Depression is associated with significant loss of quality of life, increased morbidity and mortality and enormous economic burden, the largest component of which derives from lost work productivity. Global Burden of Disease analysis shows that unipolar depressive disorders are ranked as the fourth leading cause of burden among all diseases. By 2020, the burden of depression is expected to increase to 5.7% of the total burden of disease, becoming the second leading cause of global disability-adjusted life years lost. Functioning is increasingly taken into account for the diagnoses of depression as well as for evaluating the effectiveness of treatments. The American Psychiatric Association included the concept of functioning as diagnostic option for assessing major depressive disorder in the 4th edition of its Diagnostic and Statistical Manual of Mental Disorders.

To tackle the issues related to assessing functioning in persons with depression (e.g. uncertainty about the relevant domains of functioning and how to measure them, existing measures vary quite considerably regarding the domains of functioning), the ICF Research Branch and the World Health Organisation (WHO) with the scientific support of Hospital Geral de Santo António (Portugal), University Hospital Vienna (Austria), Jefferson Medical College of Thomas Jefferson University (USA), Ludwig-Maximilian University (Germany) and Maastricht University (The Netherlands), initiated a project to develop internationally-accepted and evidence-based ICF Core Sets for depression, a practical tool that covers the spectrum of symptoms and limitations in functioning of persons with depression. This project was part of a larger project examining 12 chronic conditions with a high burden of disease.

The preparatory phase included a systematic literature review, a Delphi exercise and an empirical data collection using the ICF checklist:

• The systematic literature review was performed to identify and compare the concepts contained in outcome measures of randomized, controlled clinical trials published from 1991-2000 involving patients with depression.
• The international expert survey (via email) using the Delphi technique was conducted with 22 health professionals, experts on the treatment of persons with depression, to identify the set of domains that best describe the prototypical spectrum of problems in functioning and health in persons with depression from the of health professional perspective.
• The multicentre cross-sectional study using the ICF checklist with a convenient sample of 50 patients undergoing inpatient or outpatient rehabilitation was performed to identify the common problems experienced by persons with depression.

An international ICF consensus conference took place from 31 January to 3 February 2003 at a quiet monastery situated in a pleasant landscape far from any city and distractions. The aim of the conference was to establish the Comprehensive and Brief ICF Core Sets for patients with depression. Twenty experts (psychiatrists, physicians with at least a specialization in physical and rehabilitation medicine, psychologists, physiotherapists, nurse and occupational therapist) from 8 different countries decided which ICF categories are to be included in the ICF Core Sets for depression following a formal, decision-making and consensus process which integrated the results from the 3 preparatory studies.

121 ICF categories were selected for inclusion in the Comprehensive ICF Core for depression. These categories can be taken into account when conducting a comprehensive, multidisciplinary assessment. Out of the 121 Comprehensive ICF Core Set categories, 31 ICF categories were selected as categories for the Brief ICF Core for depression. The Brief ICF Core Set can be used in assessing patients participating in a clinical study on depression.

For more information, feel free to contact the ICF Research Branch (melissa.selb@paranet.ch).

• Comprehensive & Brief ICF Core Sets for depression (download PDF)