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

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.