There is no consensus, however, on the issue of waiting lists. As discussed later in this paper, some experts in the drug abuse field contend that current waiting lists do not represent unmet demand for drug abuse treatment but rather poor referral mechanisms among currently operating drug abuse treatment programs. Other experts contend that current waiting lists greatly underestimate the unmet demand for treatment. Still others concede that waiting lists exist but nonetheless argue that treatment programs should not be expanded to the point where waiting lists would not occur.
This paper examines the empirical literature and expert opinions on waiting lists for drug abuse treatment and critiques the concept of waiting lists as a measure of unmet demand for treatment. Data from the early 1970s, when waiting lists for drug abuse treatment were also used as a measure of unmet treatment demand (U.S. House of Representatives, 1972), are included to provide some historical perspective. The limited data on the relationship between the waiting experience and subsequent client experience in drug abuse treatment are also reviewed. Finally, some unpublished data on the behavior of persons while on waiting lists are presented.
The development of techniques such as meta-analysis has greatly increased the analytic power of reviews of the scientific literature. Unfortunately, such techniques are not appropriate for examining the literature on waiting lists for drug abuse treatment. First, the number of studies addressing this issue is quite small. As one research group interested in the topic noted, "In spite of the increasing reports of the need to employ waiting lists, and their significance for the user and the treatment program, there is a virtual absence of research in this area, with the exception of those studies using waiting list controls" (Brown et al., 1989). Fewer than 15 studies were found through computerized literature searches in the MEDLARS, DIALOG, and PsychINFO 4 data bases with "waiting list" as a keyword. Most of the studies appeared in at least two of these three data bases, suggesting considerable overlap among them; such duplication also implied that additional computer searching was not likely to lead to many other articles or books. Interestingly, neither of the two most recent studies of the number of persons on waiting lists throughout the country was in these computerized literature data bases.
Many of the studies in the data bases were not relevant to this paper. A number of them recruited research subjects from among persons already enrolled in drug abuse treatment and then randomly assigned them to immediate