Clinical Textbook of Addictive Disorders 3rd ed - R. Frances, S. Miller, A. Mack (Guilford, 2005) WW

250 IV. SPECIAL POPULATIONSdisorder diagnoses is increased when comparing clinical to community samples,and the highest rates of comorbid mental disorders–SUDs are typically found ininstitutional populations, including psychiatric units, substance abuse programs,and jails and prisons (Hien, Zimberg, Weisman, First, & Ackerman,1997; Jordan, Schlenger, Fairbank, & Caddell, 1996; Kokkevi & Stefanis, 1995;Regier et al., 1990). This is due in part to the selection bias that those mostlikely admitted to treatment programs are people with impairment due to theirdrug use. Because of higher severity, they are at higher risk for an additionalsubstance use diagnosis than other drug users.Comorbidity of various substance use and other mental disorders tends tocluster among certain subsets of the general population, such that more thanhalf of the lifetime alcohol, drug, and mental disorders diagnoses can be foundamong about 14% of the population (Kessler et al., 1994). In any year, almost59% of the community sample with an alcohol, drug, or other mental (ADM)disorder meet criteria for three or more lifetime ADM disorders (Kessler et al.,1994). Therefore, compared to the community, treatment settings that aggregatethose with SUDs are also most likely to cohort people at the highest riskfor multiple SUDs. This is borne out in large-scale family genetics studies. Forexample, in the Collaborative Study on the Genetics of Alcoholism (COGA),among 1,212 subjects with definite alcohol dependence, recruited from addictiontreatment centers, 62% had an additional diagnosis of cannabis and/orcocaine dependence (Bierut et al., 1998).Treatment Episode Data Set (TEDS) data over the period 1992–2001 consistentlyrevealed that about half of treatment admissions have reported multipleSUDs (SAMHSA, 2003b). This means that in addition to the index substancefor which the patient was admitted to treatment, a substantial portion ofpatients are also abusing other substances. The SAMHSA-sponsored NationalSurvey of Substance Abuse Treatment Services (NSSATS) demonstrated thatof the 1,123,239 people receiving treatment in 13,720 responding facilities in2002, 48% were being treated for abuse or dependence on both alcohol and atleast one other substance (SAMHSA, 2003a). Thirty-one percent were intreatment for drug use disorders only, while the remaining 21% were in treatmentfor alcohol use disorders only. Similarly, data from the 2001 TEDSrevealed that 54% of all persons admitted to substance abuse treatmentreported multiple substance use, and approximately 42% of all admissionsreported problems with both alcohol and drugs (SAMHSA, 2003b). Alcoholand opiates were reported more often as primary substances than as secondarysubstances (TEDS; SAMHSA, 2003b). The most commonly reported secondarysubstances were alcohol, marijuana/hashish, and cocaine.Multiple Substance Use DisordersThe increased risk of comorbidity among treatment-seeking populations overthat of the general population has clinical implications for the outcome of treat-