Validity of the Workers Productivity and Activity Impairment Questionnaire: Specific Health Problem (WPAI:SHP) in patients with systemic sclerosis

Abstract

Objective. To evaluate the construct validity of the Workers Productivity and Impairment Activity Index: Specific Health Problem (WPAI:SHP) in Australian systemic sclerosis (SSc) patients. Methods. SSc patients, identified through the Australian Scleroderma Cohort Study database, completed the WPAI:SHP and a quality of life instrument (PROMIS-29) cross-sectionally. The construct validity of the WPAI:SHP was assessed by the correlations between the WPAI:SHP and a range of SSc health states. Non-parametric correlation, including Spearman's correlation (ρ), was used to test the validity of WPAI:SHP and ability to distinguish between different health states. Results. A total of 476 completed que..