Longitudinal association of preference-weighted health-related quality of life measures and substance use disorder outcomes

Aim To examine the construct validity of generic preference-weighted health-related quality of life measures in a sample of patients with a substance use disorder (SUD). Design Longitudinal (baseline and 6-month follow-up) data from a research study that evaluated interventions to improve linkage and engagement with SUD treatment. Setting A central intake unit that referred patients to seven SUD treatment centers in a Midwestern US metropolitan area. Participants A total of 495 individuals with a SUD. Measurements Participants completed two preference-weighted measures: the self-administered Quality of Well-Being scale (QWB-SA) and the standard gamble weighted Medical Outcomes Study SF-12 (SF-6D). They were also administered two clinical assessments: all seven domains of the Addiction Severity Index (ASI) and a symptom checklist based on the DSM-IV. Construct validity was determined via the relationships between disease-specific SUD and generic measures. Findings In unadjusted analyses, the QWB-SA and SF-6D change scores were correlated significantly with six ASI subscale change scores, but not with employment status. In adjusted repeated-measures analyses, three of seven ASI subscale scores were significant predictors of QWB-SA and 5/7 ASI subscale scores were significant predictors of SF-6D. Abstinence and problematic use at follow-up were significant predictors of QWB-SA and SF-6D. Effect sizes ranged from 0.352 to 0.400 for abstinence and -0.484 to -0.585 for problematic use. Conclusions Generic preference-weighted health-related quality of life measures show moderate to good associations with substance-use specific measures and in certain circumstances can be used in their stead. This study provides further support for the use of the Quality of Well-Being scale and Medical Outcomes Study SF-12 in clinical and economic evaluations of substance use disorder interventions.