Volume 133, Issue 2, Pages 423-432 (August 2007) Development, Validation, and Evaluation of a Pediatric Ulcerative Colitis Activity Index: A Prospective Multicenter Study  Dan Turner, Anthony R. Otley, David Mack, Jeffrey Hyams, J. de Bruijne, Krista Uusoue, Thomas D. Walters, Mary Zachos, Petar Mamula, Dorcas E. Beaton, A. Hillary Steinhart, Anne M. Griffiths  Gastroenterology  Volume 133, Issue 2, Pages 423-432 (August 2007) DOI: 10.1053/j.gastro.2007.05.029 Copyright © 2007 AGA Institute Terms and Conditions

Figure 1 Study design and outline of the PUCAI development. Footnote: Construct validity is a minitheory to explain whether a measure acts the way it is expected based on the concept that it represents. Concurrent validity reflects the relationship of the index to another instrument measuring a similar attribute and convergent validity of the relationship with another established index. Extreme group validity reflects whether the measure differentiates extreme sides of the disease spectrum. Interobserver reliability reflects whether an index is reproducible between different raters at the same time and test-retest reliability whether a score is reproducible at different times, when the patient remains stable. Responsiveness reflects the ability of an instrument to detect accurately the change in disease activity over time, when it occurs. IBD, inflammatory bowel disease; UC, ulcerative colitis. Gastroenterology 2007 133, 423-432DOI: (10.1053/j.gastro.2007.05.029) Copyright © 2007 AGA Institute Terms and Conditions

Figure 2 Cut-off and change scores of the PUCAI. (A) PUCAI score distribution of the combined weighting and validation cohort (n = 205), stratified by the Physician’s Global Assessment of disease activity. The median PUCAI scores were significantly different across the 4 groups (Kruskal–Wallis test = 1783, P < .001). ROC, sensitivity, and specificity were calculated for “none” vs “mild,” “mild” vs “moderate,” and “moderate” vs “severe.” (B) ΔPUCAI (the difference in the score between baseline and follow-up visits) stratified by physician global assessment of change (on a 7-point Likert scale of change). The median ΔPUCAI was significantly different across the 4 groups (Kruskal–Wallis test = 42.63, P < .001). AUC, area under the curve; ROC, receiver operator characteristic. Gastroenterology 2007 133, 423-432DOI: (10.1053/j.gastro.2007.05.029) Copyright © 2007 AGA Institute Terms and Conditions