detailed assessments of clients in treatment. Among these advances has been the development of instruments that reliably assess drug abuse and dependence and co-occurring psychiatric disorders according to the criteria of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV; APA, 1994) and the International Classification of Diseases (ICD-10; WHO, 1992). Some of the most commonly used instruments are the Composite International Diagnostic Interview (CIDI); the Substance Abuse Module of the CIDI (the CIDI-SAM); the Diagnostic Interview Schedule (DIS); and the Structured Clinical Interview for DSM-IV (SCID). Work is currently under way to modify them to improve the distinctions between primary psychiatric disorders and drug-produced psychiatric syndromes in order to further improve treatment (D. Hasin, 1995 New York State Psychiatric Institute, personal communication).
Other instruments have been developed to assess the severity of patients' problems and their need for treatment across a wider range of areas. Among these, the most widely used is the Addiction Severity Index (ASI), which was developed in the early 1980s with research funds from both NIDA and the Department of Veterans Affairs (VA). ASI measures the degree of impairment and the need for treatment in each of seven areas commonly affected by drug abuse: drug and alcohol use, medical, family or social, employment, legal, and psychiatric (McLellan et al., 1980). The ASI has been found to be reliable and applicable within a wide range of settings, provided that appropriate training has been given to those who administer it. Unlike CIDI, DIS, and SCID, ASI does not make diagnoses but rather quantifies the degree to which impairment exists (and treatment is needed) in each of the seven areas. It is often used in clinical practice for evaluation and treatment planning.
One immediate positive effect of newer assessment techniques is the development of improved descriptions of patients. A very consistent finding, from a large number of studies using one or more of these assessment measures, is that the patient population is often engaged in polydrug use (i.e., use of a variety of illicit drugs and alcohol) and has other serious current or past problems in addition to drug abuse (e.g., psychiatric, employment, family/social problems) (Rounsaville et al., 1982; McLellan et al., 1994). These findings have been useful in developing treatment matching strategies (discussed below).
Advances in diagnosis have also led to comprehensive and accurate methods for assessing outcomes. The ASI has been particularly useful because it can measure degrees of improvement when administered on repeated occasions before, during, and after treatment. In treatment outcome studies, the ASI is usually supplemented with other measures such as urinalysis, breath alcohol tests, structured interviews for assessing psy-