Lower versus higher frequency of sessions in starting outpatient mental health care and the risk of a chronic course; a naturalistic cohort study

Bea Tiemens, Margot Kloos, Jan Spijker, Theo Ingenhoven, Mirjam Kampman, Gert-Jan Hendriks

An adequate frequency of treatment might be a prerequisite for a favorable outcome. Unfortunately, there is a diversity of factors that interfere with an adequate frequency of sessions. This occurs especially in the first phase of treatment, while the first phase seems vital for the rest of treatment. The aim of this naturalistic study was to explore the impact of the initial frequency of treatment sessions on treatment outcome in a diverse mental health care population. Anonymized data were analyzed from 2,634 patients allocated for anxiety disorders, depressive disorders, and personality disorders to outpatient treatment programs in a large general mental health care facility. Patients' treatment outcome was routinely monitored with the Outcome Questionnaire-45 (OQ-45.2), every 12 weeks. Frequency of sessions was assessed for the first three months of treatment. Using Cox-proportional-hazard models, we explored the associations between initial frequency and improvement (reliable significant change) and recovery (reliable and clinically significant change). Improvement and recovery were associated with symptom severity and functional impairment at start of treatment, the year the treatment started, number of measurements, the treatment program (anxiety disorders, depressive disorders, and personality disorders) and receiving group therapy other than psychotherapy. In all diagnostic groups, both improvement and recovery were associated with a higher frequency of sessions during the first three months of treatment. For improvement, this effect diminished after three years in treatment; however, for recovery this association was sustained. In addition to severity at start of treatment and other predictors of outcome, a low frequency of initial treatment sessions might lead to a less favorable outcome and a more chronic course of the mental disorder. This association seems not to be limited to a specific diagnostic group, but was found in a large group of patients with common mental disorders (depression and anxiety disorders) and patients with a personality disorder. Despite organizational obstacles, more effort should be made to start treatment quickly by an effective frequency of session.