This study identifies longitudinal psychiatric trajectories of 934 adult individuals entering chemical dependency treatment in a private, managed care health plan and examines the relationship of these trajectories with substance use (SU) outcomes. The authors apply a group-based modeling approach to identify trajectory groups based on repeated measures of psychiatric severity for 9 years and identify four distinct groups. Results of multivariate logistic generalized estimating equation models find an association between psychiatric trajectories and long-term SU. Older cohorts and life course measures of marital status and employment status as individuals changed over time are related to drug and some alcohol outcomes.
Keywords longitudinal substance use outcomes; psychiatric trajectories; group-based modeling; managed care; adult chemical dependency patientsCo-occurring psychiatric and substance use (SU) conditions are a major clinical and policy concern (Havassy, Alvidrez, and Owen 2004;Helzer and Pryzbeck 1988;Kessler et al. 1996;Mertens et al. 2003;Timko, Dixon, and Moos 2005). Psychiatric conditions are highly prevalent among individuals with SU problems (Alaja et al. 1998;Harris and Edlund 2005;Kessler et al. 1996;Mendelson et al. 1986;Moos, Brennan, and Mertens 1994), and research has found that interventions directed at psychiatric problems during chemical dependency (CD) treatment lead to improved treatment outcomes (Chi, Satre, and Weisner 2006;McLellan et al. 1993;Ray, Weisner, and Mertens 2005;Saxon and Calsyn 1995). Psychiatric severity is also a well-established predictor of SU outcomes, quality of life, and subsequent health status (Charney et al. 2005;Friedmann et al. 2003;Moos, Nichol, and Moos 2002;Ray, Weisner, and Mertens 2005;Ritsher et al. 2002;Schaar and Ojehagen 2003).However, research on long-term mental health (MH) outcomes and their relationship with SU outcomes is sparse. An earlier study of the current sample measuring medical service use and cost for 5 years found that psychiatric and medical severity declined steeply in the immediate postintake period but remained stable thereafter, and that psychiatric and medical severity were consistently associated with higher inpatient and emergency room (ER) use over time (Parthasarathy and Weisner 2005). Another study examining cocaine-dependent men and women 5 years following treatment discharge also found reduced levels of psychological (Grella, Joshi, and Hser 2003). A 12-year follow-up study of psychiatric symptomatology among cocaine-dependent men in a Veterans Affairs program found that the Hopkins Symptom Checklist-58 scores for depression, anxiety, obsessivecompulsiveness, and interpersonal sensitivity showed continuous improvement from baseline to 12-year follow-up for those with 5 or more years of cocaine abstinence, whereas those with fewer years of abstinence showed improvement from baseline to 1 year but no significant change from 1 year to 12 years (Herbeck et al. 2006). The findings of these studies suggest an overall...