Analysis of Using the Total White Blood Cell Count to Define Severe New Onset Ulcerative Colitis in Children.

OBJECTIVES To assess common laboratory tests in identifying severe ulcerative colitis in children at diagnosis. METHODS A cohort of 427 children 4-17 years of age newly diagnosed with ulcerative colitis (UC) was prospectively enrolled. Boosted classification trees were used to characterize predictive ability of disease attributes based on: clinical disease severity using Pediatric Ulcerative Colitis Activity Index (PUCAI), severe (65+) vs. not severe (< 65) and total Mayo score, severe (10-12) vs. not severe (<10); mucosal disease by Mayo endoscopic sub-score, severe (3) vs. not severe (< 3); and extensive disease vs. not extensive (left-sided and procto-sigmoiditis). RESULTS Mean age was 12.7 years; 49.6% (n = 212) were female, and 83% (n = 351) were Caucasian. Severe total Mayo score was present in 28% (n = 120), mean PUCAI score was 49.8 ± 20.1, 33% (n = 142) had severe mucosal disease with extensive involvement in 82% (n = 353). Classification and regression trees identified white blood cell count (WBC), erythrocyte sedimentation rate (ESR), and platelet count (PLT) as the set of three best blood laboratory tests to predict disease extent and severity. For mucosal severity, albumin (Alb) replaced PLT. Classification models for PUCAI and Total Mayo provided sensitivity of at least 0.65 using standard clinical cut-points with misclassification rates near 30%. CONCLUSIONS A combination of the WBC, ESR and either PLT or Alb is the best predictive subset of standard laboratory tests to identify severe from non-severe clinical or mucosal disease at diagnosis in relation to objective clinical scores.