Malek, Gilbertson, and Moore for a CABG surgery follow-up visit were the identified patient population. Between September and December 2000, 101 of the 355 patients presenting to the surgeons’ offices for post-bypass follow-up were approached regarding participation. Research staff did not approach the remaining patients for a variety of reasons including investigators’ time constraints, scheduling conflicts, surgeons’ schedule changes due to emergency, and patient appointment changes. One patient who was currently involved in psychotherapy was excluded from the sample, because a supportive intervention was originally planned for patients reporting concern about cognitive difficulties. The intervention component was dropped from the protocol due to staffing issues. Five patients who had previously undergone CABG, experienced a myocardial infarction, or who were scheduled for another procedure in addition to CABG were excluded from the study, so that we could evaluate the hypothesized associations in a group of patients with similar illness severity. Fourteen of the patients approached refused participation (i.e., 85% participation rate); they included 8 males (mean age = 71.88 years) and 6 females (mean age = 61.67 years). Five patients (all White males) did not complete the follow-up assessment. Of the patients who did not complete follow-up, one was deceased, two did not respond to the request for a follow-up interview, and two did not complete the relevant self-report measures. These eliminations, refusals, and incomplete files resulted in a final sample of 76.
Procedure The initial assessment took place at patients’ first (n = 60) or second (n = 16) postsurgical visit. On average, patients were seen 41.81 days (SD = 21.83) following surgery. After providing informed consent, participants completed the baseline evaluation. All questions and instruments were administered verbally, and participants were given a written copy of the measures if needed to facilitate their understanding. The evaluation included questions about sociodemographic characteristics and self-report assessments of depression, anxiety, and perceived cognitive difficulties. We intended for all patients to receive follow-up evaluations for 4–5 months postenrollment assessment, but due to scheduling problems and difficulty reaching patients, the follow-up period ranged from 3.5 to 7.5 months (M = 146.45 days, SD = 22.40). Patients were sent a letter informing
Emotional Distress and Perceived Cognition them of the upcoming telephonic interview 7–10 days before the follow-up date. Participants unable or unwilling to complete the evaluation telephonically were mailed questionnaire packets. The follow-up evaluation included the self-report measures of depression, anxiety, and perceived cognitive difficulties. Participants reporting clinically significant depression at either evaluation were offered assessment and treatment at the Akron General Medical Center’s Psychiatry Residents’ Clinic, or they were provided with an appropriate community referral. All evaluations were performed by the first author, or by two trained members of the research staff. The first author conducted quality control meetings at several points during the study to maintain consistency in procedures. Assessment Instruments Depression Depression symptoms were assessed using the Center for Epidemiological Studies Depression Scale (CES-D; Radloff, 1997), a 20-item self-report inventory designed for use with nonpsychiatric populations. Patients were asked to describe the severity of depressive symptoms, such as “I had crying spells” and “I thought my life had been a failure,” since their surgery (at enrollment) and since enrollment (at follow-up). Previous research shows that the CES-D is reliable and valid for use in medical populations and that scores are not unduly influenced by physical health problems (Hann et al., 1999). CES-D scores range from 0 to 60, with higher scores indicating greater depressive symptoms. Scores higher than 16 are typically considered indicative of clinically significant depression. The internal consistency for the CES-D in the current sample was estimated at α = 0.88 and α = 0.84, for the first and second evaluations, respectively.
435 symptoms since their surgery (at enrollment) and since enrollment (at follow-up). Scores range from 20 to 80, with higher scores indicating greater anxiety. Spielberger (1983) suggested a cut score of 44 to indicate clinically significant anxiety. The internal consistency estimates for the STAI for the current sample were α = 0.91 and α = 0.93, for the first and second evaluations, respectively. Perceived Cognitive Difficulties The Cognitive Difficulties Scale (CDS; McNair and Kahn, 1983) is a self-report measure of perceived problems with short- and long-term memory, concentration, attention, and psychomotor functioning. Respondents indicate the frequency with which 39 “everyday inefficiencies, lapses of attention or memory, and related functions,” have occurred on a 5-point Likert scale ranging from “not at all” to “very often” (e.g., “I have trouble recalling frequently used phone numbers”). The total scale score ranges from 0 to 156, with higher scores indicating greater perceived cognitive difficulties. Prior research suggests a small association between subjective appraisals and objective measures of cognitive function in CABG patients (Khatri et al., 1999; Newman et al., 1989). Furthermore, a previous study that administered the CDS to more than 1600 participants found that scores on the scale correlated only weakly with scores on objective measures of memory and attention (Derouesne et al., 1993). Hence, this scale is best viewed as an assessment of subjective rather than objective cognitive difficulties. The time frame for assessment of perceived cognitive difficulties was consistent with that for depression and anxiety. Cronbach’s internal consistency for the current sample was estimated at α = 0.94 and α = 0.96, for the first and second evaluations, respectively. Sociodemographic Information
Anxiety The Spielberger State-Trait Anxiety Inventory (STAI; Spielberger et al., 1977) was used to assess anxiety symptoms. This widely used scale is highly reliable and valid (Spielberger et al., 1999). The scale consists of 20 feeling statements for which respondents indicated how frequently they experienced the particular symptom, on a 4-point Likert scale. Representative items include “I feel nervous” and “I feel worried.” Consistent with the modified instructions for the CESD, patients were asked to describe their
Information regarding patients’ age, sex, race/ethnicity, marital status, and educational attainment was collected from charts, or during the enrollment interview as needed. Medical Information Surgical Variables Variables that could affect postsurgical cognitive function were extracted from chart
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review—specifically, cardiopulmonary bypass (onpump) procedures (Van Dijk et al., 2002), and the number of bypass grafts (Hammeke and Hastings, 1988; Newman, 1995). It has been speculated that a slight lowering of body temperature may protect the patient from cerebral damage while on bypass (McLean et al., 1994). Therefore, we also extracted data concerning patients’ body temperature during surgery.
ter both physically and psychologically. Several of the most serious and predictive complications from a large number of possible complications were collected from patient charts for this study, including myocardial infarction, atrial fibrillation, stroke, infection, and postoperative bleeding. RESULTS Participant Characteristics
Comorbid Medical Conditions The presence of comorbid medical conditions that could affect patients’ cognitive function, including hypertension, chronic obstructive pulmonary disease, peripheral vascular disease, chronic renal failure, diabetes mellitus, hypercholesterolemia, and CAD, was assessed by participant report and verified through chart review during the course of the initial evaluation. Medical information not obtained during the initial contact with participants was gathered from medical charts by trained research staff.
Of the 76 participants who completed both the assessments, 52 (78.4%) were male, 74 (97.4%) were White, and 54 (71%) were married or living with a partner. The majority of the sample (49, 64.5%) had a high-school education or less, 16 (21%) had completed technical school or some college, and 11 (14.5%) had a 4-year college degree. On the average, participants were 64.32 years old (SD = 10.79). Participants who completed both of the assessments did not differ from those who completed the baseline only in terms of age, depression, anxiety, or cognitive difficulties reported at baseline (all p-values > 0.15).
Illness Severity Overall disease severity was assessed via the New York Heart Association (NYHA) functional classification, assessed prior to surgery. The NYHA scale quantifies impairment due to cardiac disease, according to the following: I (no physical limitations); II (slight limitation); III (marked limitation); and IV (complete limitation). Surgical Complications Patients having fewer postoperative complications typically recover more fully and function bet-
Bivariate Associations Between Emotional Distress and Perceived Cognitive Function Table I shows the Pearson Product Moment correlations among the measures of depression, anxiety, and perceived cognitive function, as well as descriptive statistics for these variables, for both assessment points. Twenty-three (30.3%) patients had CES-D scores in the “clinically depressed” range at Time 1 and 7 (9.2%) patients had scores in the “depressed” range at Time 2. Seventeen (22.4%) and 7 (9.2%) patients had clinically significant STAI scores at Time 1 and Time 2, respectively. On average, emotional
Table I. Bivariate Correlations and Descriptive Statistics for the Measures of Depression, Anxiety, and Perceived Cognitive Difficulties, at the Time 1 and Time 2 Evaluations Time 1
1 2 3 4 5 6
Time 2
CES-D
STAI
CDS
CES-D
24.93 (9.61) .57∗∗ .47∗∗ .53∗∗ .52∗∗ .38∗∗
33.41 (10.73) .52∗∗ .50∗∗ .51∗∗ .33∗∗
24.93 (18.85) .48∗∗ .57∗∗ .54∗∗
7.71 (7.47) .76∗∗ .52∗∗
STAI
28.17 (9.78) .73∗∗
Note. Means and standard deviations (in parentheses) are shown on the diagonal. ∗∗ Correlation is significant at p < 0.01.
CDS
25.40 (21.10)
Emotional Distress and Perceived Cognition
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Table II. Hierarchical Multiple Regression Analysis Predicting Changes in Depression from Sociodemographic Factors, Time Between Assessments, Surgical Variables, Time 1 Depression, and Time 1 Perceived Cognitive Difficulties Variable lessa
High school or Not married or cohabitatingb Female gender African-American race/ethnicity Age (years) Time between assessments (days) Neurologic complications Perfusion time (min) Cross clamp time Time 1 depression Time 1 perceived cognitive difficulties
B
SE
β
−1.06 2.64 3.11 −3.20 −0.13 −0.05 3.32 0.06 −0.06 −0.71 0.11
1.59 1.65 1.82 4.51 0.08 0.03 3.66 0.04 0.05 0.09 0.04
−0.06 0.14 0.17 −0.06 −0.17 −0.13 0.08 0.29 −0.20 −0.81 0.25
t (1,62) −0.67 1.60 1.71# −0.71 −1.67# −1.50 0.91 1.69# −1.17 −7.82∗∗∗ 2.60∗∗
dummy-coded as greater than high school = 0 and high school or less = 1. status entered as a single dummy-code, with married or cohabitating = 0 and divorced, widowed, and single = 1. # p ≤ 0.10; ∗∗ p < 0.01; ∗∗∗ p ≤ 0.001. a Education b Marital
distress tended to decrease over time, and participants showed little change in perceived cognitive functioning. Emotional distress and perceived cognitive difficulties were significantly positively correlated, within and across time. Does Perceived Cognitive Function Predict the Level and Course of Emotional Distress? The hypothesis that higher perceived cognitive difficulties at the initial evaluation would predict a more persistent course of emotional symptoms was tested in two hierarchical multiple regression analyses. Change in depression and change in anxiety, calculated as Time 2 − Time 1 score so that higher values indicate more persistent symptoms, were the dependent variables in these analyses. Predictors were entered in the following order: (1) sociodemographic factors (i.e., education, ethnicity, age, marital status, and sex) and days between assessments; (2) surgical variables (i.e., time on bypass, type of bypass, lowest bladder temperature, and number of bypass grafts); (3) Time 1 depression or anxiety; and (4) Time 1 perceived cognitive difficulties score. Depression In the analysis examining depression change, only block 3, Time 1 depression, R2 = 0.37, F(1, 65) = 52.34, p < 0.001, and block 4, Time 1 perceived cognitive difficulties, R2 = 0.04, F(1, 64) = 6.74, p < 0.05, were statistically significant. The total model explained 59% of the variance in depression
change, F(11, 64) = 8.34, p < 0.0001. The coefficients for each predictor at the final model step, which reflect the effect for each variable controlling for all other predictors, are shown in Table II. As hypothesized, higher levels of perceived cognitive difficulties at enrollment predicted a more persistent depression course during recovery. In a secondary analysis that controlled for comorbid major medical conditions and functional status, perceived cognitive difficulties remained a significant independent predictor of depression course, t(1, 61) = 2.85, β = 0.25, p < 0.01. NYHA class was not included in medical records for 10 participants and, therefore, the sample size for this analysis was 66. Anxiety Consistent with the analysis for depression, only block 3, Time 1 anxiety, R2 = 0.38, F(1, 65) = 50.38, p < 0.001, and block 4, Time 1 perceived cognitive difficulties, R2 = 0.10, F(1, 64) = 16.91, p < 0.001, predicted significant variance in the outcome after controlling for previous blocks. The total model explained 62% of the variance in change in anxiety, F(11, 64) = 9.36, p < 0.0001. The coefficients for the final model and their statistical tests are shown in Table III. As hypothesized, higher levels of perceived cognitive difficulties at enrollment predicted a more persistent course of anxiety during recovery from CABG. Consistent with the results for depression, perceived cognitive difficulties remained a significant independent predictor of change in anxiety in a secondary analysis that controlled for the presence of comorbid major medical
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Gallo, Malek, Gilbertson, and Moore Table III. Hierarchical Multiple Regression Analysis Predicting Changes in Anxiety from Sociodemographic Factors, Time Between Assessments, Surgical Variables, Time 1 Anxiety and Time 1 Perceived Cognitive Difficulties Variable lessa
High school or Not married or cohabitatingb Female gender African-American race/ethnicity Age (years) Time between assessments (days) Neurologic complications Perfusion time (min) Cross clamp time Time 1 anxiety Time 1 perceived cognitive difficulties
B
SE
β
0.27 2.38 4.92 −11.77 −0.31 −0.06 2.56 0.02 −0.03 −0.81 0.21
1.85 1.89 2.08 5.22 0.09 0.04 4.23 0.04 0.06 0.09 0.05
0.01 0.11 0.23 −0.19 −0.33 −0.14 0.05 0.08 −0.10 −0.85 0.38
t (1,62) 0.15 1.26 2.37∗ −2.26∗ −3.61∗∗∗ −1.65# 0.60 0.47 −0.62 −8.90∗∗∗ 4.11∗∗∗
dummy-coded as greater than high school = 0 and high school or less = 1. status entered as a single dummy-code, with married or cohabitating = 0 and divorced, widowed, and single = 1. ∗ p < 0.05; ∗∗∗ p ≤ 0.001; # p ≤ 0.10. a Education b Marital
conditions and CAD severity, t(1,61) = 2.85, β = 0.25, p < 0.01. Does Emotional Distress Predict the Course of Perceived Cognitive Function? Two additional hierarchical multiple regression analyses tested the hypothesis that higher levels of emotional distress at the initial evaluation would predict a more persistent course of perceived cognitive difficulties during recovery from CABG. The dependent variable was change in perceived cognitive difficulties, calculated as Time 2 − Time 1 score, so that higher values indicate persistence of perceived difficulties. Predictors were (1) sociodemographic factors and days between assessments; (2) surgical variables; (3) Time 1 perceived cognitive difficulties; and (4) Time 1 depression or anxiety. One participant failed to complete the follow-up cognitive difficulties measure, and these analyses are therefore based on the results obtained from 75 participants. Depression The total model accounted for 35% of the variance in change in perceived cognitive difficulties, F(11, 63) = 3.02, p < 0.01. Age, β = −0.35, t(1, 61) = −2.80, p < 0.01, and Time 1 cognitive difficulties, β = −0.48, t(1,61) = −4.00, p < 0.001, were the only statistically significant independent predictors at the final model step. Thus, contrary to predictions, depression symptoms at Time 1 did not predict the persistence of perceived cognitive difficulties.
Anxiety The model regressing change in perceived cognitive difficulties on Time 1 anxiety accounted for 34% of the variance in the outcome, F(11, 63) = 2.97, p < 0.01. Consistent with the analysis for depression, age, β = −0.39, t(1, 61) = −3.23, p < 0.01, and Time 1 perceived cognitive difficulties, β = −0.44, t(1, 61) = −3.58, p < 0.001, were the only statistically significant independent predictors. Thus, anxiety symptoms at Time 1 did not predict the persistence of perceived cognitive difficulties.
DISCUSSION Prior studies have identified an association between CABG patients’ emotional distress and their perception of cognitive difficulties (Derouesne et al., 1999; Jorm et al., 1997; Khatri et al., 1999; Newman et al., 1989, 1990). In part, this relationship may reflect the true influence of mood states on cognitive function, such as attention and verbal memory (Cassens et al., 1990). A negative information processing bias, leading to distorted perceptions of cognitive difficulties in emotionally distressed individuals (Khatri et al., 1999; Newman et al., 1989; Smith et al., 1994), could also contribute to this relationship, and could foster further emotional distress. The current study tested this hypothesis, and examined whether emotional distress and perceived cognitive difficulties would be mutually reinforcing over time. Consistent with this hypothesis, we found that emotional symptoms and perceived cognitive
Emotional Distress and Perceived Cognition difficulties were significantly associated, both within and across time. However, only one component of our hypothesis concerning changes in emotional symptoms and perceived cognitive function was supported. Specifically, we found that perceived cognitive difficulties soon after bypass surgery predicted a more negative course of anxiety and depression symptomatology during the 5 months of follow-up. Perceived cognitive difficulties at the earlier time point accounted for 4% of the variance in depression symptom changes, and 10% of the variance in anxiety symptom changes, after controlling for baseline emotional distress and sociodemographic and medical covariates. In contrast, emotional distress shortly after surgery did not significantly predict changes in perceived cognitive difficulties. Hence, our study does not provide evidence for the existence of a reciprocal association between the constructs—a possibility advanced by Khatri and colleagues (1999). On the other hand, the fact that only one of the hypothesized prospective associations was identified minimizes the possibility that emotional distress and perceived cognitive difficulties simply represent redundant indicators of a common underlying construct. The finding that perceptions of cognitive dysfunction lead to increased emotional distress is consistent with research showing the relationship between self-perceived health problems and depression (Taylor and Aspinwall, 1996). CABG patients who interpret transient cognitive dysfunction as a serious health-related problem or permanent deficit may suffer greater emotional distress than their counterparts who make a more benign interpretation of cognitive difficulties. Supporting this assertion, research has shown that CABG patients who experience negative emotions (i.e., depression, anxiety) not only report more symptoms but also assign more serious meaning to their symptoms (Perski et al., 1999; Strauss et al., 1992). These individuals may then be at higher risk for further decline in mood, and a subsequent downward spiral of negative mood, physical complaints, and perceived symptoms. The ultimate result of this cycle may be significant psychiatric or social problems. Furthermore, given prior research showing that emotional distress predicts multiple aspects of recovery in CABG patients (Borowicz et al., 2002; Burg et al., 2003; Carr and Powers, 1986), deleterious physical health effects may ensue. Consistent with prior research (Andrew et al., 2000; L´ındal et al., 1996), we found relatively high depression and anxiety symptoms postoperatively.
439 In fact, 30 and 22% of patients reported clinically significant levels of depression and anxiety, respectively, at the first postsurgical visit. Depression and anxiety typically remitted substantially during follow-up, although 9% of the patients still had clinically significant depression, anxiety, or both (n = 4). Notably, the significant relationship between depressive and anxiety symptoms is consistent with prior research in CABG patients (Duits et al., 1999) and in many other samples (Clark and Watson, 1991). This association supports the existence of an underlying generalized negative affect construct (Watson et al., 1995a,b), which may be affected by perceptions of cognitive problems. Overall, the results suggest that perceptions of cognitive difficulties in particular warrant attention by health care providers, as an indicator of patients’ emotional well-being and subsequent health risks, as noted by others (e.g., Vingerhoets, 1998). Anxiety and depression subsequent to CABG surgery may be reduced by attending to patients’ perceptions of and concerns about their cognitive abilities both preand postoperatively. Practitioners might consider including a screen of patients’ perceived cognitive difficulties following CABG, and addressing patient concerns as indicated. Prior studies have documented that well-designed education interventions for surgery patients can prevent many postoperative complications and adjustment problems (Anderson, 1987; Mahler and Kulik, 1998), and a similar effect was observed anecdotally in the current research. Specifically, patients reported that the information provided by surgeons played an important role in decreasing their concerns about cognitive problems and mood disturbances. The findings of the current study must be interpreted in light of several methodological limitations. First, the patient sample is relatively small, and was not randomly selected. Further, consistent with the demographics of the community, the sample was nearly exclusively White. We were also unable to approach all patients in the eligible population for participation. This latter issue is unlikely to have biased the sample, given that when patients were not screened, this typically reflected scheduling conflicts on the part of the investigators. The effect is, therefore, likely to be random. On the other hand, the high participation rate (86%) of eligible patients who were approached should be noted as a strength of the current study. Replication of these results in larger, randomly selected, and ethnically diverse samples is recommended.
440 The fact that we used modified instruction sets for the self-report instruments (i.e., since surgery, since follow-up, rather than in the past week (i.e., typical instruction set for the CES-D)) could also represent a limitation of the current study, in terms of affecting the validity or reliability of the measures. We altered the wording of the instructions in an attempt to make the instruments more applicable to patients’ experiences surrounding their surgery, and so that both emotional symptoms and perceived cognitive difficulties would be assessed within the same time frame. However, prior research suggests that retrospective self-reports are often influenced by temporally recent events and mood fluctuations (Eisenhower et al., 1991), suggesting that the reports probably reflect emotional symptoms and perceived cognitive difficulties at the time of the assessment. Furthermore, the observance of strong internal consistency estimates for all measures, the fact that all scales targeted the same timeframe, that findings were theoretically consistent, and that only one of the two predicted temporal associations were observed lends confidence in the identified findings. We did not administer cognitive tests and, therefore, cannot evaluate the relative contribution of objective versus subjective cognitive difficulties to mood symptoms. However, a prior study showed that scores on the CDS were only weakly correlated with objective measures of cognitive functioning (Derouesne et al., 1993), suggesting that the current results can be attributed primarily to subjective perceptions. Assessing both emotional well-being and perceived cognitive difficulties at two assessment points is a strength of the current research. On the other hand, given that previous research suggests that presurgical levels of emotional distress (Duits et al., 1999) and cognitive dysfunction (Millar et al., 2001) are strongly predictive of postsurgical levels of these variables, it would have been preferable to perform a presurgical assessment. A final issue is that the current study did not include a control group. Despite these limitations, the current study provides initial evidence that perceived cognitive difficulties may be important to consider in efforts to predict and treat emotional distress in CABG patients. Future research is recommended to continue to explore this hypothesis, preferably in studies that incorporate multiple pre- and postsurgical assessments of cognitive function (both objective and subjective) and emotional distress. In a review of the psychiatric and social consequences of CABG surgery, Mayou (1986) noted
Gallo, Malek, Gilbertson, and Moore the difficulty in identifying which CABG patients are at risk for psychosocial problems. Identification of a measurable construct that is predictive of postoperative psychological adjustment would be an important contribution to the care and management of CABG patients. The current study indicates that perceived cognitive difficulties are quite valid for consideration in this regard.
ACKNOWLEDGMENTS Thanks are due to George Litman, M.D., Cardiology Service Chief, Akron General Medical Center, NEOUCOM, and Robert Kamienski, M.D., Cardiovascular Surgery Service Chief, Akron General Medical Center, NEOUCOM for their support of this project. In addition, we thank Laura Whitaker, Susan Kerns, and Manzoor Elahi for assistance with data collection and Ana Maria Vranceanu for assistance with data entry and validation. The first author was supported by NIMH grant MH6610101 during preparation if this manuscript.
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