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

Objectives: To systematically identify and compare the concepts
contained in outcome measures of clinical trials on chronic
ischemic heart disease, diabetes mellitus, obesity and obstructive
pulmonary disease, including asthma using the International
Classification of Functioning, Disability and Health (ICF) as a
reference. Methods: Randomized controlled trials between 1993 and
2003 were located in MEDLINE and selected according predefined
criteria. The outcome measures were extracted and the concepts
contained in the outcome measures were linked by so called “linking
rules” to the ICF. Results: 166 trials on chronic ischemic heart
disease, 227 trials on diabetes mellitus, 428 trials on obesity and
253 trials on obstructive pulmonary disease were included. 10
different health status questionnaires were extracted in chronic
ischemic heart disease, 19 in diabetes mellitus, 47 in obesity, 39
in obstructive pulmonary disease. Across conditions at least 75%
(range: 75-92%) of the extracted concepts could be linked to the
ICF. In diabetes mellitus and obesity the most used ICF- categories
were ‘general metabolic functions’ (b540), in obstructive pulmonary
disease ‘respiratory functions’ (b440) and in chronic ischemic
heart disease ‘heart functions’ (b410). Conclusions: In all four
health conditions the majority of studies were drug trials focusing
on clinically relevant parameters and not on functioning. The ICF
provides a useful reference to identify and quantify the concepts
contained in outcome measures used in clinical trials.