Are illness perceptions about coronary artery disease predictive of depression and quality of life outcomes?

https://doi.org/10.1016/j.jpsychores.2008.09.005Get rights and content

Abstract

Objective

Depression occurs commonly in coronary artery disease (CAD) and is associated with substantial disability. Modifiable cognitive determinants of depression in this population have not been identified. We investigated the impact of potentially modifiable illness beliefs about CAD on depressive symptomatology. We also examined the association between these beliefs and health-related quality of life (HRQOL) and socio-demographic variations in illness beliefs.

Methods

A prospective study of 193 recently hospitalized CAD patients was conducted. Data were collected from medical records and by self-report 3 and 9 months post-discharge. Socio-demographic differences were analysed with independent sample t-tests. Predictive models were tested in a series of hierarchical linear regression equations that controlled for known clinical, psychosocial, and demographic correlates of outcome.

Results

Negative illness beliefs, particularly those associated with the consequences of CAD, were significantly predictive of higher levels of depressive symptomatology at 3 and 9 months. Positive illness perceptions were significantly associated with better HRQOL outcomes. Older and less socially advantaged patients demonstrated more negative illness beliefs.

Conclusions

Illness beliefs are significantly associated with depressive symptomatology and HRQOL in CAD patients. These beliefs can be easily identified and constitute a meaningful and clinically accessible avenue for improving psychological morbidity and HRQOL in CAD patients. Older and more socially vulnerable patients may require heightened monitoring of their illness beliefs. Research needs to translate these and other predictive findings into interventions.

Introduction

Coronary artery disease (CAD) is a leading cause of disability in many developed countries, including Australia, where it is the foremost source of total disease burden [1]. Compelling epidemiological evidence indicates disproportionately high rates of depression in patients with CAD [2], [3], [4], [5], [6], [7], [8] and shows that this co-morbidity is associated with at least a twofold increased risk for future cardiac events [2], [9], [10], [11]. Despite recognition of the prevalence and prognostic significance of depression in patients with CAD, relatively little is known about psychosocial factors involved in the aetiology of depression in this population. Several studies have examined the associations between disease-related [5], [12], [13], [14] and socio-demographic risk factors [15], [16], [17], [18] and depression, but the therapeutic value of these data is limited by the inability to modify these variables to improve outcome. The identification of modifiable determinants of depression in CAD patients is therefore a priority.

One promising psychological approach relates to patients' personal beliefs about their illness. Mounting empirical evidence from a range of disease groups (e.g., cancer, psoriasis, asthma, diabetes, haemophilia, and chronic fatigue syndrome [19], [20], [21], [22], [23], [24]), including CAD [25], [26], [27], [28], [29], [30], [31], [32], suggests that these illness beliefs are key determinants of recovery and may represent a potential target for clinical intervention. The association between these personal illness perceptions and recovery is based on a theory of self-regulation [33] that posits individuals as active problem solvers who, in response to illness and other health threats, develop parallel cognitive and emotional representations of the threat. These cognitive illness representations include the number and actual experience of symptoms endorsed as being part of the illness as well as the abstract label given to these symptoms (identity); expectations about the likely duration of the illness (timeline); beliefs about the physical, social, and emotional effects (consequences); perceptions of the extent to which it is amenable to cure or/and control; and beliefs regarding the cause(s) of the condition. According to the theory [33], these combined illness representations provide patients with a conceptual framework in which to process health care advice, which, in turn, determines adjustment to illness.

Amongst patients with CAD, illness beliefs have predominantly been investigated in relation to their impact on adherence to health behaviours, particularly attendance at cardiac rehabilitation [25], [26], [27], [28], [29], [32]. The association between beliefs about CAD and depression has received little attention [25], [29], [30], [31]. One prior study (N=105) investigated the prospective association between illness beliefs and depression and found that changes in angina beliefs over 1 year made near significant contributions (P=.06) to the variance in depressive symptomatology on the Hospital Anxiety and Depression Scale (HADS) [34]. Illness beliefs may impact on other outcomes including health-related quality of life (HRQOL). HRQOL is increasingly recognized as a valued outcome in CAD patients [35], [36] and is reported to predict cardiac end points [37], [38], [39].

The primary aim of the present study was to further investigate the association between illness beliefs and depression. As a secondary outcome, the present study also investigated the extent to which illness beliefs are associated with HRQOL. Since no prior study has investigated illness beliefs in an Australian sample, we also investigated whether these beliefs vary with gender, socioeconomic status (SES), and age.

Consistent with cognitive theories of depression that posit negative cognitive appraisals as a vulnerability for depression [40], [41], we hypothesized that negative or catastrophic perceptions about CAD would predict greater depressive symptomatology. It was also hypothesized that more positive illness appraisals would predict better HRQOL.

Section snippets

Method

To investigate our hypotheses, we conducted a study with recently hospitalized CAD patients in which clinical variables (CAD disease severity, smoking, and co-morbid diabetes) and known socio-demographic (gender [5], [15], [17], [42], age [15], [16], [18], [43], SES [42], [44], [45]) and psychosocial (social support [5], [15], [46], [47], neuroticism [48], [49], [50]) correlates of depression and HRQOL were controlled a priori. Outcome was assessed at two time points to enable analysis of the

Characteristics of the sample

T1 questionnaires were completed by 193 (84%) of the 229 recruited patients. This translates to 37% of the original number of patients treated during the study period, including patients deceased at recruitment and those not eligible for participation. Compared to these nonparticipants, participants were significantly more likely to be male [χ2(1, N=528)=5.93, P=.02] and were, on average, younger [t(526)=3.12, P<.01]. The mean (S.D.) age for participants vs. nonparticipants was 64.14 (10.37)

Discussion

Consistent with our a priori predictions, negative illness appraisals, particularly those associated with the consequences of CAD, were predictive of higher levels of depressive symptomatology at 3 and 9 months following discharge from hospital. This association was statistically significant in the presence of well-known clinical and demographic correlates of depression and the psychosocial risk factors of neuroticism and social support. Although beliefs about consequences contributed modestly

Conclusion

Our findings suggest that illness beliefs are significantly associated with depressive symptomatology and HRQOL in CAD patients. Illness beliefs constitute a meaningful and clinically accessible avenue for improving psychological morbidity and HRQOL in CAD patients, possibly with mitigating effects on cardiac prognosis. It is appropriate for researchers to translate these and other positive findings into interventions of the type described above.

Acknowledgments

We acknowledge Jeromy Anglim for his statistical advice.

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