Introduction: There is increasing interest in measuring mucosal inflammation in Crohn disease (CD), but there are minimal data correlating the Pediatric Crohn's Disease Activity Index (PCDAI) versions (PCDAI, weighted Pediatric Crohn's Disease Activity Index [wPCDAI], abbreviated Pediatric Crohn's Disease Activity Index [abbrPCDAI], and the short Pediatric Crohn's Disease Activity Index [shPCDAI]) with mucosal inflammation.
Methods: We aimed to compare the 4 PCDAI versions head to head with endoscopic degree of inflammation as measured by the Simple Endoscopic Score for Crohn's Disease (SES-CD), fecal calprotectin, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) and to explore cut-off values that are associated with mucosal healing. We used the prospectively collected data from the ImageKids study on 100 children with CD undergoing colonoscopy and from the Growth Relapse and Outcomes with Therapy study (n = 222), in which 145 children had calprotectin data at week 12 after diagnosis.
Results: All 4 PCDAI versions had fair correlation with the SES-CD (r = 0.42-0.45, all P < 0.001) and CRP (r = 0.32-0.45, all P < 0.01); the wPCDAI and PCDAI were superior to the shorter versions when comparing the blood tests. All versions had poor correlation with calprotectin, and only the wPCDAI reached significance (r = 0.26, P = 0.002 vs r = 0.15, P = 0.07 for PCDAI; r = 0.08, P = 0.37 for shPCDAI; r = 0.06, P = 0.5 for abbrPCDAI). The best cut-off to identify endoscopic mucosal healing was <12.5 points for the wPCDAI (sensitivity 58% and specificity 84%) and <10 for PCDAI (sensitivity 63% and specificity 77%).
Conclusions: The more feasible wPCDAI and the PCDAI had comparable correlation with measures of endoscopic inflammation. These were slightly superior to the other 2 shorter versions, but still none of the PCDAI versions can give a valid assessment of mucosal healing.