Objectives: The Work Productivity and Activity Impairment Questionnaire (WPAI) is an instrument that measures work impairment in the setting of different diseases. One previous study validating the WPAI in Crohn's disease (CD) patients suggested that its reproducibility may be unsatisfactory. This study evaluated the validity and reproducibility of the Spain Spanish version of the WPAI questionnaire in CD patients.
Methods: In a prospective study, convergent validity was tested comparing WPAI with quality of life and CD activity indices. Known-groups validity was assessed by comparing WPAI scores in CD patients with active versus inactive disease. Reproducibility of repeated tests was evaluated by comparing two WPAI measures obtained two to four weeks apart in stable patients.
Results: One hundred eight patients were included in the various steps of the analysis. The WPAI showed adequate known groups validity and convergent validity. The reproducibility of the test and, specifically, that of the evaluation of presenteeism (the impairment of productivity while working) were good.
Conclusions: This study confirms the validity of WPAI for measuring work impairment in CD patients. In contrast to previous studies, the test reproducibility was adequate.
Copyright © 2011 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.