Clinical evaluation is a multifactorial process producing as many clinical scores as there are clinical dimensions. For a medicoeconomical analysis however, a single global score would be most useful. The aim of this work was to examine methods allowing relative quantification of items on multidimensional clinical scores in order to determine an appropriate solution for weighted items aggregation.
Several techniques for item weighting, developed as part of a multi-criteria decision-making tool (AMCD Aide Multi-Critère à la Décision), were examined. Two methods were applied to multidimensional assessment of disability in order to estimate the weight that should be assigned to each of its six items before aggregation in a unique score. The AHP method was used with an interview of 20 functional rehabilitation specialists. The Diakoulaki method was based on the observation of thirty patients with chronic back pain and in thirty patients with vascular hemiplegia.
The three weighting schemes were very different from the uniform weighting and were not correlated with each other. The items best weighted by the AHP method were "physical independence" and "mobility". For the Diakoulaki method, they were "social integration" and "economic independence" for the chronic back pain patients, and "awareness of the outside world" and "economic independence" for the vascular hemiplegia patients. Application of these three weighting schemes to theoretical patients produced very different assessments of global disability.
Weighting schemes are useful to quantify the relative importance of individual clinical items. The choice of the weighting method is determinant and depends on the objective of the investigator. If the objective is a global score, the first step is to estimate the weight of the individual items, either when applying a validation process for a new multidimensional clinical score, or secondarily to adapt a validated score to a particular protocol.