Sensitivity of Preference-Weighted Health-Related Quality of Life Measures and Substance Use Severity
- Presenter:
Chair: William S. Cartwright; Discussant: Kathryn McCollister Mon June 5, 2006 13:45-15:15 Room 326
Cost-effectiveness analyses using generic preference-weighted health-related quality of life (PWHRQL) measures to calculate cost per quality-adjusted life year (QALY) ratios are useful for making decisions about how to most efficiently allocate limited healthcare resources. To date, cost per QALY analyses have not been widely reported for substance abuse interventions, however. One of the first steps towards supporting the validity of cost per QALY analyses for substance use disorder interventions is examining the relationship between substance use severity and PWHRQL. We will present data on this relationship for subjects referred to substance abuse treatment programs in Ohio. The generic PWHRQL measures used in this study include the self-administered Quality of Well-Being (QWB-SA) scale (originally designed for use in cost per QALY analyses) and the standard gamble-weighted Medical Outcomes Study SF-12 (SF-12 SG). The substance use severity measure was the Addictions Severity Index (ASI). Three groups of patients were identified: substance abuse, drug dependence only, and alcohol and drug dependence. Our current sample includes 238 subjects and we expect to add approximately one hundred additional subjects by the time of presentation. Using the N=238 sample, we found significant QWB-SA, SF-12 SG, and ASI subscale differences between the substance dependent and substance abuse groups (p<0.01). The QWB-SA and SF-12 SG scores for the substance dependent groups were similar to those found among chronic physical health disorders. In multivariate analyses predicting the PWHRQL measures and controlling for sociodemographic variables; the ASI medical, psychiatric, and drug use subscales were significant predictors of the QWB-SA (R2=32%) and these predictors plus the ASI family/social subscale were significant predictors of the SF-12 SG (R2=48%). We will also present results of the effect of substance dependence related to specific substances in the presentation. Based on our current findings, it appears that both the QWB-SA and SF-12 SG are sensitive to cross-sectional substance use severity in a treatment-referred sample. Ultimately, cost per QALY analyses can provide an additional metric for communicating the value of substance abuse interventions and will allow for the direct comparison with existing cost per QALY ratios for other physical and mental health interventions.
