Depression is a major cause of disability worldwide and effective management of this is a key challenge for health care systems.

The study, funded by the National Institute for Health Research (NIHR), confirmed evidence that 'low-intensity' interventions provide significant clinical benefit. Initial severity of depression is one of the key variables determining who gets 'low' or 'high' intensity treatment, but this is largely based on epidemiological studies and clinical experience rather than high quality evidence.

Researchers from an international collaboration carrid out a meta-analysis of several studies involving 2470 patients with depression, all treated in a non-hospital setting. All studies were from the year 2000 or later with a sample size of more than 50 patients. The mean age in all studies was 35-45, and studies included patients with lower levels of depressive symptoms, as well as those with quite severe depression.

'Low-intensity' treatment was defined as interventions designed to help patients manage depressive symptoms such as self-help books or interactive websites, often with limited guidance and support from a health professional. Self-help groups were excluded.

The researchers found that patients with more severe depression at baseline derive "at least as good clinical benefit from 'low-intensity' interventions as less severely ill patients." They recommend including 'low-intensity' interventions in the first step of treating severely ill patients and encouraging the majority of patients to use them as the initial treatment option.

Professor Peter Bower, from The University of Manchester who led the research, said: "To better manage depression in the community, many services seek to provide simple forms of psychological therapy (so called 'low intensity' interventions) to depressed patients. We assessed whether more severely ill patients demonstrated better or worse treatment effects from 'low-intensity' treatments. We found no clinically meaningful differences in treatment effects between more and less severely ill patients receiving 'low-intensity' interventions. Patients with more severe depression can be offered 'low-intensity' treatments as part of a stepped care model."

The researchers also say that an important research question for the future is whether low-intensity treatments are cost-effective and if "initial experience with low intensity interventions could act as a barrier to further treatment."