Exploring differential item functioning in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC).

ABSTRACT:

Background

The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) is a widely used patient reported outcome in osteoarthritis. An important, but frequently overlooked, aspect of validating health outcome measures is to establish if items exhibit differential item functioning (DIF). That is, if respondents have the same underlying level of an attribute, does the item give the same score in different subgroups or is it biased towards one subgroup or another. The aim of the study was to explore DIF in the Likert format WOMAC for the first time in a UK osteoarthritis population with respect to demographic, social, clinical and psychological factors.

Methods

The sample comprised a community sample of 763 people with osteoarthritis who participated in the Somer

SUBMITTER: Pollard B 

PROVIDER: S-EPMC3582585 | biostudies-literature | 2012 Dec

REPOSITORIES: biostudies-literature