The prevalence of obesity is currently estimated at about 300 million people worldwide and is continuing to rise. Therefore, obesity is increasingly becoming a significant cause of disability and appears to lessen life expectancy markedly. From a societal perspective, obesity is associated with a decreased quality of life and increased healthcare costs. Based on our current understanding of obesity as a complex, multifactor condition with interactions between genetic, metabolic, environmental and personal factors, a patient-centred approach is critical for effective treatment, to measure the burden of disease and to evaluate treatment outcomes. Research has underlined the importance of measuring health status of obese patients and suggest the application of both, generic and condition-specific measures. However, no systematic framework that covers the spectrum of symptoms and problems in functioning of persons with obesity had been established at the time.

To tackle this issue, the ICF Research Branch and the World Health Organisation (WHO) with the scientific support of University Hospital of Berne (Switzerland), Parnassia Psychomedical Centre (The Netherlands), Ludwig-Maximilian University (Germany), Swiss Association of Physiotherapy (Switzerland), Obesity Institute/MedStar Research Institute (USA) and Hannover Medical School (Germany), initiated a project to develop internationally-accepted and evidence-based ICF Core Sets for obesity. 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 1993-2003 involving patients with obesity.
• The international expert survey (via email) using the Delphi technique was conducted with 24 health professionals, experts on the treatment of persons with obesity, to identify the set of domains that best describe the prototypical spectrum of problems in functioning and health in persons with obesity from the of health professional perspective.
• The multicentre cross-sectional study using the ICF checklist with a convenient sample of 52 patients undergoing inpatient or outpatient rehabilitation was performed to identify the common problems experienced by persons with obesity.

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 obesity. Twenty-one experts from 8 different countries decided which ICF categories are to be included in the ICF Core Sets for obesity following a formal, decision-making and consensus process which integrated the results from the 3 preparatory studies.

109 ICF categories were selected for inclusion in the Comprehensive ICF Core for obesity. These categories can be taken into account when conducting a comprehensive, multidisciplinary assessment. Out of the 109 Comprehensive ICF Core Set categories, 8 second-level ICF categories were selected for the Brief ICF Core for obesity. The Brief ICF Core Set can be used in assessing patients participating in a clinical study on obesity.

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

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