Purpose: Quality of life (QOL) has become an important endpoint in clinical trials and studies of medical interventions for many chronic diseases, but has not been widely studied in the substance abuse field. The purpose of this study was to measure QOL in a large sample of adult substance abusers (SA), to compare QOL ratings with those for other chronic diseases, and to assess factors influencing QOL levels in this population.
Methods: Hour-long personal interviews were administered to 570 randomly selected substance abuse clients in six detoxification centers and seven outpatient facilities in Massachusetts. Two QOL instruments--the Multidimensional Index of Life Quality (MILQ) and the SF-12--were used to measure QOL. Substance use problems were measured by the Addiction Severity Index Drug and Alcohol composite scores. QOL scores were compared to those for patients with other chronic diseases. Multivariable regression analysis was used to estimate the influence of demographic characteristics, co-morbidities, and substance use on QOL summary scores.
Results: SA clients reported significantly lower QOL scores than patients about to undergo heart surgery on seven of the nine MILQ domains as well as the MILQ QOL summary index. SA clients also had much lower mean scores than the general population on both the SF-12's Mental Health (ES = -1.80) and Physical Health (ES = -0.58) component scales. SF-12 physical component scores were similar to those for other chronic diseases, but mental component scores were markedly lower and comparable on average to clinically depressed groups. In the regression model, MILQ Index scores were significantly lower for dual diagnosis and detoxification cases. Index scores were negatively associated with ASI drug composite scores, but not with ASI alcohol scores.
Implications: The results of this study suggest that the physical functioning of adult substance abusers is similar to the levels for patients diagnosed with other serious chronic diseases, but that mental functioning is much lower. QOL provides information about functioning and well-being that is not captured by traditional measures of substance use, and may soon begin to play a more prominent role in evaluating the effectiveness of treatment services for substance abusers.