Faecal calprotectin, lactoferrin, M2-pyruvate kinase and S100A12 in severe ulcerative colitis: a prospective multicentre comparison of predicting outcomes and monitoring response

OBJECTIVE

To compare four faecal markers for their ability to predict steroid refractoriness in severe paediatric ulcerative colitis (UC). Construct validity and responsiveness to change were also assessed.

METHODS

This was a prospective multicentre cohort study. Stool samples from 101 children (13.3 + or - 3.6 years; Pediatric UC Activity Index (PUCAI) at admission 72 + or - 12 points) were obtained at the third day of intravenous steroid therapy. Repeated samples at discharge were obtained from 24 children. Predictive validity was assessed using diagnostic utility statistics to predict steroid failure (ie, the need for salvage treatment). Concurrent validity was assessed using correlational analysis with the following constructs: PUCAI, Lindgren and Seo scores, physician's global assessment, albumin, erythrocyte sedimentation rate and C-reactive protein (CRP). Responsiveness was assessed using test utility and correlational strategies.

RESULTS

Median values (IQR) were very high at baseline for all four markers (calprotectin 4215 microg/g (2297-8808); lactoferrin 212 microg/g (114-328); M2-pyruvate kinase (M2-PK) 363 U/g (119-3104); and S100A12 469 microg/g (193-1112)). M2-PK was numerically superior to the other three markers and CRP in predicting response to corticosteroid treatment (area under the receiver operating characteristic (ROC) curve 0.75 (95% CI 0.64 to 0.85; p<0.001) vs <0.65 for the others). However, it did not add to the predictive ability of the PUCAI (area under the ROC 0.81 (95% CI 0.73 to 0.89)). M2-PK also had the highest construct validity but with a modest mean correlation with all constructs (r=0.3; p<0.05). None of the markers was responsive to change (Spearman's rho correlation with change in the PUCAI <0.1; p>0.05, area under the ROC curve <0.65; p>0.05).

CONCLUSIONS

The four markers were greatly elevated in severe paediatric UC. Only M2-PK had good construct and predictive validity, and none was responsive to change. The PUCAI, a simple clinical index, performed better than the faecal markers in predicting outcome following a course of intravenous corticosteroids in severe UC.

Severe pediatric ulcerative colitis: a prospective multicenter study of outcomes and predictors of response

BACKGROUND & AIMS

In a prospective study of children with severe ulcerative colitis (UC), we aimed to assess outcomes and to identify predictors of nonresponse to intravenous corticosteroids.

METHODS

A total of 128 children (47% males; 12.9 +/- 3.9 y) hospitalized for severe UC were enrolled from 10 pediatric centers. Clinical and laboratory data and the Pediatric UC Activity Index (PUCAI) were recorded throughout the admission. Patients were followed up for 1 year postdischarge.

RESULTS

Thirty-seven (29%; 95% confidence interval [CI], 22%-37%) children failed intravenous corticosteroids and received, within 10.5 +/- 6.4 days, cyclosporine (n = 1; 3%), colectomy (n = 3; 8%), or infliximab (n = 33; 89%). Several predictors were associated with intravenous corticosteroids failure, but the best model included number of stools, amount of blood, age, and new-onset disease (odds ratio [OR], 1.9; 95% CI, 1.1-3.5; OR, 2.5; 95% CI, 1.3-4.6; OR, 1.2; 95% CI, 1.04-1.36; and OR, 0.27; 95% CI, 0.1-0.7, respectively). The PUCAI, followed closely by the Travis rule, strongly predicted response when compared with other measures (Seo and Lindgren indices, C-reactive protein level, and fecal calprotectin level) (P < .001). Aiming for sensitivity on day 3, a PUCAI greater than 45 screened for patients likely to fail intravenous corticosteroids (negative predictive value, 94%; positive predictive value, 43%; P < .001). Aiming for specificity on day 5, a PUCAI score greater than 70 optimally guided implementation of salvage therapy (positive predictive value, 100%; negative predictive value, 79%; P < .001). Twenty-five of 33 children treated with infliximab responded. The overall cumulative colectomy rate was 9% and 19% by discharge and 1-year, respectively. The day 3 PUCAI score predicted response up to 1 year postdischarge (P < .001; time to salvage therapy).

CONCLUSIONS

The PUCAI, calculated on days 3 and 5 of steroid therapy, can identify patients requiring salvage therapy. Infliximab is an effective therapy in steroid-refractory pediatric UC.

Development, validation, and evaluation of a pediatric ulcerative colitis activity index: a prospective multicenter study

BACKGROUND AND AIMS

Colonoscopic appearance, the primary measure of disease activity in adult ulcerative colitis, is less acceptable to children. Our aim was to develop a noninvasive activity index of pediatric ulcerative colitis.

METHODS

Item selection was performed judgmentally using a Delphi group of 36 experts in pediatric inflammatory bowel disease. Item weighting was performed by regression modeling using a prospective cohort of 157 pediatric ulcerative colitis patients. Validation was assessed on a separate prospective cohort of 48 children with ulcerative colitis undergoing complete colonoscopy. Responsiveness was evaluated at a follow-up visit of 75 children using effect size statistics and diagnostic utility approaches.

RESULTS

A list of 41 items was generated and reduced to 11 by rank order. Two physicians completed the Pediatric Ulcerative Colitis Activity Index (PUCAI) on each of the patients in the weighting cohort. Six clinical items were significant in the regression analysis; the laboratory items and an endoscopic appearance item did not improve the PUCAI performance. In the validation cohort, the PUCAI was highly correlated with the Physician's Global Assessment (r = 0.91, P < .001), Mayo score (r = 0.95, P < .001), and colonoscopic appearance (r = 0.77, P < .001). Correlations were higher than 2 noninvasive adult indices calculated concurrently. Interobserver and test-retest reliability were excellent (intraclass correlation coefficient = 0.95; 95% CI: 0.93-0.97). Cut-off points were established using receiver operator characteristic curves on the full cohort. Excellent responsiveness was found at repeated visits (effect size = 1.9, area under the receiver operator characteristic curve = 0.97).

CONCLUSIONS

The rigorously developed PUCAI is a noninvasive, valid, highly reliable, and responsive index with which to assess disease activity in pediatric ulcerative colitis.