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From the College of Nursing (D.K.M.), University of Kentucky, Lexington, Kentucky; the School of Nursing (K.D.), University of California, San Francisco, California; the School of Nursing (L.V.D.), University of California, Los Angeles, California; the School of Nursing (B.R.), San Diego State University, San Diego, California; the University of Technology (S.M.), Sydney, Australia; Tokyo Women’s Medical College Hospital (K.Y.), Tokyo, Japan; the College of Nursing (C-J.K.), Yonsei University, Seoul, South Korea; Ewha Womens University (K.A.), Seoul, South Korea; the Royal Free Hospital (C.B.) and City University (C.B.), London, United Kingdom; and the Coronary Heart Disease Policy Team (M.B.), Department of Health, London, United Kingdom.
Address reprint requests to: Debra K. Moser, RN, DNSc, Professor and Gill Chair of Cardiovascular Nursing, University of Kentucky, College of Nursing, Lexington, KY 40536-0232. Email: dmoser{at}uky.edu
Received for publication February 25, 2002; revision received September 3, 2002.
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ABSTRACT |
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METHODS: In this prospective, comparative study, 912 AMI patients were enrolled from Australia, South Korea, Japan, England, and the United States. Anxiety was assessed, using the Brief Symptom Inventory, within the first 72 hours of admission to the hospital for AMI symptoms.
RESULTS: Women had higher anxiety levels than men (0.76 ± 0.90 vs. 0.57 ± 0.70, p =.005), and this pattern of higher anxiety in women was seen in each country studied. Neither sociodemographic nor clinical variables interacted with gender to influence anxiety.
CONCLUSION: Across a variety of cultures, women have higher anxiety than men after AMI and this relationship is independent of age, education level, marital status, or presence of comorbidities or severity of AMI.
Key Words: anxiety, • gender differences, • acute myocardial infarction.
Abbreviations: AMI = acute myocardial infarction;; ANCOVA = analysis of covariance;; ANOVA = analysis of variance;; CHD = coronary heart disease.
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMETHODSRESULTSDISCUSSIONACKNOWLEDGMENTSREFERENCES |
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Recovery after AMI is influenced by a variety of physiologic, clinical, and psychosocial risk factors that can be modified with appropriate intervention to improve patient outcomes. Physiologic and clinical factors have been studied extensively. Although less thoroughly investigated, the role of psychosocial factors in AMI recovery has recently received increased attention. As a result, clinicians and researchers have come to appreciate the significant independent contribution that these factors make to AMI recovery. Depression (5–8), lack of social support (9–14), and anxiety (15–16) all have been implicated in increased AMI mortality and morbidity.
Anxiety is the most common psychological response to AMI (17). Although it is an expected reaction to some degree, it is not benign. Higher levels of anxiety are associated with increased rates of in-hospital complications, such as reinfarction, recurrent ischemia, and ventricular tachycardia or fibrillation (15), and a higher rate of recurrent cardiac events after the reference infarct (16). Although some investigators have failed to find gender differences in anxiety after AMI (18–20), others report that women are more anxious (21–23).
It is important that gender differences in anxiety after AMI be explored because high anxiety is associated with poorer AMI recovery, and interventions to decrease anxiety levels should be targeted appropriately to those with the highest levels. It is equally important to explore gender differences in other countries to improve the planning of international public health initiatives and the planning of health priorities and initiatives in the United States, which has an increasingly diverse population. Accordingly, the purpose of this study was to determine whether there are gender differences in anxiety, when measured early after AMI, in an international sample. We also sought to determine whether there was an interaction between gender and a number of sociodemographic and clinical variables that may influence anxiety.
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METHODS |
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Patients and Settings
Patients were recruited to participate in this study from the countries of Australia, England, Japan, South Korea, and the United States. Patients were recruited from community hospitals and academic medical centers where they were hospitalized for AMI. They were eligible for the study if they met the following selection criteria: 1) diagnosis of AMI confirmed by elevated cardiac enzymes and standard ECG criteria; 2) AMI occurred outside of a hospital or other institutional setting (eg, extended care facility); 3) free of pain and clinically stable at the time of interview; 4) free of cognitive impairments that might hinder ability to participate in an interview about emotional state; and 5) free of serious debilitating comorbidities such as cancer or renal failure.
Procedures
The study underwent ethical review and was approved by the institutional review boards or their equivalent at each site. This investigation conforms to the principles outlined in the Declaration of Helsinki (see http://www.dvincitbt.com/ohsrsite/guidelines/helsinki.html). Trained research assistants, native to each country, explained the study to eligible patients and obtained signed informed consent for their participation. These research assistants were experienced cardiovascular nurses with training in interview and clinical data collection techniques. Patients were interviewed within 72 hours of admission to the hospital (mean time between admission and interview 53 ± 38 hours) using the Sociodemographic and Clinical Data Form (15) to obtain selected sociodemographic and clinical data and the Anxiety Subscale of the Brief Symptom Inventory (24–25) to determine their anxiety level. In addition, clinical data were obtained from patients’ medical records. Patients were given the option of completing the instrument on their own or having the research assistants read the instrument to them. Most patients chose to have the instrument read to them.
Measurement
Sociodemographic and Clinical Characteristics
Patients were interviewed and their medical record examined to obtain the following sociodemographic and clinical data: gender; age; marital status; education level; history of hypertension, diabetes, and myocardial infarction; Killip classification (range of 1 to 4 with 1 = no signs or symptoms of left ventricular systolic dysfunction and 4 = cardiogenic shock); admission systolic and diastolic blood pressure; admission pulse; patient estimation of level of worst chest pain felt before admission on a scale of 0 to 10 (0 = none, 10 = worst pain ever felt); and medications used during hospitalization.
Anxiety
Anxiety is defined as the emotional response to "anticipation of threats to safety or integrity of body or self" (26). In this study, state anxiety was measured using the anxiety subscale of the Brief Symptom Inventory (24–25). This subscale consists of six items and is useful when studying anxiety in patients with physical illnesses because it is sensitive, brief, reliable, and valid and does not use physical symptoms to indicate feelings of anxiety (24–25). Instruments that include physical indicators of emotions have been criticized for overestimating the level of the emotion being studied in patients with physical illness or disease. Patients rate their level of distress related to a given item on a scale of 0 to 4 (0 = "not at all" and 4 = "extremely"). The scores for the six items are then summed and an average obtained. The range of scores is 0 to 4 and higher scores indicate higher levels of anxiety.
The Brief Symptom Inventory was chosen over the more commonly used Spielberger State-Trait Anxiety for a number of reasons. First, we sought to minimize subject burden, because the patients were acutely ill, and the Brief Symptom Inventory anxiety subscale contains only six items whereas the State-Trait Anxiety Index contains 40 items (20 for each index). Second, the Brief Symptom Inventory has well-established reliability and validity and we have previously demonstrated that it performs reliably and validly in an AMI population (15, 24–25). Third, because the Brief Symptom Inventory is short with simple instructions, it was easier to translate than the more conceptually complex Spielberger. The Spielberger State-Trait Anxiety repeats the same 20 items twice with instructions when measuring state anxiety to rate how one feels now and when measuring trait anxiety to rate how one feels generally. Finally, state and not trait anxiety was the construct of interest.
The Sociodemographic and Clinical Data Form and the Brief Symptom Inventory were translated from English to Korean and Japanese by native-speaking researchers. The instruments were then back-translated into English by a second native-speaking researcher and examined for equality of meaning. In this study, Cronbach 
was used to assess reliability of the anxiety subscale of the BSI and was found to be high at 0.88 for the Australian subgroup, 0.90 for the South Korean subgroup, 0.87 for the Japanese subgroup, 0.90 for the English subgroup, and 0.85 for the U.S. subgroup.
Statistical Analyses
Data are presented as frequencies, means ± standard deviations, or medians with 25th and 75th percentiles. Sample sociodemographic and clinical characteristics between men and women were compared using 
2, independent t test, or ANOVA as appropriate to the level of measurement. To determine whether there were gender differences in anxiety in the countries studied, ANOVA was used with gender and site as factors and the interaction and main effects examined. To determine whether gender was related independently to anxiety or whether it interacted with any of the sociodemographic and clinical characteristics that were different between men and women, either multifactorial ANOVA or ANCOVA were performed.
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RESULTS |
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DISCUSSION |
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The difference in anxiety between men and women was statistically significant, but the absolute difference seems small and a discussion of the clinical significance of our finding is warranted. The mean anxiety level for women in the entire sample was 0.76 and for men was 0.57. Although this seems negligible, it must be interpreted in the context of the scoring scale for the instrument and other considerations. The Brief Symptom Inventory is scored on a scale of 0 to 4, with a norm of 0.35; thus seemingly small differences can be clinically significant. Viewed from another perspective, there was a 25% difference in anxiety level reported between women and men. Twice as many women as men in the sample reported anxiety in the extreme ranges. Further evidence of the clinical importance of the difference in anxiety between the genders seen in this study can be found from studies of the association between anxiety and in-hospital complications. In a previous study, in which the Brief Symptom Inventory was used to measure anxiety, we demonstrated that higher levels of anxiety were associated independently with greater risk of in-hospital complications (15). In this study, the difference in anxiety between those with and without complications was as low as 20%, thus providing evidence of the clinical significance of the difference in anxiety between genders seen in the current study.
Although many investigators have found no gender differences in anxiety after AMI (18–20), others have reported that women were more anxious (21–23, 28–31). Small sample sizes with decreased power to find differences (19–20) and markedly smaller numbers of women compared with men enrolled in studies (18–22) likely contribute to inconsistency in demonstrating gender differences. In a recent study with a large U.S. sample and proportionally more women than previous investigations, we demonstrated significantly higher anxiety in women early after AMI (23). The present study also had proportionally more women than most prior studies. Thus, in appropriately powered studies, gender differences in anxiety are evident. Higher levels of anxiety in women are reported consistently across cultures in nonclinical populations (32). Our finding of higher anxiety among women across the cultural groups is consistent with this literature but is the first cross-cultural comparison reported in patients hospitalized for AMI.
When women present with AMI, they typically are different than men in a number of characteristics including age, marital status, education level, income, and presence of comorbidities (30, 33–35) . Investigators have suggested that these differences may explain gender differences in anxiety after AMI. For example, Czajkowski and colleagues (36) suggested that higher anxiety in women having coronary artery bypass grafting may be related to income, age, marital status, and other characteristics reflecting social roles. They proposed that the older age of women than men at the time of infarction, and the fact that women are more likely to be single or widowed and more likely to have lower income, might explain their higher anxiety.
As in other AMI studies, the women enrolled in our study from each country were older than the men, had less formal education, and were more often widowed, divorced, or single than married. Yet, when we examined the potential impact on anxiety of the interaction of these and other clinical factors with gender, there was no interactive effect. Consistent with prior research (37), younger patients had higher anxiety levels than older ones, but this finding was true of both men and women. In our prior study of gender differences in anxiety after AMI in the United States, we also found that few sociodemographic and no clinical variables interacted with gender to influence anxiety (23). Thus, the relationship between gender and anxiety cannot be explained by differences in sociodemographic and clinical characteristics at the time of presentation for AMI between men and women.
The overall anxiety levels seen in this diverse group of AMI patients regardless of gender were appreciably (44%) higher than the normative levels for nonpatients but were lower than the norms for psychiatric patients (25). It is likely that an even higher level of anxiety would have been evident if we had been able to measure anxiety very early (within the first 12 hours) after admission to the hospital with confirmed AMI, but it is difficult to capture patients for research purposes during that critical time period. The average time to measurement of anxiety in this study was 53 ± 38 hours.
Increased anxiety after AMI has been documented by others for several decades and continues to be a concern (15–16, 30, 38–39) . The level of anxiety in post-AMI patients has not been documented across a variety of countries. The finding that these levels of anxiety do not differ among the six countries is intriguing given the expectation that the emotional reaction to the threats to safety or body engendered by the AMI process are expressed in unique ways based on cultural context (26). A common conception among health care providers is that patients from Southeast and Eastern Asian cultures express less emotion based on a belief system that values maintenance of harmony with avoidance of strong emotions (40).
Cross-cultural comparisons of psychosocial variables, including dysphoric states, are rare among cardiac patient populations so it is difficult to make conclusive arguments regarding which groups might express higher or lower levels of psychological distress. In one study of a nonpatient group of Japanese, European, and American university students, Japanese subjects reported lower fear intensity, less expression of fear when experiencing it, and strikingly less physiological response to fear (41). However, the few studies conducted among cardiac patients from Asian countries suggest that they experience and express anxiety and uncertainty related to cardiac events and procedures to a degree similar to American patients (42–43). Furthermore, large epidemiologic studies demonstrate no wide cross-cultural variation in the presence of various depressive and anxiety disorders (32). Similarly, somatization of anxiety and depression seems to be a common reaction across a variety of cultures to the distress of these emotions (26). Thus, our finding of no significant differences in the expression of anxiety among the various countries suggests that the threatening nature of AMI produces anxiety regardless of the patient’s cultural overlay.
A potential limitation of this study is the use of an instrument to measure anxiety across cultures that was developed in the United States. Although the instrument was translated and back-translated into each language by native speakers and was administered by native research assistants, the instrument was not developed with different cultural influences in mind. Thus, it could be argued that it may have spuriously elevated or decreased anxiety levels if items were not culturally sensitive. Although further work is necessary to confirm the reliability and validity of the instrument in non-English-speaking patients, the high reliability coefficients of the instrument in each country studied and the consistency of findings provide preliminary evidence that this instrument performed satisfactorily in this sample.
Another limitation of this study is the lack of a pre-AMI anxiety measure. Without a baseline measure of anxiety, we cannot conclusively attribute the anxiety we measured solely to the AMI experience itself. In long-term longitudinal studies, investigators have demonstrated that pre-existing anxiety is associated with higher risk of sudden cardiac death and AMI (39, 44). Thus, it may be that many individuals come to the AMI experience with pre-existing anxiety and the anxiety seen after AMI is the continuation of this anxiety. However, regardless of whether the anxiety measured after AMI is a result of reaction to the experience or the accumulation of pre-existing anxiety and response to the AMI, women express higher levels during this time period.
To summarize, women are more anxious after AMI than men, and this finding is consistent across a variety of Western and Asian cultural groups. The relationship between gender and anxiety seems to be independent of the influence of sociodemographic and clinical variables. A fruitful area for future research includes investigation of reasons why women of different cultures all seem to be at higher risk for anxiety after AMI. Other important areas for investigation include determining whether higher anxiety after AMI contributes to the poorer prognosis seen in women and determining the best methods for managing anxiety in busy hospitals. The mechanisms (either physiological or behavioral) whereby anxiety is related to poorer short- and long-term outcomes in AMI patients have yet to be elucidated. Research in this area is important to help clinicians determine the best ways to manage AMI patients to decrease the negative impact of anxiety. Without understanding the basic underlying mechanisms, it is difficult to know whether treatment should concentrate on pharmacological strategies such as beta-blocker therapy to decrease sympathetic nervous system responses to anxiety or more directly on antianxiety drug therapy. The role of nonpharmacologic strategies that decrease psychophysiologic arousal also should be investigated. Despite the need for such research, the results of the present study are noteworthy for clinicians seeking to improve patient comfort and to reduce the harmful consequences of anxiety.
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ACKNOWLEDGMENTS |
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60 and <60 years of age (p = .51 for interaction of age and gender, p = .02 for main effect of age, and p = .001 for main effect of gender).