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Psychological and Social Factors That Correlate With Dyspnea in Heart Failure

Received June 28, 2005; revised February 2, 2006; accepted February 9, 2006. From the Dept. of Psychiatry and Dept. of Medicine–Cardiology, Robert Wood Johnson Medical School, Univ. of Medicine and Dentistry of New Jersey, New Brunswick; the Dept. of Psychology, LaSalle Univ., Philadelphia, PA; and the Dept. of Behavioral Cardiology, Columbia Univ., New York, NY. Address correspondence and reprint requests to Dr. Skotzko, Dept. of Psychiatry, Robert Wood Johnson Medical School, Univ. of Medicine and Dentistry of New Jersey, New Brunswick, NJ 08903. e-mail: skotzkce{at}umdnj.edu

ABSTRACT

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Dyspnea is a common symptom of heart failure frequently relied upon to assess clinical functioning. The purpose of this study is to explore a broad range of medical, psychological, and social factors that correlate with dyspnea in heart failure patients. Seventy-six participants ranged from well-compensated, ambulatory subjects to those with recent hospitalization for acutely decompensated heart failure. The sample was predominantly male, mean age of 63.5 years, with mild depressive symptoms in 25%. Correlation analysis revealed that dyspnea significantly correlated with depression, fatigue, and overall health perception. Standard regression analyses indicated that depression, fatigue, and overall health perception uniquely contributed to dyspnea, explaining 38.0% of the total variance. The present study confirms that dyspnea is multifactorial, with links to psychological distress and overall health perception.

INTRODUCTION

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Dyspnea is defined as an uncomfortable sensation in breathing,¹ and it is a common symptom associated with moderate-to-severe heart failure. As heart failure progresses, dyspnea becomes increasingly troublesome for individuals and frequently worsens their quality of life. Despite its high prevalence, the pathophysiology of dyspnea is still not well understood.^1–3 It remains one of the most refractory symptoms of advanced heart failure.

Dyspnea cannot always be explained by organic etiologies,^2,3 and it should be distinguished from respiratory failure, defined as hypoxia or hypercapnia. The experience of dyspnea is thought to be influenced by activity at many levels of the nervous system, including the respiratory centers in the medulla and the cortex.⁴ The manifestations of subjective symptoms have recently come to be interpreted as resulting from the interaction of perception and expression, rather than as a direct representation of the intensity of effects at the receptor level.⁵

Dyspnea negatively affects an individual’s overall quality of life, and several psychosocial variables have been proposed to elucidate the relationship between dyspnea and perceptions of well-being. Previous studies have examined psychosocial correlates of dyspnea in patients with chronic obstructive pulmonary disease (COPD),^6–8 cancer,⁹ and those requiring mechanical ventilation.¹⁰ Systematic studies focused on correlating factors with perception and expression of dyspnea in heart-failure patients have yet to be conducted. The purpose of this study is to identify factors correlated with dyspnea in heart-failure patients, examining a range of medical, psychological, and social factors suggested by previous research in other patient populations and recent investigations of depression in patients with heart failure.¹¹

METHOD

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Sixty-seven individuals with chronic, non-valvular heart failure comprised our sample. Participants ranged from well-compensated, ambulatory subjects (N=20) to those with recent hospitalization for acute, decompensated heart failure (N=47). All completed self-report questionnaires in the ambulatory or acute hospital settings. All subjects were free from cognitive disorders (Mini-Mental State Exam score >21). Exclusion criteria were active suicidal ideation (N=1), terminal pulmonary/hepatic/renal disease, acute active infection, and active oncologic process requiring chemotherapy or radiation. Chart reviews were used to screen hospitalized individuals before approaching them for their consent to participate. The research was approved by the Institutional Review Board of the Robert Wood Johnson Medical School of the University of Medicine and Dentistry of New Jersey.

Measures
The Dyspnea Scale¹² was used to assess shortness of breath; it has four Yes/No questions on the degree of functional impairment and the magnitude effort of the tasks that precipitate breathlessness. Reliability and validity for this scale have been demonstrated in large clinical trials in heart-failure patients.¹³ The total score ranges from 0 to 12, with higher scores indicating greater impairment.

The Hospital Anxiety and Depression Scale (HADS) was developed to measure anxiety and depression specifically in patients with chronic disease. It is a 4-point, 14-item, self-assessment scale that measures anxiety and depression separately.¹⁴ The full score is 21 points each for anxiety and depression. The scores can be interpreted in the following way: normal: 0–7; mild: 8–10; and moderate-to-severe: 11–21.¹⁵ Reliability and validity for this scale have been demonstrated in large clinical trials.¹⁶

General/overall health was assessed with a questionnaire about perception of health status and was adapted from the General Health items from the SF–36,¹⁷ which has been tested and found valid in individuals with congestive heart failure.¹⁸ Three Likert-scale items were used for assessment of global subjective health: "In general, would you say your health is: very good, good, fair, poor;" "I am somewhat ill: definitely true, true, false, definitely false"; and "I am as healthy as anybody I know in my condition: definitely true, true, false, definitely false." The three items were combined into a single factor, reflecting global perceived health, with higher score implying better perception of health. In a previous study of patients with left-ventricular dysfunction, this factor correlated highly with individual item scores (r>0.85), and was internally consistent.¹⁹ Such global health ratings have correlated highly with overall measures of quality of life and predicted mortality.^20,21

Physical functioning was assessed with the 10-item Physical Functioning scale from the Short Form SF–36.^17,18 The item scores range from 0 to 2 (0: no, not limited at all; 1: limited a little; 2: yes, limited a lot). The total scale score ranges from 0 to 20. Higher scores indicate greater impact of health problems on performance of routine physical activities.

We used an abbreviated visual-analog scale similar to that used by Lee²² to assess the severity of subjects’ fatigue. The scale ranged from 0 to 10 ("not at all" to "a great deal"). Three items, examining the 1) degree of fatigue, 2) severity of fatigue, and 3) distress associated with fatigue were utilized. The total scores ranged from 0 to 30, with higher scores indicate greater fatigue.

The sleep questionnaire was adapted from the Generalized Anxiety Disorder module of the SCID,²³ and it had three questions asking patients about sleep during the past week. The questions are about falling asleep, staying asleep, and feeling unrefreshed after sleeping. The scores ranged from 0 to 9, with higher scores indicating greater sleep problems.

Statistical Analysis
We analyzed the data with SPSS (Statistical Package for Social Sciences) Version 7.5 for Windows (SPSS Inc, Chicago, IL, 1997). Pearson’s product-moment correlations were calculated between dyspnea and fatigue, depression, anxiety, overall health, activities of daily living, and sleep. Standard regression analyses were used to explore the unique contributions of variables significantly correlated with dyspnea.

RESULTS

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Table 1 reports the means and standard deviations (SDs) of the reported measured outcome variables. Regression equations for each variable were derived using gender and age as predictor variables, given that both variables had little missing data. Correlations were calculated between variables with both original and modeled data. Significance levels for correlations were not different between original and modeled data sets, so only the original analyses are reported, with appropriate degrees of freedom noted.

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TABLE 1. Summary Statistics for Outcome Variables

There were more men (N=44) than women (N=21), and the majority of the sample was over age 60 (mean: 65.4; SD: 14.05). For the HADS Depression subscale, 25% of the patients had mild (score: 7–11; 20%)-to-severe (score: >12; 5%) depressive symptoms. Individual-sample t-tests examining the effect of gender on the other variables indicated no significant differences between men and women.

Dyspnea was moderately positively correlated with the HADS Depression subscale score (r=0.40, df: 46, p<0.01), and fatigue (r=0.62, df: 36, p<0.01). There was a significant negative correlation between dyspnea and overall health (r=–0.42, df: 36, p<0.05). Dyspnea was not significantly correlated with the HADS Anxiety subscale score (r=–0.04, df: 46, p<0.77), physical functioning (r=0.22, df: 32, p<0.23), or sleep disturbance (r=0.26, df: 41, p<0.11). The relationship between sleep disturbance and HADS Depression subscale score was also nonsignificant (r=0.25, df: 41, p<0.12). Also, no significant correlations were found among the variables (HADS Depression subscale score, fatigue, length of hospital stay, and overall health) that were significantly related to dyspnea, so covariance analyses to explore potential mediation effects that might have been considered were not appropriate. The significant relationships found between dyspnea and the other variables are summarized in Figure 1. Standard regression analyses indicated that Depression subscale scores, fatigue, and overall health significantly predicted dyspnea (R²=0.38; F=7.87, df: 36, p<0.01). Depression subscale score (ß=0.56, p<0.01), fatigue (ß=0.39, p<0.05), and overall health (ß=0.41, p<0.01) each uniquely contributed to the variability in dyspnea scores.

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FIGURE 1.  Summary of Significant Correlations *p < 0.05; **p < 0.01.

DISCUSSION

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The present study found dyspnea to be meaningfully related to fatigue, perceptions of health, and depression symptoms. Previous research has clearly demonstrated a link between fatigue, perceptions of health, and dyspnea in individuals with heart failure;^24–26 however, the relationship between depression and dyspnea in heart-failure populations has received less attention and is a key finding in the present study. Previous studies have documented evidence of depression in patients with heart failure.^27,28 Depression has been shown to be an independent risk factor for increased morbidity and mortality associated with heart failure,^11,29 and is thus a potentially serious problem in patients with heart failure. A recent study has estimated that the prevalence of depression in heart-failure patients ranges from 24% to 42%.³⁰ The present study corroborates this finding: 25% of the current sample reported mild-to-severe depression symptoms. Unfortunately, the specific nature of the relationship between heart failure and depression has received limited attention in the literature.

The present study found that dyspnea, a common complication of heart failure, is uniquely correlated to depression, supporting the hypothesis for links between dyspnea, heart failure, and depression. Dyspnea has been found to be correlated with depression symptoms in asthma,⁶ cancer,⁹ and mechanically ventilated patients.¹⁰ The current study was the first to find a significant correlation between dyspnea and depression in heart-failure patients. Furthermore, the contribution of depression is significant even when accounting for the contribution of overall health and fatigue, suggesting that the impact of depression on dyspnea may be more than the overlap in physical symptoms between the two phenomena.

The recognition and management of depression in patients with heart failure poses challenges for psychiatrists and cardiologists. It is pertinent to consider how depression may affect dyspnea management in heart-failure patients. Sertraline, a selective serotonin reuptake inhibitor (SSRI), has been shown to relieve dyspnea as well as depressive symptoms in patients with COPD.³¹ Indirect evidence from SSRI treatment of dyspnea suggests that serotonin may be involved in the modulation of dyspnea and control of respiration.³¹ Successful treatment of depression symptoms may substantially lessen dyspnea and improve quality of life in patients with heart failure.

Thomas et al.²⁷ reported that the gold standard of assessment of dyspnea is based on patient self-report, rather than objective measures. Furthermore, objective measures such as respiratory rate, oxygen saturation, and arterial blood gas measurement do not frequently correlate with the subjective experience of dyspnea.⁶ The data from our study supported this conclusion, as dyspnea scores did not significantly correlate with reports of physical functioning but did correlate (negatively) with perception of health. We found that depression symptoms were positively correlated with dyspnea, suggesting that depression may alter perception of health. Further research is needed to attempt to replicate the present findings. Additional investigation of the relationship between depression symptoms and both subjective and objective measures of dyspnea are warranted.

Interestingly, whereas anxiety has been found to be correlated with dyspnea in patients with pulmonary disease,³² the present study did not find a significant relationship between dyspnea and anxiety. Also, dyspnea was not meaningfully related to sleep or activities of daily living. This finding is surprising, because research with COPD patients has found that dyspnea typically leads to inactivity, with subsequent physical deconditioning³³ and sleep disturbances.³⁴ The reasons dyspnea relates differently to physical functioning and sleep in heart-failure patients is an empirical question to be further studied.

The limitations of this study are evident. The sample size was small and may have provided too little statistical power to detect true relationships between dyspnea and several of the investigated variables. Missing data were also a problem that further limited power, although significance levels for correlations were not different between original and modeled data sets supporting the reported data. Much of the missing data were seen in the hospitalized cohort, despite our efforts to minimize the respondent burden. In the future, providing assistance in completing questionnaires might offset this problem.

In future research, it will be important to investigate whether the relationships found between dyspnea and depression can be replicated. Larger samples would allow further elucidation of the unique contributions of dyspnea and depression to the clinical picture in heart-failure patients and provide enough statistical power to detect potentially clinically significant relationships between measures of psychological and physical functioning in these patients.

Prospective studies would also allow for testing of the potential mediating effect of dyspnea on the relationship between baseline depression, fatigue, and perception of health. An interesting future investigation would also be to test for mediation effects in the relationship between dyspnea and depression. In the current study, sleep disturbance was the best candidate because it correlated with both depression and dyspnea, and sleep disturbances are likely to follow the onset of dyspnea, which justifies its evaluation as a potential mediator or causal process. The relationships between sleep, dyspnea, and depression did not reach statistical significance; however, the current study was likely underpowered to detect such significance, and, with a larger sample, the relationship between these variables could be tested with enough statistical power to determine any mediation or moderation effects. Lastly, the potential for SSRIs to affect perception of dyspnea and potentially improve quality of life in individuals is intriguing and deserves further attention.

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Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Email this article to a Colleague Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to My Articles & Searches Download to citation manager Citing Articles via Google Scholar Articles by Ramasamy, R. Articles by Skotzko, C. Search for Related Content PubMed Citation Articles by Ramasamy, R. Articles by Skotzko, C. Anxiety Disorders (General) Depression Syndromes Secondary to General Medical Disorders

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