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J Thorac Cardiovasc Surg 2000;120:505-512
© 2000 The American Association for Thoracic Surgery
Surgery for Acquired Cardiovascular Disease |
From the Departments of Anaesthesiology,a Cardiac Surgery,b and Psychiatry,c Ludwig-Maximilians University, Munich, Germany.
This study was supported by a grant from Hoffman-La Roche, GrenzachWyhlen, the Lilly Foundation, and the Techniker Krankenkasse, all in Germany.
Address for reprints: Christian Stoll, MD, Department of Anaesthesiology, Klinikum Grosshadern, LudwigMaximilians University, 81377 Munich, Germany (E-mail: christian.stoll{at}ana.med.uni-muenchen.de ).
| Abstract |
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| Introduction |
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Severe cardiac disease like myocardial infarction or the symptoms of angina pectoris are often perceived by the individual as a life-threatening and devastating event. The knowledge of the need for the imminent operation contributes to the perceived physical and psychologic stress. Anesthesia, surgery, and cardiopulmonary bypass are strong physical and emotional stressors, and psychologic or neurologic alterations are often observed in patients after cardiac surgery.
8 After the operation, the patients are transferred to the intensive care unit (ICU), where they are subjected to weaning from mechanical ventilation, early extubation, and mobilization. High-technology intensive care has an important role in the improvement in mortality and morbidity in this field. However, along with the severe underlying disease process, that same ICU environment can confer extreme physical and mental stress; anxiety, pain, respiratory distress, and nightmares are often reported after ICU treatment.
6 Whether the prolonged exposure to these combined stressors results in long-lasting negative effects on emotional well-being, mental health, or HRQL is currently unknown.
Post-traumatic stress disorder (PTSD) is the development of characteristic symptoms after exposure to extreme stress. Events that trigger PTSD involve experiencing a serious threat to one's own physical integrity that is accompanied by intense fear, horror, and helplessness.
9 Diagnostic criteria for PTSD include a history of exposure to one or more traumatic events and symptoms from each of 3 symptom clusters: intrusive recollections, avoidance/numbing symptoms, and hyperarousal symptoms
10 (Table I). Patients with PTSD showed significant impairments in psychosocial functioning in a recent study in survivors of ICU treatment,
6 and PTSD has been described in patients after cardiac events.
11
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| Methods |
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Eligible patients were identified by means of a computerized documentation system that provided the following data: type of surgical procedure (AVR or CABG), all necessary data to calculate the preoperative Clinical Severity Score for Coronary Artery Disease (CSS) according to Higgins and associates,
12 and the Simplified Acute Physiology Score (SAPS II)
13 on admission to the ICU, duration of mechanical ventilation and ICU treatment, and 30 day survival/nonsurvival.
The study was approved by the local institutional review board and data protection met the standard set by German law. Eligible patients were initially contacted by telephone and received a detailed explanation of the purpose of the study. A standard text was used for this initial approach and, after informed oral consent, the patients were mailed questionnaires assessing HRQL, the incidence and intensity of PTSD, and patient satisfaction.
HRQL
HRQL was measured with the self-administered Medical Outcomes Study Short Form Survey that consists of 36 questions (SF-36) and covers 8 basic health concepts: physical function, social function, physical role function, emotional role function, mental health, pain, vitality, and general health perception.
14 The measurement model underlying the construction of the SF-36 scales includes items and 8 scales that aggregate 2 to 10 items each. All but 1 of the 36 items are used to score the 8 SF-36*
scales.
15 In addition, summary scores for physical and mental health can be calculated.
16 A score ranging from 0 to 100 is calculated for the 8 scales, with higher scores indicating a better HRQL. Published reliability statistics of the SF-36 have exceeded 0.80 in most studies (a minimum standard of 0.70 is recommended for measures used in group comparisons).
6,15 Clinical studies have shown that the physical scales of the SF-36 (physical functioning, role-physical, and bodily pain) tend to be responsive to the benefits of heart valve surgery.
17 Likewise, the mental health scales (mental health, role-emotional, social functioning, and vitality) have been shown to be responsive in comparison with patients with and without PTSD.
6 The SF-36 has been validated in patients after ICU treatment,
18 and a recent study has demonstrated that differences in angina severity as measured by the Canadian Cardiovascular Society Classification were related to subscales of the SF-36.
19 A psychometrically validated German translation of the SF-36 was used in patients having cardiac surgery and in control subjects.
4
Control groups for HRQL measurements
For the purpose of this study, we generated 4 different control groups that were identical to the cardiac surgical patients under study with regard to number, age, sex, and home country (West Germany). Control subjects were selected from a large database (n = 3000) used to provide standard values for the SF-36 in a German population. HRQL control group 1 represented age- and sex-identical healthy subjects (defined as healthy, age- and sex-identical individuals without evidence of cardiovascular disease, diabetes, hypertension, or cancer). Control group 2 consisted of medically treated patients with a recent myocardial infarction (<1 year), HRQL control group 3 represented individuals with medically treated chronic stable angina, and HRQL control group 4 consisted of patients with a moderate degree of heart failure (New York Heart Association class IIIII). These 4 control groups were generated to simplify the interpretation of results and to allow a comparison of HRQL between patients who have had cardiac surgery, normal subjects, and patients with chronic, medically treated cardiovascular diseases.
PTSD
PTSD was measured by means of a modified German version of the Post-Traumatic Stress Syndrome 10-Questions Inventory (PTSS-10), a self-report scale originally based on the Diagnostic and Statistical Manual Criteria (DSM), third edition, criteria of The American Psychiatric Association for PTSD. The instrument was originally introduced as a screening test to determine PTSD cases in the aftermath of a disaster and in victims of torture.
20 This questionnaire records the presence and intensity of 10 post-traumatic stress symptoms: sleep disturbance, nightmares, depression, hyperalertness, withdrawal (emotional numbing and inability to care for others), generalized irritability, frequent changes in mood, guilt, avoidance of activities prompting recall of possible traumatizing events, and increased muscle tensions. When completing the questionnaire, the patients rate their symptoms on a scale from 1 (never) to 7 (always), and a sum score ranging from 10 to 70 points is calculated.
The questionnaire has been validated in patients with PTSD after prolonged ICU treatment by means of a doubleblind interview technique performed by psychiatrists. These investigations found an optimal cutoff score of 35 points of the questionnaire for diagnosis of PTSD. The sensitivity of the instrument at this threshold value was 0.77 (95% confidence interval 0.54-1.0), specificity was 0.97 (95% confidence interval 0.91-1.00), positive predictive value was 0.91 (95% confidence interval 0.74-1.00), negative predictive value was 0.93 (95% confidence interval 0.85-1.00), and accuracy was 0.92.
21
Comparison groups for PTSD measurements
Individuals from PTSD comparison groups completed the same PTSD questionnaire as the cardiac surgical group. PTSD comparison group I (n = 80) represented patients after major maxillofacial surgery. This group contained patients treated for tumors and was selected because it represents sick hospitalized patients who require perioperative intubation and mechanical ventilation but almost never experience ICU treatment and should therefore have a lower total stress exposure. PTSD comparison group II (n = 80) consisted of healthy individuals without known acute or chronic diseases. For reasons of sample composition, individuals from both PTSD comparison groups were generally younger than the cardiac surgical patients under study. Unlike HRQL controls, patients and the comparison group in the PTSD part of this study were therefore only age and sex comparable but not identical.
Patient satisfaction
Patient satisfaction with 20 different aspects of daily life (ranging from satisfaction with health status to life in general, see Table II for item definitions), including contentment with surgical treatment, was evaluated with the aid of a specially designed questionnaire. When completing this instrument, the patients rate their degree of satisfaction with each item on a scale from 0 (no satisfaction at all) to 10 (maximal satisfaction); in addition, a sum score ranging from 0 to 200 can be calculated.
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2 test. We performed stepwise regression analyses to determine those patient or treatment variables that best explained variations in PTSD and SF-36 HRQL scores.
Backward elimination was used to be able to include all variables that were collected because we believed them to be important explanatory variables. Unimportant variables were then removed until all remaining variables contributed significantly.
22 Results are expressed as medians and ranges or proportions, as appropriate. All statistical calculations were performed with the SPSS statistical package (SPSS Inc, Chicago, Ill).
| Results |
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When patients after cardiac surgery were compared with age- and sex-identical healthy controls (HRQL control group 4), differences emerged both in the physical and mental domains of the SF-36. Patients after cardiac surgery reported somewhat lower values regarding summary scores of physical function (difference of median values between patients after cardiac surgery and healthy controls: 7.90, P < .05) and mental health (difference of median values: 6.40, P < .05, Table IV). There was, however, no significant difference between perception of general health (differences of medians: 10, P > .05) and the prevalence and intensity of chronic pain (differences of medians: 16,*
P > .05) between patients after cardiac surgery and healthy controls. However, index patients described significantly better physical function than patients after a recent myocardial infarction (difference of median values between patients after cardiac surgery and after myocardial infarction: 6.01, P < .05). Chronic pain was significantly more common in patients after a recent myocardial infarction (differences of medians: 27, P < .05). Patients after cardiac surgery had significantly higher mental health and vitality scores than patients after a recent myocardial infarction (differences of medians: 18 and 17.5, respectively, P < .05). Index patients had a significantly higher general health perception than all controls with the exception of healthy subjects but showed significantly lower scores for emotional role function than all control groups. Table IV
compares SF-36 data between patients after cardiac surgery and all control groups in more detail.
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2 test, P < .001). When indicators of disease severity (CSS, SAPS II, and TISS [Therapeutic Intervention Scoring System]) and the duration of postoperative ICU treatment were entered as independent variables and PTSD scores as dependent variables into a stepwise regression analysis with backward elimination, the model demonstrated that PTSD scores in the study sample could be predicted from a linear combination of CSS (ß = 0.391, P = .009), SAPS II scores (ß = 0.342, P = .027), and the duration of ICU treatment (ß = 0.363, P = .019) with an intercept of 20.7 and r2 = 0.314. TISS did not add significantly (P = .384) to the ability of the model to predict PTSD scores and was eliminated from the equation.
Patient satisfaction
Patient satisfaction with 20 different aspects of daily life was high, reaching a summary score of all items of 156 (median value; first quartile 124; third quartile 176; Table II
) of a possible maximal value of 200. No statistically significant difference was observed between patients undergoing CABG or AVR (P > .219). Patients from both groups were least satisfied with their degree of physical fitness (rated 6 on the 10-point satisfaction scale) and maximally satisfied with their housing and family situation, their degree of independence, and the medical and surgical treatment they had received (rated 9 on the 10-point scale). There was a statistically significant correlation between life satisfaction summary scores and mental (r = 0.517, P < .001) and physical sum scores (r = 0.492, P < .001) of the SF-36 HRQL measurements.
The relationship between PTSD, HRQL, and patient satisfaction
Patients with evidence of PTSD (n = 12) reported significantly lower SF-36 mental summary scores than emotionally healthy subjects (38.3 vs 48.4, P = .004), with no significant difference regarding physical sum scores (34.0 vs 43.9, P = .173). Other SF-36 indicators of social functioning and mental health were also significantly lower in patients with PTSD (social function: 68.8 vs 87.5, P = .017; vitality: 45 vs 60.0, P = .010; emotional role function: 0.00 vs 66.7, P = .012; or mental health: 52.0 vs 78.0, P
.001). When PTSD scores were entered into a multiple regression model with SF-36 mental health sum scores as a dependent variable and clinical severity scores (CSS), simplified acute physiology (SAPS II) scores, and duration of ICU treatment as independent variables, backward elimination reduced the model to PTSD scores. This then explained variations in mental health sum scores (ß = 0.310, P < .027, intercept = 59.0, r 2 = 0.25), and all other factors were removed from the model (P > .319). A similar relationship was found with regard to life satisfaction. Patients with PTSD reported significantly lower satisfaction sum scores (121.5, first quartile, 111.8; third quartile 144.8 vs 162.0, first quartile, 131.8; third quartile 180.0, P = .002) than emotionally stable patients; likewise, all other life satisfaction items were rated significantly lower (P
.034) with the exception of social support (P = .265), independence (P = .071), marriage/partnership (P = .297), professional, financial, and housing situation (P
.202), and the perceived quality of medical treatment (P = .259). When life satisfaction summary scores were entered into a multiple regression model as a dependent variable and indicators of preoperative disease severity (CSS, SAPS II, TISS, and duration of postoperative mechanical ventilation/ICU therapy) and PTSD scores as independent variables, backward elimination removed all indicators of disease severity, and only PTSD scores explained variations in life satisfaction summary scores (ß = 1.658, r 2 = 0.451, P < .001, intercept = 179.9).
| Discussion |
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However, a subgroup of patients from our sample report significant limitations in psychosocial functioning and pronounced impairments in life satisfaction. These less favorable outcomes were associated with evidence of PTSD in some of these patients. Although this could be a pure correlational association (eg, patients with PTSD may have a bleak outlook on life and a tendency to report a lower HRQL than emotionally healthy individuals), the inverse relationship between PTSD and HRQL has been described in several other studies
25 that used the same method
6 and included patients after prolonged ICU treatment. The overall incidence of PTSD found in our study population is nearly identical to the PTSD frequency described in survivors of a myocardial infarction
11 (without surgical intervention). Furthermore, the dependency of PTSD scores on preoperative indicators of disease severity in our study suggests pre-existing PTSD rather than acquired PTSD during hospitalization, heart surgery, and ICU treatment. An alternative explanation would be that pre-existing mental illness or impairments in social function predispose patients to the development of PTSD and that a lower HRQL is consecutively detected in those patients in whom PTSD develops. Although our method does not allow the definite exclusion of this possibility, pre-existing impairment in social function or low mental health is known to increase the risk for trauma exposure in the community (eg, domestic violence) but does not increase the vulnerability for development of PTSD once a traumatic experience has occurred.
26 The major determinants for PTSD, however, are the intensity of the stressor,
10 probably cortisol levels at the time of stress exposure,
27 and the degree of catecholaminergic activity.
28
Of considerable importance in the diagnosis of PTSD is the definition and intensity of the stressful event leading to the syndrome, which should be "outside the range of usual human experience" and "markedly distressing to almost every one" (criterion A).
10 Physical life threats like acute heart disease are examples of such significant stressors, which could be experienced with "intense fear, terror and helplessness,"
10,29 features that were probably present in the subgroup of our patients in whom PTSD developed. In any case, when evaluating psychologic outcomes from cardiac surgery, the possibility of (probably) pre-existing PTSD must be taken into account. An effort should be made to identify such patients early and to refer them to adequate treatment. Medical treatment of PTSD may consist of tricyclic antidepressants or monoamine oxidase inhibitors. Psychosocial techniques, such as cognitive-behavioral therapy or stress inoculation training, are effective and may be considered as adjunctive therapy.
30
In conclusion, this study addresses the increasingly important issue of assessing HRQL outcome and patient satisfaction after heart surgery and demonstrates a high rate of patient contentment and an acceptable degree of physical and social functioning. Impairments in psychosocial function and life satisfaction were found in a subgroup of patients with evidence of PTSD.
| Footnotes |
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*Note: Higher SF-36 pain scores indicate lower physical pain. ![]()
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