Validity, reliability, and responsiveness of the work productivity and activity impairment questionnaire in Crohn's...

Crohn's disease (CD) is a chronic inflammatory bowel disease usually diagnosed in early adult life and characterized by unpredictable flares and debilitating symptoms such as diarrhea, abdominal pain, and fever, which can interfere with a patient's ability to work and perform daily activities.

The aim of this study was to assess the validity, reliability, and responsiveness of the Work Productivity and Activity Impairment questionnaire in CD (WPAI:CD).

The WPAI:CD was tested in CD patients enrolled in a 26-week randomized clinical trial of cer-tolizumab pegol versus placebo. Discriminative validity of WPAI:CD absenteeism, presenteeism(reduced on-the-job effectiveness), overall work productivity loss (absenteeism + presenteeism), and activity impairment scores was assessed relative to 5 measures of disease severity and health status: CD Activity Index (CDAI), Short Form-36 physical component summary (PCS) and mental health component summary (MCS) scores, Inflammatory Bowel Disease Questionnaire (IBDQ), and the 5-dimensional EuroQoL health-related quality-of-life visual analog scale (EQ-VAS). Responsiveness was assessed by comparing changes in WPAI:CD scores from baseline to week 26 for patients in remission (CDAI <150 points) versus no remission. Standardized Response Means (SRMs) were calculated to evaluate the magnitude of the changes.

A total of 662 patients (mean [range] age, 37.4 [18-77] years; male, 288 [43.5%]; white, 629 [95.0%]) were enrolled in the study. Patients with CD of the worst severity (CDAI > median) showed significantly higher impairment in work (+10.5%) and activities (+10.4%) versus patients with "best health" (no problems) (both, P < or = 0.001). Patients with "worst" IBDQ, PCS, MCS, and EQ-VAS scores also showed significantly higher impairments in work (IBDQ, VAS -24.2%; PCS, -24.1%; MCS, -15.9%; EQ-VAS, -16.5%) and activities (IBDQ, -23.3%; PCS, -21.8%; MCS, -16.5%; EQ-VAS, -17.2%) versus "best" scores (all, P < 0.05). There were significant differences between WPAI:CD impairment scores for patients in remission versus patients failing to achieve remission (P < 0.05). SRMs were small (ie, <0.5) in the nonre-mission group, and moderate to large (ie, >0.5) for patients in remission.

The discriminative validity, reliability, and responsiveness of the WPAI:CD were demonstrated. The WPAI:CD may be useful for evaluating drug impact on CD.