Identifying the concepts contained in outcome measures of clinical trials on depressive disorders using the international classification of functioning, disability and health as a reference

Objectives: First, to systematically identify the concepts contained in outcome measures of trials on depressive disorders using the International Classification of Functioning, Disability and Health (ICF) as a reference. Secondly, to explore differences in the use of ICF categories across different intervention types. Thirdly, to examine which and how often health status measures have been applied in trials on depressive disorders. Methods: Randomized controlled trials between 1991 and 2000 were located in MEDLINE and selected according to predefined criteria. The outcome measures were extracted and the concepts contained in the outcome measures were linked to the ICF. Results: A random sample of 203 (50%) of 406 eligible studies were included. The 5 most used ICF categories (range 88-94%) were sleep functions (b134), emotional functions (b152), energy and drive functions (b130), thought functions (b160) and higher-level cognitive functions (b164), all belonging to the body functions component. The use of ICF categories did not vary across different intervention types. A total of 126 different health status measures were extracted. The Hamilton Rating Scale for Depression was the most used health status measure applied in 80% of the studies. Conclusion: Concepts about execution of tasks/actions, participation in life situations, and the influence of the environment were under-represented in the outcome assessment of trials on depressive disorders. These observations indicate that most trials were limited in their ability to assess more global individual outcomes.