Table 1

Phases of development for the ASAS Health Index

	Phase	Aims	Methods
Ia	Preparatory	Development of a pool of items representing the categories of the Comprehensive ICF Core Set for AS	Linkage of various assessment tools for functioning and health to ICF categories
Ib	Patient meeting	Patient preference and weighting of the items per ICF category	Relative weight to each item, patient-distributed 100 points per ICF category.
II	1st international cross-sectional survey	Item reduction (within and across ICF categories)	Rasch analysis, Spearman's rank correlation coefficient
III	Expert consultation	Agreement on item reduction	Nominal consensus process
IV	2nd international cross-sectional survey	Validation of the draft version and further item reduction	Testing psychometric properties Rasch analysis
V	Consensus Meeting	Agreement on a final version	Nominal consensus process

AS, ankylosing spondylitis; ASAS, Assessment of SpondyloArthritis international Society; ICF, International Classification of Functioning, Disability and Health.