Short Communication The influence of co-occurring axis I disorders on treatment utilization and outcome in homeless patients with substance use disorders Julia Austin ⁎, John D. McKellar, Rudolf Moos Center for Healthcare Evaluation, Health Services Research and Development Service, Department of Veterans Affairs Health Care System, Stanford University School of Medicine, VA Palo Alto Health Care System 3801 Miranda Ave. (MPD-152) Palo Alto, CA 94304, United States abstract article info Keywords: Homeless Co-occurring disorders Substance use Alcohol Treatment utilization The current study examined the relationship between co-occurring substance use and Axis I psychiatric disorders and treatment utilization and outcome among homeless individuals (N = 365) who participated in an episode of intensive outpatient substance use treatment. Compared to patients without a co-occurring diagnosis, homeless patients with a diagnosis of major depressive disorder or PTSD participated in more substance use treatment. Diagnostic status did not predict 12-month alcohol or drug treatment outcome. Substance use treatment programs appear to successfully engage homeless individuals with major depressive disorder and PTSD in treatment. Such individuals appear to achieve similar benefits from standard substance use treatment as do homeless individuals without such disorders. © 2011 Elsevier Ltd. All rights reserved. 1. Introduction Alcohol and drug dependence are the most common psychiatric diagnoses experienced by homeless individuals (Fazel, Khosla, Doll, & Geddes, 2008). Many homeless individuals meet criteria for other psychiatric diagnoses, including mood (Folsom et al., 2005) and psychotic (Fazel et al., 2008) disorders and have been exposed to trauma, a risk factor for PTSD (Buhrich, Hodder, & Teesson, 2000; Sacks, McKendrick, & Banks, 2008). Although precise epidemiological research is lacking, several studies have highlighted the unique mental health and treatment needs of homeless individuals with substance use disorders (SUDs); (Dietz, 2007; McNamara, Schumacher, Milby, Wallace, & Usdan, 2001; Savage & Lindsell, 2008). There is evidence that homeless adults with SUDs reduce substance use during treatment e.g., (Drake, Yovetich, Bebout, Harris, & McHugo, 1997; Smith, Meyers, & Delaney, 1998), but it is less clear whether homeless individuals with co-occurring Axis I psychiatric disorders do as well as those without such disorders in terms of substance use treatment utilization and outcome in non-integrated (standard) substance use treatment programs. Given the debate about the need for standard versus integrated SUD care for individuals with co-occurring psychiatric disorders (Flynn & Brown, 2008; Tiet & Mausbach, 2007), it is important to learn more about the relationship between co-occurring disorder status and treatment utilization and outcome. Prior findings are mixed, with some studies indicating that individuals with co-occurring disorders have poorer SUD treatment outcomes e.g., (Rounsaville, Dolinsky, Babor, & Meyer, 1987) and some indicating equal or better SUD outcomes e.g., (Boden & Moos, 2009; Charney, Paraherakis, Negrete, & Gill, 1998; Mann, Hintz, & Jung, 2004; Tiet & Mausbach, 2007). Very few studies have examined these issues in homeless popula- tions. According to Justus et al. (2006), homeless patients with a SUD and depression diagnosis were more likely to complete domiciliary care than those without a depression diagnosis. In terms of treatment outcome, McNamara et al. (2001) found that homeless individuals with SUD and co-occurring Axis I psychiatric disorders achieved substance use outcomes in contingency management treatment that were as good as those without Axis I diagnoses. Similarly, Burns et al. (2010) found that homeless individuals who were dependent on cocaine and had co- morbid PTSD did as well on substance use outcomes in a contingency management program as comparable individuals without PTSD. Thus, homeless patients with co-occurring SUD and psychiatric disorders do not necessarily participate less in substance use treatment or have poorer outcome than those without psychiatric disorders. However, only one prior study of homeless patients has examined treatment utilization. Moreover, prior work has not compared patients with different co-occurring Axis I disorders and has mainly considered outcome following a highly structured treatment (contingency man- agement); (McGovern, Fox, Xie, & Drake, 2004). In addition, with one exception (Gonzalez & Rosenheck, 2002), it is not known whether homeless individuals with co-occurring disorders who participate in more treatment demonstrate improved substance use outcomes. To address these issues, we examined whether co-occurring disorder status predicted treatment utilization and outcome among homeless patients who participated in intensive outpatient substance use treatment. Addictive Behaviors 36 (2011) 941–944 ⁎ Corresponding author at: University of New Mexico, MSC03 2220, Albuquerque, NM 87131, United States. Tel.: +1 505 843 6375. E-mail address: jlaustin@unm.edu (J. Austin). 0306-4603/$ – see front matter © 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.addbeh.2011.05.001 Contents lists available at ScienceDirect Addictive Behaviors