[Criteria for defining consensus achievement in Delphi studies that assess potentially inappropriate medications in...

The statistical analysis of survey responses based on a categorical Likert scale, as those used in the Delphi technique, has been questioned because the methodology used is based on numerical data analysis.

To develop criteria for defining the consensus achievement in Delphi studies conducted for the assessment of potentially inappropriate medications (PIM) in the elderly.

It was constructed an index (Yq) which takes into account the agreement by pairs of evaluators, whose calculus equation is based on combinatorial analysis. Yq was applied in a pilot study with Delphi methodology for assessing the safety of 12 drugs through a Likert scale with five response categories.

On the basis of analyzing the distance (d) in between each pair of categories from the scale, it was determined the associated weighting, w=1-d, to be applied in the calculus of Yq: proportion of agreements weighted. There were defined three criteria that need to be satisfied to obtained the consensus in each item (drug) of Delphi questionnaire : a) Number of evaluators ≥60% of the panel members, b)Yq≥0,800; c) frequency of the statistical mode ≥60%. On regards to the analysis, 8/12 drugs were evaluated as potentially inappropriate for elderly adults while the remaining 4 should be revalued in successive rounds due to not obtaining consensus.

The index takes into account the real distances between the Likert scale categories and the developed criteria constitute a simple tool for the analysis of the Delphi questionnaires made for the valuation of PIM on older adults.