Dose-effect relations and responsive regulation of treatment duration: the good enough level.

This study examined rates of improvement in psychotherapy as a function of the number of sessions attended. The clients (N=1,868; 73.1% female; 92.4% White; average age=40), who were seen for a variety of problems in routine primary care mental health practices, attended 1 to 12 sessions, had planned endings, and completed the Clinical Outcomes in Routine Evaluation-Outcome Measure (CORE-OM) at the beginning and end of their treatment. The percentage of clients achieving reliable and clinically significant improvement (RCSI) on the CORE-OM did not increase with number of sessions attended. Among clients who began treatment above the CORE-OM clinical cutoff (n=1,472), the RCSI rate ranged from 88% for clients who attended 1 session down to 62% for clients who attended 12 sessions (r=-.91). Previously reported negatively accelerating aggregate curves may reflect progressive ending of treatment by clients who had achieved a good enough level of improvement. Copyright (c) 2006 APA, all rights reserved.