When compared to other health interventions, all of the substance abuse treatment modalities examined appear to be cost-effective (Laupacis et al. 1992
). The outpatient drug-free treatment modality, however, appears to be most cost-effective, even for clients who are more likely to choose (or be referred to) treatment in other modalities. While variations in settings, modalities, and outcomes make comparisons of cost-effectiveness estimates across studies difficult, our findings are, in general, consistent with the results of most prior cost-effectiveness studies of alcohol and substance abused treatment. Those studies also found that the less intensive treatment modalities, such as the outpatient drug-free modality, are more cost-effective than the more intensive ones (Longabaugh et al. 1983
; Pettinati et al. 1999
; Annis 1986
; French 1995
One exception is the cost-benefit analysis of the TOPS study which found that residential treatments had a higher benefit to cost ratio than other programs (Hubbard et al. 1989
). The benefit estimates in that study, however, were based on reduced costs of criminal activities, making residential treatment, which reduces the opportunities for criminal activities, appear more attractive. This discrepancy between our findings and the results of the TOPS study highlight the variations in perspective and outcome domains in economic analyses of substance abuse treatment programs. While abstinence and reduction in substance use are central measures for assessment of effectiveness of treatments, other outcomes such as reduction in criminal activity may be more important when examining the societal benefits of treatments in terms of averted costs of crime (Reuter 2001
Our findings have implications for current efforts to identify client characteristics that best predict successful outcome in one treatment setting versus another (McLellan et al. 1997
). We found no evidence that, at least as it occurs in usual treatment settings, selection into programs improves effectiveness or efficiency of treatments. This is in contrast to a previous study in an HMO that found improved effectiveness among clients who “self-selected” themselves into a day-hospital setting rather than an outpatient setting (Weisner et al. 2000
). This self-selected sample, however, was comprised of clients who were unable or unwilling to be randomized to the controlled trial arm of that study, raising questions about the representativeness of this sample population.
It is also noteworthy that attempts at client–problem matching in the past have produced mixed results (Pettinati et al. 1999
; Shepard, Larson, and Hoffman 1999
; McLellan et al. 1997
). Commenting on these studies, McLellan et al. (1997)
wrote, “This idea of ‘matching’ the right types of clients to the right kinds of programs has been as attractive to clinicians and administrators as it has been elusive to those who have tried to accomplish it” (p. 730). Furthermore, as these authors note, matching clients with treatments is often not feasible in the real world.
From our data, it is possible to derive a back-of-the-envelope estimate of the potential savings that would accrue had all individuals been treated in the most cost-effective treatment modality, that is, the outpatient drug-free modality. Using the sampling weights, the SROS sample represents about 950,000 clients who sought care in one of the four treatment modalities across the United States in the 12 months ending August 31, 1990. The cost of treatment in these settings amounted to approximately $2.4 billion based on our individualized cost data. Had all these individuals been treated in the outpatient drug-free modality (average cost of $1,204 per treated case), the overall cost of treatment would have amounted to only $1.1 billion—that is, a saving of more than 50 percent in the overall cost of treatment with no impact on overall treatment effectiveness!
We caution, however, about extrapolating from the SROS data to the present time. The mix and content of services has changed dramatically since the 1990s when SROS was conducted. The rate and length of inpatient treatments were reduced during this period and outpatient care replaced the more costly inpatient and residential care in many settings (Mark et al. 2000
; Chen, Wagner, and Barnett 2001
). Nevertheless, a 1999 survey of substance abuse treatment facilities showed that 25 percent of facilities continue to offer residential rehabilitation (Substance Abuse and Mental Health Services Administration 2001
). This percentage was as high as 44 percent in some public settings. Furthermore, up to 28 percent of state facilities offered no outpatient rehabilitation programs. This may be, at least partly, attributable to the current payment systems that perversely encourage the provision of residential/inpatient care, even when it is not the clinically preferred modality (French 1995
). Clearly, more attention should be paid to creating incentives that encourage the use of more cost-effective interventions.
The findings of this study should be interpreted in the context of the limitations of the SROS data and our analyses. The SROS was not a randomized clinical trial. While stratification according to propensity scores controls for the effect of observed confounders, it does not necessarily control for the effect of unobserved
variables. Furthermore, only about 59 percent of the original SROS sample of 3,047 was followed-up. Rates of follow-up, however, were similar across modalities, and in analyses conducted by the SROS investigators, few baseline characteristics predicted loss to follow-up (Substance Abuse and Mental Health Services Administration 1998
Assessment of outcomes was based on self-reports of the clients about behaviors in the distant past and was thus open to memory distortion and bias. To assess the validity of self-reports, SROS investigators conducted urinalysis for 76 percent of the sample interviewed in 1995–1996. Agreement between self-report and urinalysis ranged from 89.7 percent to 98.5 percent for drug use in the past week and from 86.2 percent to 99.0 percent in the past 24 hours. In addition, the SROS investigators tried to improve the reliability of self-reports of past events by various methods such as using color-coded calendars and interview techniques that facilitate discussion of sensitive subjects. We also note that outcomes defined for the present study (abstinence and any reduction in use) may be less prone to memory distortion than the actual number of days of use.
Lastly, our analyses were limited to the index treatment episode. Many clients continue treatment after discharge from a treatment episode and there is evidence that continuity of care may be associated with better outcomes (e.g., Ritsher, Moos, and Finney 2002
). Also, a more complete picture of treatment costs should incorporate all treatments following the index treatment episode. Unfortunately, the SROS data do not provide information on the timing and the cost of treatment encounters following the index treatment episode.
In summary, this article demonstrated that, after adjusting for case-mix, various modalities of substance disorder treatment are more or less similarly effective. While all programs appear to be cost-effective, the outpatient drug-free modality is consistently the most cost-effective. Motivated by cost-containment, many health care systems are already shifting from the inpatient programs to the less costly outpatient programs. Nevertheless, it is of concern that the savings in the cost of care for individual clients are not matched by investments for extending services to a larger group of potential clients who are in need of such treatment (Chen, Wagner, and Barnett 2001
; Galanter et al. 2000
). The Office of National Drug Control Policy estimated that in 1996, only about 2 million of the 4.4–5.3 million Americans in need of treatment for substance abuse received such treatment (Mark et al. 2000
). Savings from improved efficiency of current treatments for substance disorders may provide some of the needed funds to extend care to those who currently do not receive any such care.