How much therapy is enough? The dose-response effect and its moderators in a psychology training clinic

The current study aims to sharpen the understanding of the psychotherapy dose-response effect and its moderators in a psychology training clinic.

Data were extracted from 58 client records. Weekly Patient Health Questionnaire-9 and Generalized Anxiety Disorder-7, as well as Outcomes Questionnaire-45.2, administered every fifth session, assessed whether clients achieved reliable change (RC) and clinically significant and reliable change (CSR) during treatment. Survival analyses were conducted to determine the sessions required for 50% of the sample to achieve these outcomes. Multilevel Cox frailty regressions were used to investigate client-and-therapy-based moderators.

The median time for 50% of the sample to achieve RC was 8-10 sessions and 11 sessions to achieve initial CSR. Past treatment history was a significant moderator of time to achieve RC.

From a population perspective, psychotherapy is most beneficial to patients early in treatment. Sharper understanding of the number of sessions required to achieve meaningful change can inform practice in training settings.