OBJECTIVES: Indices such as the International Classification of Functioning, Disability and Health (ICF) are commonly used to measure outcomes for decision making. As with other instruments, equal weight is assigned to each item without distinguishing relevance. From the patient's perspective, the validity of the outcomes may be questioned. The aim is to examine the extent to which a preference-weighted assessment of core elements of the ICF differs from unweighted assessments currently used in clinical decision making.

METHODS: Three best-worst scaling experiments are used to assess ICF dimensions in terms of body function/movement, neglect/perception and activities. Stroke patients and citizens are recruited. The ICF "tariff" is created by converting the ICF generic percentage qualifiers for impairments into a unidimensional index. Preference weights for levels within each dimension are determined on a scale of 0 to 1, with the most desirable level rated 1.

RESULTS: N=1112 participants were recruited through August/September 2022. There is evidence of divergent validity of preference-weighted and unweighted scores for the ICF, based on the intraclass correlation coefficient. Unweighted scores in the dimensions of body function, activity, and neglect differ significantly from preference-weighted scores from BWS experiments in general (e.g., ICC_movement: 0.864, ICC_neglect: 0.491) and for various hypothetical health states constructed on the basis of ICF states.

CONCLUSIONS: Body functions have effects on activities, and these effect on health-related quality of life. This raises the question how the value is measured and considered in decision-making? The results reveal that ICF body functions or activities are not equally weighted by those affected.

This fosters discussions on the differences of preference-weighted scores and simple additive models to develop a patient-centered classification of impairments and therapy goals.

(The joint-project is funded by European Funds ESF, EFRE, ELER and the Ministery of Education, Science and Culture Mecklenburg-Vorpommern, Germany. Reference: ESF/14-BM-A55-0001/19-A01)