Development and validation of a quality of life instrument for patients with drug dependence: Comparisons with SF-36 and WHOQOL-100

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Abstract

Aim

Our goal was to develop a self-administered quality of life scale for patients with drug addiction/dependence (QOL-DA) and compare it with the SF-36 and the WHOQOL-100.

Methods

Employing theory and methodology of rating scale construction, a self-administered quality of life instrument for individuals with drug dependence QOL-DA was developed and evaluated utilizing responses from 212 drug-dependent subjects at the Kunming Municipal Mandatory Detoxification and Rehabilitation Center in China. Quality of life was measured using the SF-36, WHOQOL-100 and QOL-DA three times during the detoxification.

Results

Test–retest reliability in the domains of physical function, psychological function, social function and toxicity were 0.82, 0.64, 0.78, and 0.76, respectively. Cronbach's coefficient α for the 4 domains was 0.87, 0.89, 0.93 and 0.86, respectively. Correlations and factor analysis showed good construct validity. Criterion-related and convergent validity was confirmed by using the SF-36 and the WHOQOL-100 simultaneously. The instrument does show the change in QOL after two weeks of detoxification with higher standardized response mean higher than that of SF-36 and WHOQOL-100.

Conclusion

The instrument developed has good validity, reliability and better responsiveness than instruments currently used, and can be employed effectively to measure the quality of life of individuals with drug dependence.

Introduction

In the last 30 years, the research on quality of life (QOL) as well as health related quality of life (HRQOL) in the medical field has developed rapidly and has gained international attention. The assessment of quality of life has been applied as a significant outcome indicator in patients and certain cohorts (such as the elderly) in the fields of clinical trials, public health, resource allocation and policymaking. (Cox et al., 1992). Measurements of quality of life have been broadly used to evaluate treatments for cancer and chronic diseases.

It is well known that drug abuse has become a serious social and health problem worldwide. In China, although drug dependency had been stamped out in the 1950s, it reappeared after China's economic reforms and opening-up to the world. The number of registered drug users increased from 70,000 in 1990 to 1.16 million at the end of 2005, with three major characteristics or trends: lower age, higher proportion of intravenous injection, and higher proportion of heroin use. In the past decade, this has also become evident in rural areas, especially in the northwest and central regions of the country, where 72.7% of Chinese counties (cities or districts) reported problems with drug usage (Lu et al., 2008).

Studies on quality of life have recently started to look at drug dependency beyond the presence and severity of addiction symptoms and the side effects of treatments by examining how drug-addicted patients perceive and experience the repercussions on their daily life (Revicki et al., 2000, Zubaran and Foresti, 2009). Several studies involving quality of life in the field of drug dependence have been reported (Donovan et al., 2005, De Maeyer et al., 2010). Donovan et al. (2005) reviewed research on quality of life as an outcome measure in alcoholism treatment and found that thirty-six studies, published between 1993 and 2004, used the term “quality of life” to describe a status or outcome for individuals diagnosed with or being treated for alcohol abuse. In total, twelve different QOL measures were reported in these studies. Alcoholics had lower levels of QOL when compared with the general population norm or when compared with subjects with other chronic health problems. This relationship appeared to be moderated by a number of socio-demographic and client characteristics, such as age, education, gender and co-occurring psychiatric disorders. Puigdollers et al. (2004) studied quality of life of heroin users entering methadone maintenance treatment; Fassino et al. (2004) carried out a study on quality of life and personality disorders in heroin abusers.

Recently, De Maeyer et al. (2010) summarized and differentiated the available information on QOL in opiate-dependent individuals, finding that these individuals reported a lower (HR)QOL when compared with the general population and with people who had various medical illnesses. Most of the studies used generic measures of QOL assessments given the lack of specific instruments for drug dependency: da Silva Lima et al. (2005) used the World Health Organization Instrument (WHOQOL-BREF) and the Medical Outcomes study Short-forms SF-36, Daeppen et al. (1998) used the SF-36, and Foster et al. (2000) used the General Health Questionnaire (GHQ-12) and the Nottingham Health Profile (NHP). These instruments measure common issues of QOL but lack the sensitivity to evaluate treatments for drug dependency.

To our knowledge, only two specific drug dependency instruments: injection drug use quality of life scale (IDUQOL) and health-related quality of life test in drug abusers (HRQOLDA) have been reported (Hubley et al., 2005, Hubley et al., 2007, Lozano Rojas et al., 2009). The IDUQOL scale, using a 7-point Likert-type scale ranging from 1 (very dissatisfied) to 7 (very satisfied), was designed to capture the unique and individual circumstances that determine quality of life among injection drug users. It consists of 21 items of different life domains including drugs, drug treatment, harm reduction, education, and neighborhood safety. The 20 item HRQOLDA was developed as a measure of the effects of drug abuse on physical perception, psychological health, and social functioning, which was based on the bi-axial concept of addiction and an operational definition specific to drug abusers. The former focuses on injection drug users; the latter needs further validation in practice.

Therefore it is critical and timely to develop specific QOL instruments for individuals with a drug dependency. In China, no research on the development of a specific QOL instrument for individuals with a drug dependency has been reported to date. In this paper, we report the procedures, results and applications of the Quality Of Life for Individuals with drug dependence (QOL-DA), an instrument we developed to meet this important need.

Section snippets

Methods

Based on WHO's QOL concept and special issues related to drug addiction, this scale, Quality Of Life for Individuals with Drug Addiction/Dependence (QOL-DA), was designed to measure HRQOL for those with a drug (mainly heroin) addiction dependency so that it could be used to evaluate the different methods or modes of detoxification in terms of QOL. According to WHO, quality of life is defined as individuals’ perceptions of their position in life in the context of the culture and value systems in

Results

Table 2 presents details about the socio-demographic characteristics and drug usage history of the study samples, with a mean age of 26.7 (±5.3) and an age range of 16.4–45.8 years old for sample 1, and a mean age of 24.8 (±4.0) and an age range of 16.4–33.9 years old for sample 2.

Discussion

In this paper, we have discussed the development of a specific QOL (focused on HRQOL) instrument for individuals with a drug dependency based on WHO's definition of QOL (The WHOQOL Group, 1998). Although the physical domain of some generic QOL instruments might cover the items related to symptom/toxicity, it is worthwhile to treat symptom/toxicity as an additional domain to facilitate evaluating the special characteristics of detoxification when the effect of intervention is emphasized.

In

Acknowledgements

In carrying out this research project, we have received substantial assistance from staff at Kunming Municipal Mandatory Detoxification and Rehabilitation Center, Yunnan Province, and medical students at School of Public Health, Kunming Medical University. We sincerely appreciate their kind help.
Conflict of interest: None declared.
Funding: Supported by the National Natural Science Foundation of China (30360092, 30860248). This work was supported in part by a NIH grant 1 UL1 RR024160-01 when it

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