The EQ-5D in alcohol dependent patients: Relationships among health-related quality of life, psychopathology and social functioning

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Abstract

Objective

The EQ-5D, a short generic health-related quality of life (HRQOL) questionnaire, can derive preference-based index scores (e.g. EQ VAS, British and German EQ-5D indices) for economic evaluation. This study examined if the EQ-5D could be a valid measure describing and valuing HRQOL in alcohol dependent individuals.

Methods

In a sample of 103 individuals diagnosed with alcohol dependence (ICD-10 F10.2), we compared the EQ-5D against a quality of life measure (WHOQoL-BREF), a utility scale (TTO), measures of psychopathology (SCL-90R, CGI-S) and measures of social functioning (GAF, GARF, SOFAS, HoNOS).

Results

The response rate to EQ-5D dimensions was >98%. Twelve percent of the individuals indicated “extreme problems” in at least one dimension. Different response levels in the dimension “anxiety/depression” were associated with largest effect sizes (|d|) of differences in mean scores of the WHOQoL-BREF domain “mental” (|d| = 1.17), the SCL-90R scales “obsessive-compulsive” (|d| = 1.15), “depression” (|d| = 1.16), “anxiety” (|d| = 1.10) and “GSI” (|d| = 1.09) indicating a similarity between the underlying constructs; concerning the dimensions “self-care”, “usual activities”, “pain/discomfort” and “mobility” effect sizes were generally lower (0.74 < |d| < 1.07) or insignificant. The EQ-5D VAS score (mean 58.0), the British EQ-5D index (mean 0.74) and the German EQ-5D index (mean 0.85) showed moderate correlations with other scales (0.28 < r < 0.60).

Conclusion

Seventeen out of 30 hypothesized relationships between similar constructs of the EQ-5D and measures used for comparison were confirmed, possibly favoring EQ-5D's validity. However, the EQ-5D showed a moderate ceiling effect. Further confirmatory research is needed to support the EQ-5D suitability for economic evaluation in alcohol dependent populations.

Introduction

Alcohol use disorders are a major public health issue estimated to affect 5–15% of adults in OECD-States (Grant, 1997, Bronisch and Wittchen, 1992). The medical, social and economic consequences of alcohol use disorders cause considerable direct and indirect costs each year (Reynaud et al., 2001, Rice et al., 1991). Given the prevalence and importance of this condition, little information is available regarding the effect of alcohol use disorders on health-related quality of life (HRQOL).

HRQOL represents the effects of an illness upon the physical, mental and social dimensions of the individual's well-being. Instruments used to measure HRQOL may be disease-specific or generic. As there is no alcohol-specific HRQOL questionnaire, the few studies assessing HRQOL to date in individuals with alcohol use disorders have used generic instruments designed to measure a subject's overall HRQOL. They may be used to compare the HRQOL of subject groups across different diseases and may provide useful information for decisions on health policies.

The majority of studies used the Short-Form-36 (SF-36) (Ware and Sherbourne, 1992) as a generic measure (Romeis et al., 1999, Daeppen et al., 1998, Volk et al., 1997). Moreover, the Nottingham Health Profile and, more recently, the WHOQol-BREF developed by the World Health Organization were used to measure quality of life in alcohol dependent subjects as well (Foster et al., 1998, Silva Lima da et al., 2005). All studies reported that the HRQOL of subjects with alcohol use disorders was poor compared to that of a reference population.

The EQ-5D is a short generic questionnaire which differs from all types of above mentioned generic HRQOL measures in one fundamental way: the EQ-5D consists of a description and also a valuation of HRQOL as a summarized single index score reflecting individuals’ preferences for different health states (The EuroQol Group, 1990, Brooks, 1996). In addition, for various countries (included United Kingdom, Germany and the United States) an index score is available that is assigned to an EQ-5D health state according to a particular set of preference values derived from surveys of the general population (Dolan, 1997, Greiner et al., 2005, Shaw et al., 2005). The individual respondents’ index scores and/or index scores derived from the general population might be used in evaluating changes in health status, with the former reflecting the preferences of beneficiaries of care and the latter reflecting community preferences (Dolan, 1999). For the purpose of cost–utility analysis in economic evaluation, with the consequences of treatment being measured in terms of quality-adjusted life years (QALYs), these community preference weights are typically used for calculating QALYs (Drummond et al., 1997, Gold et al., 1996).

Currently, the EuroQol Group has ratified 60 official language versions of EQ-5D, including German (Schulenburg von der et al., 1998). The validity of the EQ-5D has been shown for various diseases as well as for the general population (http://www.euroqol.org). Being a short and easy to administer questionnaire, the EQ-5D seems to be an attractive instrument to use for assessing quality of life and performing cost–utility analysis in a group of individuals with alcohol use disorders.

To our knowledge, the EQ-5D has been used only once in subjects with alcohol use disorders (Foster et al., 2002). This study reported that the HRQOL of alcohol dependent current drinkers was extremely poor compared to the general population. Another key finding was that clinicians’ preference based ratings of HRQOL tended to be much lower than patients’ ratings. However, the EQ-5D has not been explicitly tested for measurement properties in individuals with alcohol use disorders.

This study desires to analyze the acceptance/understanding and the discriminative ability of the EQ-5D in individuals with alcohol dependence. Acceptance/understanding describes the individuals’ ability to adequately complete the EQ-5D, and discriminative ability refers to the ability of the EQ-5D to distinguish among meaningful differences in individuals’ health status according to the impact of alcohol use disorders on HRQOL. Moreover, we analyzed the relationship of the EQ-5D with measures of quality of life, psychopathology and social functioning informing on aspects of EQ-5D validity. We analyzed, in detail, the relationships between the EQ-5D dimensions and theoretically related scales captured by measures of quality of life, psychopathology and social functioning.

Section snippets

Individuals

One hundred and three individuals with the main diagnosis of alcohol dependence according to the International Classification of Diseases (ICD-10 F10.2) (World Health Organization, 1992) were studied. All individuals showed evidence of tolerance and a strong sense of compulsion to consume alcohol. Moreover, they had difficulties controlling alcohol consumption, and at least one admission to a hospital was due to previous alcohol use disorders. All individuals were inpatients at least 18 years

Results

Table 2 presents the demographic and disease-related individual characteristics. Most patients were male with a mean age of 49 years. Twenty-eight percent of all individuals were married and about one-half lived alone. On an average, almost 8 years had passed since the first diagnosis of an alcohol use disorder, and individual's drinking behavior during a typical week before hospitalization resulted in an average alcohol consumption of 230.0 g per person per day (based on the classification of

Discussion

There seems to be good acceptance/understanding of the EQ-5D as indicated by a very high response rate compared to other self-assessed instruments. In accordance with a study examining the link between sleep, mood, alcohol consumption and HRQOL assessed by EQ-5D (Foster et al., 2002), we found that the most affected dimensions were “anxiety/depression” and “usual activities”. The proportion of confirmed expected relationships reflecting the similarity of several scales of utility, quality of

Acknowledgements

This study was funded by the German Statutory Health Insurance (grant number 932000-050) and the German Federal Ministry of Education and Research (grant number 01ZZ0106).

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