OBJECTIVES: The study was designed to identify the final CLIQ – the first patientreported outcome measure specific to adults with Crohn's Disease (CD) and determine its unidimensionality, reproducibility and construct validity. The measure has two scales; Activity limitations and needs-based Quality of Life (QoL).
METHODS: CD patients were sent a package consisting of the CLIQ, the Nottingham Health Profile (NHP), the Unidimensional Fatigue Impact Scale (U-FIS) and a demographic questionnaire. A subset of respondents received a second questionnaire package 2 weeks later. Rasch analysis was applied to responses for item reduction and assessment of unidimensionality. Assessments of internal consistency, test-retest reliability and construct validity were also undertaken.
RESULTS: The CLIQ was completed by 273 CD patients (65.6% female; aged 16-79 years (mean: 43.9; SD 15.1). 101 patients completed and returned the second package. Both scales had good overall fit to Rasch model (Chi2 p = 0.35; Chi2 p = 0.13 for activity limitations and QoL respectively) and unidimensionality of the scales was confirmed. No evidence of DIF by age or gender was found and the scales had good coverage of the measurement constructs. Internal consistency was 0.91 for the QoL scale and 0.93 for Activity limitations. Good reproducibility was observed (QoL 0.91, Activity limitations 0.89) and both scales were able to distinguish between self-perceived disease severity and general health status groups (p less than .01).
CONCLUSIONS: The CLIQ is the first CD-specific PRO and is truly patient-based as its content was generated directly from CD patients. It is well accepted, completed by patients and is easy to score. Both scales measure a clear unidimensional construct and generate valid total scores. The scales have good consistency, reproducibility and promising construct validity. Studies are planned to assess responsiveness. The CLIQ will prove to be an important tool for assessing Activity limitations and QoL in clinical audit, practice and trials.
