Original article
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Is health-related quality of life an independent predictor of survival in patients with chronic heart failure?

https://doi.org/10.1016/j.jpsychores.2007.06.026Get rights and content

Abstract

Objective

The aim of this study was to examine whether the physical and mental components of health-related quality of life (HRQoL) are independent predictors of survival in patients with chronic heart failure (CHF).

Methods

A cohort of 231 outpatients with CHF was followed prospectively for 986 days (median; interquartile range=664–1120). Generic HRQoL was measured with the Short Form-36 Health Survey (SF-36), disease-specific HRQoL was measured with the Kansas City Cardiomyopathy Questionnaire, and depression was measured with the self-reported Patient Health Questionnaire.

Results

Both generic and disease-specific HRQoL were predictive of survival on univariate analyses. After adjustment for prognostic factors such as age, gender, degree of left ventricular dysfunction, and functional status, only the mental health component of SF-36 and the disease-specific HRQoL remained significant. When depression was included, both measures also lost their predictive power.

Conclusion

Our data suggest that the prognostic value of patients' HRQoL reflects confounding with the severity of disease and comorbid depression.

Introduction

Chronic heart failure (CHF) is associated with a high mortality risk [1] and severely compromises patients' health-related quality of life (HRQoL) [2], [3]. Conflicting evidence exists as to whether HRQoL has, in itself, prognostic power on the prediction of mortality risk. Some [4], [5], [6], [7], [8], but not all [9], studies have found that self-reported HRQoL independently predicted poorer survival in patients with heart failure. Thus, the question on whether patients' subjective health perceptions capture additional prognostic information beyond the information gained from more objective indicators of disease severity, such as left ventricular ejection fraction (LVEF) and degree of physician-rated disease severity, remains unresolved. Moreover, patients' HRQoL is associated with depression [10], and depression has also been found to predict survival [11], [12], [13]. Thus, the prognostic value of patient-reported HRQoL may, at least in part, reflect confounding by depression. If this were the case, the predictive power of HRQoL should be diminished or even lost after adjustment for depression. The current prospective cohort study compares the relative prognostic value of HRQoL, quantitative assessments of left ventricular function, degree of physician-rated disease severity, and depression in CHF patients.

We sought to clarify the following questions: (a) Is HRQoL predictive of reduced survival in patients with CHF after adjusting for established important biomedical variables known to affect survival? (b) If so, does this association hold after including depression as an additional covariate?

Section snippets

Method

Between June 2002 and December 2003, the prospective cohort study “Interdisciplinary Network for Heart Failure” (INH) Würzburg consecutively recruited all patients presenting with CHF of any etiology and severity at two Würzburg University medical centers (N=1054). The present subsample (n=231; participation rate=22%) includes subjects who gave written informed consent to participate in voluntary psychometric assessment. The study was approved by the Ethics Committee of the University of

Descriptive statistics

The descriptive statistics of the study cohort are presented in Table 1. The mean age was 64 years (S.D.=13); 71% were male and 73% were married. CHF etiologies were as follows: coronary heart disease, 43%; dilated cardiomyopathy, 22%; hypertension, 14%; other diseases, in 21%. One hundred twenty-one (52%) patients suffered from systolic heart failure (mean ejection fraction=33.0%), and 108 (47%) suffered from nonsystolic heart failure (mean ejection fraction=56.5%). The distribution of NYHA

Discussion

The aim of our study was to clarify the prognostic value of patient-reported HRQoL. Both generic (SF-36) and disease-specific (KCCQ) measures of HRQoL were predictive of survival on univariate analyses, consistent with previous research [4], [5], [6], [7], [8], [9]. After adjustment for established prognostic factors indicative of disease severity and mortality risk, such as age, left ventricular dysfunction, and NYHA functional class, however, only the mental component of generic HRQoL and the

Limitations

Certain limitations need to be considered in the interpretation of the present findings. We investigated a heterogeneous cohort of patients with CHF across all NYHA functional classes with preserved, as well as reduced, ejection fraction. Considering the number of events and the relatively small sample size of this investigation, we refrained from more detailed analyses of confounders. A further limitation is that self-reports of depression were not confirmed by a structured interview. However,

Conclusion

While patients' self-reported HRQoL is predictive of survival on univariate analysis, it may lose part of its predictive value when either more objective and physician-based measures of disease severity and left ventricular functional impairment or measures of depression are taken into account. However, these results will have to be corroborated by larger studies. Nevertheless, it is important to evaluate patients' HRQoL not only to identify patients with increased mortality risk but also to

Acknowledgments

This study was supported, in part, by the Ernst and Berta Grimmke Foundation (Düsseldorf, Germany) and by an educational grant from Merck (Darmstadt, Germany).

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