Research report
Somatic/affective symptoms, but not cognitive/affective symptoms, of depression after acute coronary syndrome are associated with 12-month all-cause mortality

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Abstract

Background

Symptom dimensions of post myocardial infarction (MI) depression may be differently related to prognosis. Somatic/affective symptoms appear to be associated with a worse cardiac outcome than cognitive/affective symptoms. We examined the relationship between depressive symptom dimensions following acute coronary syndrome (ACS) and both disease severity and all-cause mortality.

Methods

Patients (n = 913) who had unstable angina pectoris or MI were recruited from 12 coronary care units between 1997 and 1999. Measurements included sociodemographic and clinical data and the Beck Depression Inventory (BDI). Endpoint was all-cause mortality at 12-month follow-up.

Results

Principal component analysis revealed two components, somatic/affective and cognitive/affective symptoms of depression. Somatic/affective symptoms of depression (odds ratio (OR): 1.49; 95% confidence interval (CI): 1.23–1.81; p < 0.001) but not cognitive/affective symptoms (OR: 0.92; 95% CI: 0.75–1.12; p = 0.40) were related to a higher Killip class. Fifty-one patients died during the follow-up period. When controlling for index event, history of MI, Killip class, diabetes, gender and age, there was a significant association between the somatic/affective component (OR: 1.92; 95% CI: 1.36–2.71; p < 0.001) and mortality. The cognitive/affective component was not related to mortality (OR: 1.07; 95% CI: 0.75–1.52; p = 0.73).

Limitations

Time to death was not available.

Conclusions

This study showed that only somatic/affective depressive symptoms were associated with disease severity and all-cause mortality in ACS patients. More research is needed to evaluate the differential associations of somatic/affective and cognitive/affective depressive symptoms with cardiac outcomes and the underlying mechanisms.

Introduction

During the last decades, substantial research has focused on the association between depression after myocardial infarction (MI) and prognosis, with most studies concluding that depression is related to adverse outcome (van Melle et al., 2004, Barth et al., 2004, Sørensen et al., 2005, Nicholson et al., 2006). The authors of one meta-analysis concluded that depression is a risk factor for poor prognosis in patients with coronary heart disease (CHD) (Barth et al., 2004). The authors of several other systematic reviews and meta-analyses, however, cautioned that there is not sufficient evidence to consider depression an independent risk factor due to methodological issues in existing prognostic studies, including incomplete adjustment for conventional risk factors and cardiovascular disease severity (van Melle et al., 2004, Sørensen et al., 2005, Nicholson et al., 2006). The authors of one of the meta-analyses, for example, noted that adjustment for left ventricular ejection fraction (LVEF) in 8 studies reduced risk estimates of depression on cardiac outcomes by almost 50%, but only 8 of 34 studies in their review adjusted for LVEF (Nicholson et al., 2006). Therefore, it is still unclear whether depression is an independent risk factor or if the relationship between depression and adverse prognosis is influenced by inadequate adjustment for confounding due to traditional risk factors and cardiovascular disease severity.

Recently, several studies have reported that somatic/affective symptoms of depression (e.g., fatigue, sleep problems, and poor appetite), but not cognitive/affective symptoms (e.g., shame, guilt and negative self-image), were related to adverse cardiac prognosis following an MI (de Jonge et al., 2006, Smolderen et al., 2009, Martens et al., 2010). Somatic/affective symptoms were associated with disease severity, but after controlling for disease severity the association of somatic/affective symptoms with cardiac prognosis remained statistically significant (de Jonge et al., 2006, Smolderen et al., 2009, Martens et al., 2010). This finding has also been reported among patients with chronic heart failure (Schiffer et al., 2009) and women with suspected myocardial ischemia (Linke et al., 2009). In each of these studies, somatic/affective symptoms, but not cognitive/affective symptoms, were statistically significantly related to cardiac outcome. However, in each study, the confidence intervals for risk related to somatic/affective and cognitive/affective symptoms overlapped.

In the present study, we investigated the associations of somatic/affective and cognitive/affective symptom dimensions of depression among acute coronary syndrome (ACS) patients with disease severity and all-cause mortality. We hypothesized that somatic/affective depressive symptoms would be associated with disease severity and that after controlling for cardiac risk factors, including disease severity, only the somatic/affective dimension of depressive symptoms would be associated with adverse outcome.

Section snippets

Study design and patient population

This was a prospective study following patients admitted with ACS to 12 coronary care units (CCU) across South-central Ontario, Canada, for 1 year. The methods of the study have been described previously (Grace et al., 2005). Participants (18 years and older) who were diagnosed with a confirmed MI or unstable angina pectoris (UA) after appropriate diagnostic tests were recruited between August 1997 and January 1999 in the CCU by a research nurse on the 2nd to 5th day of hospitalization. Patients

In-hospital depression

Of the original 913 patients, 28 were excluded due to incomplete BDI responses and 11 for missing information on survival status, leaving 874 patients to be included in further analyses. Of the 874 patients, 297 (34%) had a BDI score of 10 or higher, which is comparable to previous research (van Melle et al., 2004). Table 1 shows demographic and clinical characteristics of the sample.

Component structure

The KMO test (0.93) and Barlett's test of sphericity (p < 0.001) showed that PCA was adequate for these data.

Discussion

This study is the first to examine the associations between somatic/affective and cognitive/affective depressive symptoms with all-cause mortality in a large combined sample of patients who had experienced an MI or UA. The dimensional structure of depressive symptoms was similar to the structures found in earlier studies (de Jonge et al., 2006, Martens et al., 2010). Somatic/affective depressive symptoms were associated with Killip class while cognitive/affective depressive symptoms were not.

Role of the funding source

This research was conducted with funds from the Heart and Stroke Foundation of Ontario and the Samuel Lunenfeld Foundation of Toronto, Ontario, awarded to Dr. Stewart and Dr. Abbey. Dr. Thombs is supported by a New Investigator Award from the Canadian Institutes of Health Research and an Établissement de Jeunes Chercheurs award from the Fonds de la Recherche en Santé Québec. Dr. Grace is also supported by a New Investigator Award from the Canadian Institutes of Health Research. Dr. de Jonge is

Conflict of interest

None.

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