An application of the thresholds of change model to the analysis of mental health data.
The threshold of change model (TCM) is a statistical technique for analyzing ordered stages of change variables. TCM focuses on the thresholds that separate the ordered stages, and the effects of explanatory variables are evaluated in terms of raising or lowering the thresholds. TCM also allows the explanatory variables to exert differential influence on each threshold. In this paper, we use TCM to analyze the data from a clinical trial that compared assertive community treatment (ACT) with standard case management (SCM) for patients with co-occurring severe mental illness and substance use disorder. Endpoint data (36-month follow up) were used for this analysis. The response variable is the recoded Substance Abuse Treatment Scale with three ordered levels (engagement/persuasion, active treatment, and recovery/relapse prevention), and hence two thresholds. The explanatory variables are gender and group (ACT vs. SCM). The results indicate that gender exerts constant and significant effects on both thresholds. The group effect is somewhat mixed: ACT lowers the first threshold (active treatment), but raises the second threshold (recovery/relapse prevention).
Dartmouth Medical School, Lebanon, New Hampshire, USA. haiyi.xie@dartmouth.edu
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D000293:Adolescent; D000328:Adult; D019090:Case Management / Q000592:standards*; D003155:Community Mental Health Centers / Q000592:standards*; D005260:Female; D006801:Humans; D008297:Male; D008603:Mental Health; D008875:Middle Aged; D008960:Models, Psychological; D009513:New Hampshire; D016017:Odds Ratio; D015397:Program Evaluation; D011618:Psychotic Disorders / Q000523:psychology* / Q000534:rehabilitation; D011788:Quality of Life; D019966:Substance-Related Disorders / Q000523:psychology* / Q000534:rehabilitation