WORK, CLASSROOM AND ACTIVITY IMPAIRMENT INSTRUMENTS - VALIDATION STUDIES IN ALLERGIC RHINITIS

The validity and responsiveness of allergy-specific questions in the f ormat of the Work Productivity and Activity Impairment (WPAI) question naire were tested, and the work, activity and classroom impairment of allergic rhinitis patients with moderate to severe allergy symptoms we re described. Allergy-specific WPAI (WPAI-AS) instruments were complet ed at baseline and at week 1 and week 2 by patient in 2 multicentre, d ouble-blind, randomised placebo-controlled clinical trials of antihist amines: terfenadine (work/activity impairment; n = 422) or fexofenadin e (MDL 16,455A) [classroom impairment; n = 241]. The validity, respons iveness to clinical change, and reproducibility in the absence of clin ical change of the WPAI-AS were measured independently by symptom seve rity scores. Allergy symptoms were associated with impairment at work, at other regular activities, and in the classroom. The studies establ ished the discriminative and evaluative validity, reproducibility and responsiveness of WPAI-AS measures of work impairment, overall work im pairment, activity impairment and classroom impairment secondary to al lergy symptoms, but not of work or classroom time missed. To detect a 5% difference in impairment, with 80% power and 5% type I error for a 2-sided hypothesis test (change from baseline to weeks 1 and 2 combine d) would require 201 patients/treatment group (overall work impairment ), and 192 patients/treatment group (overall classroom impairment). Th ese results validate the WPAI-AS as tools in quality-of-life analysis of allergic rhinitis and provide data for selecting an adequate sample size to differentiate interventions in controlled studies measuring c hanges in work, activity and classroom impairment secondary to allergi c rhinitis symptoms.