Background: We evaluated the psychometric performance of the Pediatric Ulcerative Colitis Activity Index (PUCAI) in a real-life cohort from the Pediatric IBD Collaborative Research Group.
Methods: Two consecutive visits of 215 children with ulcerative colitis (UC) were included (mean age 11.2 +/- 3.6 years; 112 (52%) males; 63 (29%) newly diagnosed and the others after disease duration of 24 +/- 15.6 months). Validity was assessed using several constructs of disease activity. Distributional and anchor-based strategies were used to assess the responsiveness of the PUCAI to change over time following treatment.
Results: Reflecting feasibility, 97.6% of 770 eligible registry visits had a completed PUCAI score versus only 47.6% for a contemporaneously collected Pediatric Crohn's Disease Activity Index (odds ratio = 45.8, 95% confidence interval [CI] 28.6-73.5) obtained for children with Crohn's disease accessioned into the same database. The PUCAI score was significantly higher in patients requiring escalation of medical therapy (45 points [interquartile range, IQR, 30-60]) versus those who did not, (0 points [IQR 0-10]; P < 0.001), and was highly correlated with physician's global assessment of disease activity (r = 0.9, P < 0.001). The best cutoff to differentiate remission from active disease was 10 points (area under receiver operating characteristic curve [AUC] 0.94; 95% CI 0.90-0.97). Test-retest reliability was excellent (intraclass correlation coefficient = 0.89; 95% CI 0.84-0.92, P < 0.001) as well as responsiveness to change (AUC 0.96 [0.92-0.99]; standardized response mean 2.66).
Conclusion: This study on real-life, prospectively obtained data confirms that the PUCAI is highly feasible by virtue of the noninvasiveness, valid, and responsive index. The PUCAI can be used as a primary outcome measure to reflect disease activity in pediatric UC.