Purpose Despite the significant impact of Crohn's disease (CD) on patients' physical and emotional well-being, no CD-specific patient-reported outcome (PRO) measure is available for determining the efficacy of interventions. The objective of the study was to develop and validate the Crohn's Life Impact Scale (CLIQ), the first such measure.
Methods Questionnaire content was derived from qualitative interviews with CD patients and face and content validity assessed by cognitive debriefing interviews (CDIs) with patients. A postal survey was conducted to identify the final scale, confirm its unidimensionality and determine reproducibility and construct validity. A subset of the respondents was sent a second questionnaire package 2 weeks after the first. The survey included the CLIQ, Nottingham Health Profile (NHP) and Unidimensional Fatigue Impact Scale (U-FIS).
Results Content analysis was conducted on the 30 interview transcripts and a draft scale produced. The CDIs indicated that the draft scale was relevant, clear and easy to use. The questionnaire package was completed by 273 CD patients (65.6 % male; aged 16-79 (mean 43.9; SD 15.1) years). Of these, 104 also completed the second package. Rasch analysis confirmed a 27-item unidimensional QoL scale (p <0.05). Both internal consistency and test-retest reliability were high (0.91). Scores on the CLIQ were related to both physical and emotional impairments (NHP) and to fatigue (U-FIS).
Conclusion The CLIQ, the first CD-specific PRO, is unidimensional and has excellent psychometric properties. It should prove to be a valuable tool for evaluating the impact of CD and its treatment from the patients' perspective.