Predicting response to alcohol and drug abuse treatments. Role of psychiatric severity.

Male alcoholics (n = 460) and drug addicts (n = 282) were evaluated at six-month follow-up after treatment in six rehabilitation programs. Initial analyses of the unstratified samples showed significant patient improvement, but no evidence of differential effectiveness from different treatments or from "matching" patients to treatments. The two samples were then divided into groups based on the number, duration, and intensity of their psychiatric symptoms at admission, ie, their overall "psychiatric severity." Patients with low psychiatric severity improved in every treatment program. Patients with high psychiatric severity showed virtually no improvement in any treatment. Patients with midrange psychiatric severity (60% of the samples) showed outcome differences from different treatments and especially from specific patient-program matches. These findings support the effectiveness and specificity of different substance abuse treatments, suggest methodologic reasons for the lack of similar findings in previous studies, and demonstrate the importance of psychiatric factors in substance abuse treatment.